User talk:EngineerSteve

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We're so glad you're here! TheThingy ^Talk 00:28, 14 May 2007 (UTC)[reply]

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IvoShandor 11:05, 4 October 2007 (UTC)[reply]

E-book

I'm concerned about your addition of links to your e-book on a number of spline-related articles. I glanced at the book, and while it appears to be a fairly decent treatment of splines, I'm concerned you may be violating Wikipedia's rules about citing yourself. Namely, you've just been adding your book as en external link, without adding other content to the article or using it as a citation for an uncited statement. If you believe your e-book should be an external link or a reference, could you maybe explain (in each article's talk page) why the link belongs in that specific article? Without distinct rationale for each page, it could easily be construed as spam. Thanks. 107.10.43.91 (talk) 22:22, 28 August 2011 (UTC)[reply]

I too have noticed this and started removing them. Wikipedia's guidelines are clear. You should not link to a site of your own or that you represent, even if it is one that would normally be linked. Even more so as the link was added to multiple articles with a long promotional description making it link spam.--JohnBlackburne^words_deeds 23:05, 28 August 2011 (UTC)[reply]

Thanks. While my book was done with very serious intent and, I believe I gave a very good treatment as I state in it, I have moved on and am unable to add much to any of the Wiki pages considering other contributors are far more advance that I. I only want those who wish to understand more without the typical rigor found elsewhere the opportunity to benefit from my work which goes 'up to' the point of many of these articles. Sorry John, not trying to make work for you. If there is a better way to so this I'll follow recommendations. I'd appreciate it by CONTACT via my site http://home.comcast.net/~k9dci/site/ John, The "...long promotional description ..." was in response to the request for "distinct rationale " from user 107.10.43.91 -- Steve -- (talk) 23:16, 28 August 2011 (UTC)[reply]

Yep, the "promotional description" may have been my fault - I did, after all, request it. I appreciate that you did add rationale, but I was hoping for individual explanations for each article, specifically stating why, for that article, your work should be linked. Something along the lines of an explanation of what the already-cited works missed that your book captured. In any case, I'm still leery about the self-citation, especially if it's just an external link. 107.10.43.91 (talk) 23:30, 28 August 2011 (UTC)[reply]

OK, but Arrrg. I figured I made it applicable with the parts about "... for those new to the subject and aimed at graphics." and "...fundamentals for beginners as well as an extensive reference for many commonly used curve types". Reading all the cited references is much for me now. If you read the WHY on my site, you'll understand that for someone coming in from another area has quite a bit of difficulty getting up to speed in this subject.

Oh well... I'll just keep putting ocassional posts referencing it on NetNews comp.graphics.algorithms and some can benefit, but that's so...well ... old school, not to mention full of garbage. (;-) . -- Steve -- (talk) 23:43, 28 August 2011 (UTC)[reply]

The promotional description was e.g. in this change: "A Study of Piecewise Polynomial Interpolation fundamentals for beginners as well as an extensive reference for many commonly used curve types.". You need only compare it to the other links on that page to see the problem with it. As for a better way the best way is to improve the articles directly. It is often harder and more work to improve an existing article within the constraints of Wikipedia, but the end result is much more beneficial.--JohnBlackburne^words_deeds 23:52, 28 August 2011 (UTC)[reply]

OK, I understand what you're after. I have contributed before, but just thought it would be a nice addition. Regards, Steve -- Steve -- (talk) 01:51, 29 August 2011 (UTC)[reply]

thank you.

Dear EngineerSteve,

Thank you for putting online a rough draft of your book "Interpolation and Curves for Graphics".

I found it more useful than most of the stuff on spline curves I've seen online. (I'm looking for information on splines because currently, all RepRaps always move in straight lines. Printing a part with smooth curves requires sending thousands of tiny little short straight lines through the serial port. Sometimes "little blobs" show up on printed parts. There is speculation that those blobs happen when the Arduino or maybe the USB driver can't keep up with that firehose of little short lines, and the print head keeps oozing plastic while it's waiting for the next command. I'm thinking about tweaking the software to send a handful of longer spline curves instead. I don't know yet if that will make any observable difference).

I agree that too many of Wikipedia articles seem to be written in ways that are difficult for beginners to understand. And it seems to be taking a long time for people to understand that WP:TECHNICAL requires that articles be accessible to beginners as well as experts.

I felt the same way about data compression algorithms, so I'm writing the book on data compression that I've given up on hoping that someone else would write, at Wikibooks: Data Compression.

Have you considered posting a rough draft of your book at Wikibooks? There's already a few brief mentions of splines there, such as Wikibooks: Floating Point/Fixed-Point Numbers#sine table.

I think the easiest way to get started at Wikibooks is to post somewhere on your web site, perhaps on page http://home.comcast.net/~k9dci/site/?/page/Piecewise_Polynomial_Interpolation/ , something like the license at the bottom of every http://xkcd.com/ comic, something like "This draft of the book "Interpolation and Curves for Graphics" is licensed under a Creative Commons Attribution-ShareAlike License. Feel free to post it on Wikibooks."

How can I help? --DavidCary (talk) 21:26, 12 February 2013 (UTC)[reply]

→This is just an email test...Me 71.201.108.65 (talk) 17:26, 21 February 2013 (UTC)[reply]

→ Repeat with email turned on... This is just an email test...Me -- Steve -- (talk) 17:40, 21 February 2013 (UTC)[reply]

Perfect fifth

Hi there,

I've joined in a discussion that was started by you, as I'm interested in improving the lead section of the Perfect Fifth article. If you're able to help out, Here's a link to the relevant discussion:

Talk:Perfect_fifth#Clarification

InternetMeme (talk) 16:20, 23 March 2014 (UTC)[reply]

April 2019

Hello, and thank you for your contributions to Wikipedia. I noticed that you recently added commentary to an article, Garden-path sentence. While Wikipedia welcomes editors' opinions on an article and how it could be changed, these comments are more appropriate for the article's accompanying talk page. If you post your comments there, other editors working on the same article will notice and respond to them, and your comments will not disrupt the flow of the article. However, keep in mind that even on the talk page of an article, you should limit your discussion to improving the article. Article talk pages are not the place to discuss opinions of the subject of articles, nor are such pages a forum. Thank you. Nardog (talk) 18:22, 10 April 2019 (UTC)[reply]

I know that. I mistakenly thought I WAS on the Talk page and rectified the error. I also saw no 4-tilde button there, but it is here. I don't post often enough to remember just how many... -- Steve -- (talk) 19:54, 10 April 2019 (UTC)[reply]

All caps

Steve, writing in all caps is interpreted as shouting here (and generally on the internet) and is considered rude. SpinningSpark 16:02, 18 June 2019 (UTC)[reply]

I'm well aware, Spinning, but don't see where I wrote in _all_ caps? -- Steve -- (talk) 12:38, 19 June 2019 (UTC)[reply]

You all-capped multiple words at Talk:Characteristic impedance/Archive 1#Opening sentence. SpinningSpark 15:43, 19 June 2019 (UTC)[reply]

I frequently like to emphasize a *single* word, similar to when we are speaking. At times I have just first-capped words to Emphasize them. It that more PC? -- Steve -- (talk) 17:30, 19 June 2019 (UTC)[reply]

No answer as of 9 Aug 2020... -- Steve -- (talk) 17:09, 9 August 2020 (UTC)[reply]

Thank you :)

Thank you for trying to talk sense into me some months ago, regarding renaming the dBm article :) · · · Omnissiahs hierophant (talk) 21:20, 26 June 2021 (UTC)[reply]

Bernoulli's principle

Hi Steve, You replied on 21 May (see your diff) but I haven’t been able to respond until now.

The discussion Talk:Bernoulli's principle#My comments on the article structure has drifted away from improvements to the article and turned towards general discussion of the topic of Bernoulli’s principle. Article Talk pages are not appropriate as a forum for general discussion but there is no objection to individual Users conducting a general discussion on their User Talk page. I’m happy to respond to your 21 May discussion here on your Talk page and I encourage you to continue the discussion here.

In your Quora blog titled “Understanding Bernoulli’s principle correctly” you make the following statement It is also for a steady flow that does not change over time. The speed, direction and pressure at any point are constant. We know this sentiment is correct because most good books on fluid dynamics emphasise that Bernoulli’s principle addresses fluid flows in the steady state. None of the variables changes with time. However, in your 21 May edit you have written Changing only ONE THING as follows: Maintaining a constant flow rate in a constant diameter pipe; decrease the cross section of the pipe in one section and the pressure rises upstream - rises. FACT. This statement is not consistent with the agreed position that Bernoulli’s principle addresses the steady state in which nothing changes with time.

Where you say decrease the cross section of the pipe in one section and the pressure rises upstream I assume you are referring to water hammer which is a highly dynamic phenomenon that cannot be modeled accurately using Bernoulli’s principle.

On several occasions in your posts on the Talk page you have drawn readers attention to your blogs on the Quora website and suggested that these are suitable sources for information on Bernoulli’s principle and aerodynamic lift. Your blogs are not satisfactory for at least two reasons. Firstly, Users are discouraged from citing their own publications. There is a conflict of interest. Please read WP:SELFCITE.

Secondly, your blogs are not reliable sources. Most of what I read in your blogs is highly incompatible with what I read in textbooks by respected authors in the field of fluid dynamics. Your blogs mostly constitute what Wikipedia describes as original research. Wikipedia does not publish original research. Please read WP:No original research. For example, you attempt to explain Bernoulli's principle and aerodynamic lift using a very novel application of the word "inertia". I'm sure most of the Users who work on Wikipedia in the field of fluid dynamics will agree with me that trying to explain fluid dynamic phenomena using the concept of inertia is highly unsound. (If any of those Users disagree with me, they are welcome to offer their view here or on my Talk page.)

Information inserted in Wikipedia, especially if it is likely to be challenged, must be attributable to a reliable published source so it can be independently verified. Please read WP:Verifiability. If your views are able to be verified by reference to a reliable published source, those views are welcome on Wikipedia. However, you have not identified any source other than your blogs. Also, your blogs contain a lot of your original research which is incompatible with the views found in works by universally respected authors in the field of fluid dynamics. Dolphin (t) 13:29, 3 June 2025 (UTC)[reply]

Hi, Dolphin,

To start, I could not let that second sentence sit there, since it had been uncorrected for so long.

I wanted to point out the error and tried to provide some correcting information, but others joined in and it took rather long and we got off track.

We were also corrected (I think Swordfish) about discussing subject matter which is why I started the 15 May section “My comments on the article structure”. I tried to make that directly related to the article wording and organization.

. .

We can go to phone or FaceTime to make this easier, but I’ll try here.

.

Re my blog: “Changing only ONE THING as follows: Maintaining a constant flow rate in a constant diameter pipe; decrease the cross section of the pipe in one section and the pressure rises upstream - rises. FACT.”

It is common practice to make sure you make only one change to the given conditions in an experiment and expect that the changes we then observe to be caused by that change, or at the very least, point in the direction of the cause.

That is not hammer – which is more commonly associated with the rapid closing of a valve. I plumbed the house I live in and have the vertical pipes added to prevent it. They, by the way, should be drained periodically because the air can dissolve in the water which allows them to fill over time.

I was, perhaps poorly, trying to show that in the common Venturi setup, it is the harrowing of the pipe that is the cause of an increase in pressure upstream. Then, the following narrow section can be seen as an outlet to that high pressure, thus forming the Pressure Gradient that causes the acceleration into the narrow section.

This pretty much the same effect seen in using a garden hose nozzle on the small stream, or putting a finger over the hose end. The upstream pressure increases because of the restriction in the flow. That increased pressure is precisely why the narrowed stream shoots farther than treh open end of the hose. . .

The important concept is that the restriction is the cause of an upstream pressure rise. This helps to dispel the myth that the “speed causes” the lower pressure - - - And "the faster the flow, the lower the pressure".

Bernoulli is about Acceleration, not speed.

Bernoulli’s Principle is commonly misinterpreted that “speed lowers the pressure of a flow”.

The pressure increase at the restriction ican also be shown at the molecular momentum level with the correct physics, but I won’t go into it here.

.

The following demo demonstrates the concept well – although there is a subtle difference to my described experiment. But it clearly shows the restricted flow to cause a pressure rise and that is the critical concept.

https://www.youtube.com/watch?v=hZ5fZ3K4_mE

.

Then. . .

I provided the links to my blogs to help people on the Talk page better understand what they were obviously having trouble with. From that discussion, I found that others had a better understanding, so, yes, it was directed more to you.

. . At no point did I suggest those be used in the Article.

. . . . . .

If I haven’t mentioned it so far, I have read books and papers by people such as John D. Anderson, Anderson & Eberhart, Doug Mclean, Charles Eastlake - - and discussed these things with some of them, as well as my Aeronautical Engineer son and a couple of others in email and phone.

I also have a discussion planned in a few weeks with Scott Eberhart, when he returns from a trip, regarding a You Tube video I recently ran across.

. . so . . . .

When you see something “which is incompatible with the views found in works by universally respected authors” Let me know with specifics. Perhaps I’ve explained it poorly.

I must note that reading the various authors over the years, I found places where it appeared some were explaining things differently – where they seemed to actually disagree. However, after much careful re-reading, and perhaps some of the follow-up discussions, I found that there were describing the same physics, only using different words. Word/phrase choice can cause troubles – because we have slightly differing definitions for some words – also, context matters.

Having engaged with many people about this, I have refined my explanations based on the way others look at it – along the way I have picked up a few analogies that work well for beginners.

. . . . .

I must be honest that the change you made was so far off base, that I knew you were having trouble with fundamentals and by your comments in Talk, it confirmed that.

I find Wikipedia rather awkward, but Quora easier. Or I’d rather go voice to make it easier to quickly correct misunderstandings, or on Quora.

I’m on Chicago time.

Regards. -- Steve -- (talk) 15:30, 4 June 2025 (UTC)[reply]

YOU indicated we could discuss the physics here, BUT, YOU have jumped back and continues on the Article Talk page and changed the subject. -- Steve -- (talk) 22:35, 5 June 2025 (UTC)[reply]

ON 3 June I wrote: Also, your blogs contain a lot of your original research which is incompatible with the views found in works by universally respected authors in the field of fluid dynamics. You responded on 4 June, saying Let me know with specifics.

It is a major task, but here are some initial comments. I am using the acronym UBPC for your blog "Understanding Bernoulli's Principle Correctly".:

1. PHYSICS by Resnick and Halliday (1960) is an excellent textbook for introduction to the study of physics at the college freshman level. Chapter 18 (“Fluid Dynamics”) of this book introduces the flow of fluids and Bernoulli’s principle. Section 18-3 is an acknowledgement of the primacy of the law of conservation of mass in Newtonian mechanics. It is explained that as fluid moves in streamline flow, mass is conserved. It achieves this using an equation: if at one point in a pipe or stream tube, the cross-sectional area is A₁ and the mean velocity is V₁ then the rate of mass flow at that point is A₁ V₁ ρ where ρ is the fluid density. At any other point, the cross-sectional area is A₂ and the mean velocity is V₂. Continuity of mass stipulates that the rate of mass flow is the same at all points:

A_{1}V_{1}\rho =A_{2}V_{2}\rho

(Resnick & Halliday, Equation 18-1)

Resnick and Halliday explain that where the cross-sectional area of a pipe or stream tube changes, the mean velocity V₂ of an incompressible fluid is completely determined by mass continuity:

V_{2}=V_{1}{\frac {A_{1}}{A_{2}}}

Any other value for V₂ would be inconsistent with mass continuity and so would imply that mass has either been created or destroyed.

Continuity of mass is a more fundamental principle than Bernoulli’s principle. Bernoulli’s principle is not valid in the presence of viscosity or compressibility or the addition/removal of heat. In contrast, continuity of mass remains valid regardless of the presence of any or all of these things, and even if the flow of a gas is supersonic.

In contrast, UBPC does not acknowledge the primacy of the law of conservation of mass in Newtonian mechanics. UBPC states that any increase (or decrease) in the speed of a fluid is caused by, and determined by, the decrease (or increase) in pressure. UBPC says nothing to indicate how the flow regulates its speed in the presence of viscosity or compressibility when Bernoulli’s principle is not applicable.

2. In UBPC, it is explained and then reinforced that the change in speed is caused by the change in pressure but, at least initially, nothing is written about why the pressure changes. At least initially, UBPC says nothing to explain the circumstances that might cause the pressure to increase, or might cause the pressure to decrease.

In the final three paragraphs there is an attempt to explain why the pressure in a pipe or stream tube might change. In the case of a tapering section approaching a venturi UBPC suggests that “inertia” might be responsible for causing an increase in pressure. Resnick and Halliday do not use the word “inertia” or Newton’s First Law of Motion, to explain Bernoulli’s principle.

UBPC also says “fluid trying to flow away from a surface should reduce the pressure.” Instead of an explanation of this statement it simply says “it should be obvious”.

3. The final paragraph of UBPC suggests that “flow along a convex surface lowers the pressure.” An example is given of an airfoil and the text suggests “the higher pressure around the leading edge pushes more rearward, thus speeding it up toward the trailing edge:” It is not generally true to say that flow along a convex surface lowers the pressure. If you know of a reliable or authoritative source that supports your position, please let me know.

Fundamentals of Aerodynamics by John D. Anderson (1984) is an excellent resource for aerodynamicists and aeronautical engineers. At Figure 4.25 (p.222), Anderson shows a plot of pressure distribution around an airfoil generating lift. This plot clearly shows that the point on the airfoil with the lowest pressure (and hence the fastest speed) is on the upper surface and close to the leading edge. Let’s say it is shown approximately 5% of chord aft of the leading edge. The flow adjacent to the upper surface accelerates rapidly to the 5% point and then decelerates progressively all the way to the trailing edge. The upper surface of the airfoil is a convex surface, and over 95% of that surface the flow is slowing down until it reaches the trailing edge. UBPC contradicts Anderson by saying the convex upper surface causes the flow to speed up “toward the trailing edge:”

4. In Section 2.4 (“Continuity Equation”) Anderson introduces the principle of continuity of mass in preparation for presenting Bernoulli’s principle in Section 3.2 (“Bernoulli’s Equation”). In contrast, UBPC does not acknowledge the importance of mass continuity in determining the variation of the speed of a fluid throughout a flow field.

In Section 3.2 (p.118) Anderson writes “Hence, Bernoulli’s equation is also a relation for mechanical energy in an incompressible flow;” In contrast, UBPC does not mention energy. Instead, UBPC talks about “inertia”. Anderson appears not to use the word “inertia”.

5. UBPC uses the expression “True Cause and Effect”. I am unaware of any reliable or authoritative source that acknowledges a principle called “cause and effect”. It may be a principle in philosophy or theology but it has no currency in physics. If you know of a reliable or authoritative source that applies “cause and effect” to Bernoulli’s principle (or any topic in physics) please let me know. Dolphin (t) 12:43, 7 June 2025 (UTC)[reply]

Hi Dolphin.

I carefully read your last, but remember that I initially checked back on Wikipedia and saw that second sentence had been destroyed and had to get it corrected; then got caught up in the discussions.

I have been referring students there for years and expected it to stay correct.

I came here, to MY Talk, to discuss the physics, not article suggestions, or citations. I gave my recommendations for the article back on Talk.

I’m here to discuss the physics with you.

. .

I see that you focus on conservation of mass. You over-explain what I already know about conservation of mass, pipe cross sections, velocity, etc.

Lately, I have focused more on my Lift blog and wanted to review UBPC, so now I will do that with your comments in mind.

. . . .

I don’t start UBPC explaining conservation of mass because it isn’t necessary. I have never run into anyone talking about Bernoulli’s Principle who thought that fluid spontaneously appears or disappears. I would call it naturally ‘intuitive’ that you wind up with what you started with, when it comes to this subject. But, yes, if a cross section of a fluid volume changes, the length must change to retain the volume, but that is not a physics description of why this happens in a flow.

My main purpose in UBPC is to explain the main points that correct the common myth that faster fluid causes a lower pressure – that is, to explain what it takes to understand the correct physics. It is not a graduate course in fluid dynamics.

Nor is it to discuss where Bernoulli’s Principle is not applicable.

The main purpose is showing that speed does not cause a pressure decrease as the common misconception says and the explain the correct cause.

The common misconception is a very clear statement about cause and effect, BUT is false, therefore, it needs to be corrected.

More on cause & effect’ below.

. .

The purpose is showing the physics that the lower pressure is part of a Pressure Gradient that causes Fluid Acceleration, not the result, or ‘effect’.

Then, UBPC covers why the common demonstrations are misinterpreted.

. . .

What is important is that we see some mass accelerating and should understand the force that causes it. Fluids have mass and follow Newton’s laws, therefore, we should be able to show how they do, and that is my purpose.

.

Although you mention Newtonian mechanics, it doesn’t appear you are able to generalize those laws to fluids. That is what I have done and I did see in the Wiki Article that it stated that a Pressure Gradient is the cause of the Acceleration, so the Article does recognize that already.

You have provided no evidence attempting to refute that Inertia is significant. I believe my Lift Blog covers it well and will re- evaluate UBPC.

.

2 – I don’t go into all the reasons a pressure Gradient can form. There can be many. Also, Bernoulli’s Principle gives no hint about what the cause is. That appears to be the source of the common misconception. It is left open for people to assume the cause and they get it wrong. So, cause and effect is at the heart of all this. More on cause below.

.

3 – I have no doubts about the role of Inertia in the explanation in my video for pressure reduction along the convex surface of a wing. Inertia is a fundamental property pf mass and Newton’s First Law is called The Law of Inertia.

When there is flow relative to a surface, Inertia plays an important role because the fluid’s Inertia has a new constraint imposed upon it that must be understood. When the surface and the fluid’s inertia have different directions, the fluid’s inertia resists the constraint of the surface, thus causing a pressure change that causes the flow to follow the surface. A flow does not follow an angled surface for no reason. Inertia “tries” to keep the flow straight and resists, thus changing the pressure.

.

Also -

While there is a notable difference between the wing’s upper flow and the Coanda Effect (it is entrainment), the primary cause of the pressure decrease is also the same inertia for Coanda and he recognized the pressure decrease in one of his patents that I read.

.

If you need an authoritative source describing every instance of some science principle, then so be it, but I can generalize fundamental concepts and apply them to other situations where they apply.

. . .

I think part of the problem with people not fully understanding Newton’s Laws is that we have retained Newton’s wording to honor him, but they are a worded bit vague. We could use the word Inertia in the first law to describe the property that has an object stay stationary, or move at constant velocity and resist a force.

I have also seen others confused with Newton’s third Law, thinking that being “equal and opposite” they should, therefore, cancel – not realizing that the ‘action’ and ‘reaction’ are on different objects.

. . .

Notes:

Resnick and Halliday is a physics book, not fluid dynamics, so I will consider it a secondary source, but Bernoulli’s Equation is Bernoulli’s equation and one can use it.. In the 6^th edition I have, Equation 18-1 is about waves. But that doesn’t matter because I understand how flow works in a pipe or stream tube.

If I haven’t already mentioned; I’ve read books and papers by John D. Anderson, David Anderson & Scott Eberhart, Doug McLean and Charles Eastlake as well as discussed this with some of those authors and a few other processionals in fluid dynamics, as well as my Aeronautical Engineer son. This is to show that I don’t just quote other authors, but use reason to understand the principles and apply them correctly.

.

5 – Cause & Effect in science. Other than the fact that this is the primary and most important, fundamental purpose of science, I can’t provide a ‘reference’ for this. I am surprised you ask that.

Any scientist worth their salt should know. Below is one reference for “Bernoulli’s Principle”.

John D. Anderson has a history note that Euler is credited, while following up on Bernoulli’s studies, with discovering that a Pressure Gradient is the cause of fluid Acceleration. It is simply Newton for the mass in a fluid.

The concept of pressure providing the force to accelerate a mass is a clear physics explanation whereas only stating conservation of mass is a general concept that does not explain the cause of the fluid’s acceleration. It is deductive reasoning, rather than giving a clear cause for the fluid’s acceleration. It only says that it must occupy a longer distance in the narrow section to maintain the same volume, but nothing about a force to accelerate the mass. We are operating under Newtonian mechanics where acceleration has a cause.

. .

I, and others, know that you do not truly understand physics until you understand the cause and effect for phenomena. That is the end goal of millions of scientists. Figuring our WHY things happen.

If THAT concept isn’t obvious to you, it tells me it is part of the reason you are having trouble with this. It can be considered to be the fundamental purpose of science.

There are cases in science where we may only understand that some things “do happen” and know something about the conditions under which they occur without knowing why, but still use that to our advantage, BUT the ultimate goal is to fully understand what causes what. THEN you can typically do so much more with those fundamental concepts / principles.

Before germs and viruses were discovered, people thought gasses, or auras caused illnesses. Now we have vaccines that came from careful study of the cause of disease and how the body fights germs. BTW, I was in the 1954 Salk Polio Vaccine Clinical Trial in 3^rd Grade. Because viruses were discovered, along with the how and WHY the body did, or didn’t fight them off, scientists now *KNOW* that we can make vaccines to eliminate some diseases;

. . . WHY = Cause and effect.

. . . . . . .

Collins dictionary clearly says Pressures cause Acceleration:

“physics

the principle that in a liquid flowing through a pipe the pressure difference that accelerates the flow when the bore changes is . . . .”

https://www.collinsdictionary.com/us/dictionary/english/bernoullis-principle

. . . .

I don’t think I can explain any better.

I will be reviewing UBPC and update it as appropriate to better explain areas you mention.

Regards, Steve -- Steve -- (talk) 21:44, 10 June 2025 (UTC)[reply]

P.S. Reviewing UBPC, I see shortcomings and will work on it for the next few days / weeks. -- Steve -- (talk) 01:52, 12 June 2025 (UTC)[reply]

I noticed the changes to UBPC. Well done! I think they make useful additions and improve the information provided to readers. I will read more closely in coming days. Dolphin (t) 13:06, 15 June 2025 (UTC)[reply]

I will be doing more. Busy weeks. -- Steve -- (talk) 15:11, 15 June 2025 (UTC)[reply]

In UBPC you say: “The following video explains how flow along a convex surface lowers the pressure as the inertia ‘wants’ to continue straight in an upward direction, thus resisting the atmospheric pressure forcing it to follow the curved path. The inertia here opposes the inward acceleration, thus reducing the pressure near the surface. This is valid for flow along ANY convex surface.”

A very similar presentation, but perhaps with one significant difference, has been provided by Professor Holger Babinsky of the University of Cambridge. In the November 2003 edition of Physics Education he published an excellent paper titled “How Wings Work”.

See "Physics Education" pp.497-503

On page 500 is a section titled “Flow along curved streamlines”. It contains the following explanations:

“In other words, if a streamline is curved, there must be a pressure gradient across the streamline, with the pressure increasing in the direction away from the centre of curvature.”

“This explains why there are such low pressures in the centre of vortices (and why tornados ‘suck’ objects into the sky).”

The difference between your statements and those of Babinsky is that yours may be referring to reducing pressure all the way along any convex surface - a pressure gradient in the streamwise direction. In contrast, Babinsky (and other authors) are describing a pressure gradient perpendicular to curved streamlines such that the lowest pressure lies in the direction of the center of curvature.

If it is your intention to refer to exactly the same pressure gradient as Babinsky, I suggest you adjust your statements so you use similar words. That will show you and he are in agreement.

Babinsky also provides an excellent analysis of the relevant physics in an Appendix on p.503 Dolphin (t) 13:06, 16 June 2025 (UTC)[reply]

Hi Steve,

On 4 June you wrote The important concept is that the restriction is the cause of an upstream pressure rise. You invited me to view the YouTube video. It appears to have been made by a person named Enbin Zheng. I have watched it several times. As a demonstration of the phenomenon it is interesting but I found it disappointing that the only attempt to explain why the restriction increases the upstream pressure is to present the “resistance formula of pipeline”:

h_{f}=\lambda {\frac {L}{D}}{\frac {V^{2}}{2g}}

This equation is immediately recognisable as the Darcy-Weisbach equation in which:

h_f is the loss of hydraulic head over a length L of a circular pipe

λ is the flow coefficient

D is the diameter of the circular pipe

V² is the square of the average velocity of the flow through the pipe

g is the acceleration due to gravity

The Darcy-Weisbach equation describes the progressive loss of hydraulic head along the length of a pipe carrying a flow of water. This progressive loss of hydraulic head is due to fluid friction and is caused by the viscous shear stress between the water and the inner wall of the pipe. It was introduced 180 years and is still in widespread use today. It is sufficiently important that Wikipedia has an article devoted to it. See Darcy-Weisbach equation.

The significance of Enbin Zheng showing this equation in his video is that he is acknowledging that the flow of water through the pipe in his demonstration experiences fluid friction causing a progressive loss of hydraulic head along the pipe. The equation shows that the loss of hydraulic head is proportional to the square of the average velocity. (If the velocity is doubled, the loss of hydraulic head increases four-fold. If the presence of a restriction near the end of the pipe halves the velocity throughout the pipe, the loss of hydraulic head decreases to one quarter of its former value.)

Unfortunately, Enbin Zheng does nothing to explain the meaning of the Darcy-Weisbach, or even the meaning of individual terms. This has attracted adverse comment from at least one person who commented on YouTube. Observ45er wrote “However, I suggest that it is not a good technique to use a formula to explain the science/physics.”

Observ45er summarised the situation perfectly where he or she wrote “Reduced flow causes less pressure loss in the tube from the viscosity along the length of the tube.”

The concepts of a no-slip condition, viscosity, boundary layer, pipe flow, and the Darcy -Weisbach equation explain perfectly why a restriction that reduces the average flow velocity causes a progressive increase in the pressure upstream of the restriction. For an audience that may not be familiar with these terms it would be sufficient to talk about “fluid friction” opposing the flow of water and causing a progressive loss of pressure upstream from the restriction. The slower the average velocity of the water, the closer the pressure is to the pressure in the reservoir at the point where the pipe leaves the reservoir. The faster the average velocity of the water, the more pressure is lost as the water makes its way to the end of the pipe.

This phenomenon is entirely due to viscosity so it is not consistent with Torricelli’s law or Bernoulli’s principle because both of these are explicitly stated to apply only in situations where viscosity is zero or viscous forces are so small that they can be ignored. This phenomenon cannot be used to disprove Torricelli or Bernoulli, and cannot be explained using either of these laws. For example, pressure falls progressively along the pipe but there is no matching increase in average flow speed. We know there can be no change in the average flow speed because the mass of water in the pipe is always conserved. Dolphin (t) 13:15, 23 June 2025 (UTC)[reply]

It appears you memorized things like equations, but not an understanding of the physics behavior they were derived to mimic.

Again and one last time, equations do not explain WHY things happen.

.

You're making it much too complex.

.

As a fluid approaches the inward sloping wall of the tube, the mass / inertia 'wants' to continue straight, but the pipe wall is in the way, so the fluid pushes more on the inner wall. It is just like a wind pushing on you.

INERTIA of the Fluid's Mass.

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If you study fluids you would know that fluid's static pressure acts in all directions, therefore, the pressure in the LARGER diameter section increases.

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That pressure can then accelerate the fluid into the narrower section - it's analogous to an opening in a pressurized tank.

Yes, Enbin has a common viscosity induced head-pressure loss along the small tube as easily seen in that demo.

But there is no reason that that fundamental concept should change with different flow rates. This happens regardless of whether or not the flow slows when the diameter decreases.

.

The inward motion of the fluid in the narrowing area is an acceleration and the mass of the fluid resists (because of inertia) that acceleration (Newton's 3RD Law), thus increasing the pressure in the wide section. This behavior is compatible with Newton's Laws.

IF we force a constant flow rate (unlike Enbin's demo) the FUNDAMENTAL PHYSCS is the same and upstream pressure still increases. This is easily seen with a manometer and keeping a constant flow rate with such a pump.

.

This is a demonstration where you only allow one change. The pipe diameter.

Flow rate is forced to be constant and when the pipe's cross-section is decreased, that upstream pressure increases -- - and Inertia explains it - Newton's First & Third Laws.

The upstream pressure increases because Inertia is a real, fundamental property of mass.

.'

Done.

.

No equations, only plain, well-understood physics expressed in words.

That is understanding - not quoting equations.

.

- - Regards -- Steve -- (talk) 19:16, 23 June 2025 (UTC)[reply]

Hi Steve,

Thanks for your prompt reply.

On the question of why a garden hose will squirt further when a finger is placed over the end of the hose, you replied on Quora saying If the hose and other piping has significant resistance to flow due to viscosity, the reduced flow with the thumb reduces the flow and the pressure loss, therefore the pressure will increases. Yes! You are 100% correct with that explanation. (Of course, a fluid flowing through a pipe always develops shear forces that retard the flow below the speed predicted by Torricelli's law, and cause a progressive reduction in pressure.) The beneficial effect of holding a thumb or finger over the end of a garden hose is a phenomenon of viscosity and viscous shear forces. This was explained by Enbin Zheng.

In your message above you have written The upstream pressure increases because inertia is a real, fundamental property of mass. Have you now changed your mind? You had it right when you identified viscosity as being highly significant but now you have reverted to inertia as the explanation. That is disappointing - you once had it right but now you have it wrong.

Unfortunately this seems to be typical of your thinking and your writing. On Monday you write one thing, only to contradict it by Friday. Wikipedia places great importance on all its published information being verifiable in a reliable published source. Your views and ideas appear to be largely your own creations, with no attempt to link to any reliable source other than claiming you have had discussions with leading experts.

The internet is not censored or regulated so you are allowed to publish any of your ideas on any subject, including fluid dynamics. What I object to is that you claim to have studied aerodynamics when it is clear that you haven't done so; and you claim to have consulted with leading experts when it is clear that your writing shows no sign of any involvement by anyone who might be able to help you as an expert. Most of your readers will be deceived. Honesty is the best policy. Dolphin (t) 13:04, 24 June 2025 (UTC)[reply]

Regarding your 22:01, 18 May 2024 change that put me back on Wikipedia:

"Bernoulli's principle states that an increase in the speed of a parcel of fluid occurs simultaneously with a decrease in either the pressure or the height above a datum"

Thinking at any point, that the basic Bernoulli’s Principle says “an increase in the speed of a parcel of (incompressible) fluid occurs with the (decrease in) height . . .

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. . . is absurd and shows you have little understanding of fundamental physics and should not be changing Wikipedia, nor that you have seriously studied fluid dynamics. While I may complement your determination in trying, you are failing.

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When you can understand how a moving fluid and surface interact and more importantly why the changes occur, then you are understanding the physics.

. .

Yes. As I’ve said, the Enbin Zheng video is dominated by the viscosity caused head loss in that small tube. This is identical to the common finger-over-the-garden-hose, or the change in the nozzle configuration to the narrow jet situations. Garden hoses and the complete water pipe system has that major factor.

. .

However, you missed the essence of my other explanation where a CONSTANT / FIXED flow rate in a pipe shows an upstream pressure increase when a section of pipe is then *modified* by having a part of the cross section reduced (KEEPING the SAME flow rate) – allowing no other changes, especially flow rate.

You jump around, changing the subject with no indication you understand this set of constraints, nor the role the fluid’s Inertia plays.

The lack of understanding of what inertia’s role is along with the constraint of a surface, unfortunately, is common and completely ignored by all the discussions I have seen so far in this type on the web. It is also the fuel for misunderstanding aerodynamic lift of a wing.

. . . . .

Although it could be organized better, the Wiki article does hit the high points about the relation between Pressure and Acceleration. That is is a Pressure Gradient that is the cause of fluid Acceleration.

You failed to understand that understanding cause and effect is the fundamental purpose of the study of science.

. . .

I have been able to start editing my UBPC to remove opportunity for misunderstandings, and will continue as time permits.

. . . . . . . . . . . . .

When you even have PhDs believing and teaching that the ‘fast’ fluid out the end of a hose causers the jet’s pressure to be below atmospheric pressure, it is no wonder so many people don’t understand so much of this. Ref Weber State University Ron Galli, among others.

WSU Weber State University Ron Galli:

Faucet and hose NOT “Bernoulli”. It is Entrainment:

www.youtube.com/watch?v=AnDvjjPQCuE

He also has Bad Bernoulli Demos.

. .

As I said, my knowledge comes from reading noted texts and discussions with some well-known Aerodynamicists. I had a nice conversation with Scott Eberhardt a few days ago. Coauthor of Understanding Flight. By David F. Anderson, Scott Eberhardt.

Which books have you read and who have you talked to, to learn from?

. . .

Regards. -- Steve -- (talk) 14:04, 4 July 2025 (UTC)[reply]

On 4 July you asked me what books I have read. If you want me to tell you about all the aerodynamics books I have read, you must first tell me about all the aerodynamics books you have read. However, I’m willing to identify one book I have read, and to quote something from that book that is highly relevant to our present discussions, and to provide an explanation. I will appreciate it if you will do the same regarding a relevant book you have read. If you do that I will identify a second book I have read.

In 1978 I bought a copy of “Mechanics of Flight” by A.C. Kermode (eighth edition 1972) published by Pitman Publishing Corporation. It has been my constant companion for the past 46 years and I’m confident I have read every word it contains. It is an easy entry-level book for any reader interested in aeronautics and aerospace engineering. It contains a little basic arithmetic and algebra but nothing too challenging.

In Chapter 2 “Air and Airflow – Subsonic Speeds” it contains an excellent section titled “Bernoulli’s Theorem” (on page 60 in my copy.) It says:

… Bernoulli’s Theorem which states that in the streamline flow of an ideal fluid i.e. one which is not viscous – the sum of the energy of position (or potential energy) plus the energy of motion (or kinetic energy) plus the pressure energy will remain constant. In the cases in which we are concerned there is not sufficient change in the height of the fluid to have any appreciable effect on the first term of this sum i.e. on the potential energy, therefore the sum of the last two terms should remain constant, which means that if all the kinetic energy is lost on striking the plate it should be completely converted into pressure energy.

Firstly, Kermode correctly states that Bernoulli’s Theorem says the total energy of the fluid will remain constant, and that the total energy consists of three elements – potential energy, kinetic energy and pressure energy.

Secondly, Kermode correctly states that in the aerodynamics associated with the flight of aircraft, the various changes in the height of the fluid will not have any appreciable effect so the potential energy term may be omitted. Many authors of books on aerodynamics omit the potential energy term but choose not to remind readers that this omission is only reasonable when dealing with situations where there is no significant variation in height. This is a specialist form of Bernoulli’s Theorem and does not represent the Theorem in its general form. Sadly, some readers, and I think you might be one of them, do not realise that omitting the potential energy term can be a serious mistake if they imagine that Bernoulli’s Theorem in its general form does not have a potential energy term.

When I have written about a fluid flow that undergoes a change in height and simultaneously a change in velocity, such as a stream of water poured from a cup, or a waterfall, you have described my comments as “absurd”. It looks like you might imagine the general form of Bernoulli’s Theorem does not contain a potential energy term. Kermode describes it very well.

If you aren’t familiar with “Mechanics of Flight” by Kermode I can recommend it highly. It makes easy reading and is packed with information on the subjects of aerodynamics, aeronautics and aviation.

You also asked me who I have talked to. If you want me to tell you about the people I have talked to, you must first tell me about all the people you have talked to. However, I’m willing to identify one expert I have spoken to on a subject that is highly relevant to our present discussions, and to provide some comment about what we talked about. I will appreciate it if you will do the same regarding an expert you have talked to.

I have had a number of discussions with Dr Graham Wild, college professor in the field of aerodynamics and aerospace engineering. Following are some easily accessible documents written by Graham in one of his fields of interest.

My discussions with Graham revolved around the unsatisfactory situation in which trainee pilots and other interested persons are encouraged to believe that the Coanda effect is a satisfactory explanation of aerodynamic lift. Coanda effect is a name but it doesn’t constitute an explanation of anything, as explained by Doug McLean in his 2012 book “Understanding Aerodynamics – Arguing From The Real Physics”.

What topic have you discussed with an expert in the field of aerodynamics? Dolphin (t) 14:11, 6 July 2025 (UTC)[reply]

FIRST: Read this carefully:

I said that your change in wording of Bernoulli's Principle. stating that velocity varies with height above a datum, was absurd and is clearly out of place in that second sentence referring to the common wording we call "Bernoulli's Principle".

Your wording was NOT Bernoulli's Principle.

-

YOU admitted it was out of place because you were incorrectly thinking of an unrelated concept of static pressure variation with fluid depth - You showed an image of a tank with holes in the side to show your thought process.

That change was completely unwarranted.

.

In addition, your example of free-falling liquid has a completely different set of constraints - most significantly, no tube containing the flow as used by Bernoulli himself.

.

I see that you appear to have difficulty separating different situations that do not share the required conditions and conflate incorrect situations. I have seen the same thing in other sections of the discussion we have had here.

. . . .

Now, in short:

A number of years ago I read all the books about early flight I could find, focusing on books by and about the Wright brothers, Octave Chanute, Glenn Curtiss, including Wolfgang Langewiesche “Stick and Rudder” . . . and the other notable people in flight,

- Kermode 'Mechanics of Flight' is one of those I have and reviewed early-on.

- Another interesting one is George Collinge’s articles on lift showing air motions around a wing.

. .

Authoritative books I studied:

- Both of Aerodynamicist John D. Anderson’s books.

- Doug McLean’s book - and TPT articles.

. .

People I discussed Bernoulli and Lift with:

- Boeing’s Aerodynamicist Doug McLean,

- Embry-Riddle’s Aerodynamicist Charles Eastlake - - regarding his paper,

- University of Mich. Aerodynamics Professor Krzysztof Fidkowski,

- MIT’s Aerodynamicist Mark Drela,

- U of Washington Aerodynamicist Scott Eberhardt,

- Australian Technical editor and educator Peter Eastwell,

- Extended discussions with my aeronautical engineer son,

- Many others along the way on YouTube and other web sites regarding Bernoulli’s Principle and Lift.

Also, I plan to talk with David Anderson, Scott Eberhardt‘s co-author, in the next few weeks due to his video I recently ran across.

.

I also had some discussion with Graham Wild, but as I recall, he preferred to focus on equations and the more sophisticated, graduate level, rather than the physical understanding of lift.

.

My primary focus is the fallacies of Bernoulli’s Principle and Lift, but of course, have picked up a few other things along the way.

.

Along with many of the papers I read and could download, I have 42 pages of references/links for what read on the net, both bad and good- - as well as copies of some of the books and many of the articles.

- - -- Steve -- (talk) 19:53, 12 July 2025 (UTC)[reply]

On 12 July you wrote In addition, your example of free-falling liquid has a completely different set of constraints - most significantly, no tube containing the flow as used by Bernoulli himself. No tube containing the flow? Are you saying that Bernoulli’s principle only applies to fluid flows within a tube? If so, that would come as a surprise to all aerodynamicists because they use Bernoulli’s principle to explain the aerodynamic lift on an airfoil. The air flowing past the upper surface of an airfoil is not flowing in a tube. The same applies to the lower surface – no tube.

On 4 July you asked me Which books have you read and who have you talked to, to learn from? I told you about “Mechanics of Flight” by Alfred Kermode – a wonderful book that I respect 100% and from which I learnt a lot. You have since told me about having read authoritative authors John D. Anderson and Doug McLean. I own books by both these authors and I admire their work greatly.

The question in my mind is “What did EngineerSteve learn from reading Anderson and McLean?” The evidence before me indicates you didn’t learn enough to be convinced of the accuracy and wisdom of what these two men have written. When you chose to write Understanding Bernoulli’s Principle Correctly (UBPC) and Understanding Aerodynamic Lift Correctly (UALC), instead of presenting their explanations of classical aerodynamics in simplified language for a non-technical audience you abandoned their wisdom completely and presented your own theories. In UBPC and UALC you choose to go on and on and on and on about inertia being the key to understanding! Paragraph after paragraph after paragraph about acceleration; air pushing up and air pushing down ad nauseum. This bears no resemblance whatsoever to the brilliant writings of Anderson and McLean. You have abandoned their explanations completely and substituted your own fabrications. We must conclude that you didn’t learn much from reading Anderson and McLean because you prefer your own home-grown attempts at explanation.

At the top of the page of UALC I see the words This uses solid physics and Aerodynamic fundamentals to explain the true how and why a wing creates lift. This is false and deceptive. UALC does not use solid physics - “you can also call inertia momentum”. Newton himself might have used the Latin word inertia but modern authors do not use the word. They certainly don’t explain physical phenomena by saying they are caused by inertia! UALC does not use aerodynamic fundamentals. It uses EngineerSteve’s attempts to explain these things using ideas and phrases he has developed for himself during sessions explaining things to non-scientific audiences of all age groups at the Challenger Learning Center.

If the wisdom of John Anderson and Doug McLean is to be used to explain aerodynamic lift to a non-scientific audience it could be done by explaining that there is a vortex embedded in the flow of air around a wing when it is generating lift. The effect of this vortex is that the air moving over the upper surface of the wing has a higher speed than the air moving past the lower surface. Secondly, the concept of Bernoulli’s principle should be introduced, saying that the faster air passing the upper surface has higher kinetic energy and therefore lower pressure energy than the slower air passing the lower surface. The lower pressure above the wing compared with the higher pressure below the wing leads to an upward force on the wing, and it is caused lift. An explanation of this kind would be compatible with the writings of Anderson, McLean and many others; and would demonstrate that something had been learned from reading their books.

You have mentioned your conversations with various experts including your son. You have carefully avoided saying anything at all about the content of these conversations. I guess you didn’t discuss UBPC or UALC with these people. If you did, I’m sure they didn’t respond positively or with encouragement.

In the Preface to Doug McLean’s book “Understanding Aerodynamics – Arguing …” third paragraph, he writes We’ll encounter several instances … … of erroneous physical explanations that have found their way into our folklore. In any case where a misconception has been widely enough propagated, the “right” explanation would not be complete without the debunking of the “wrong” one. I have tried to do this kind of debunking wherever it seemed appropriate and have not hesitated to say so when I think something is wrong. Doug McLean wouldn’t hesitate to give you a realistic assessment of what he thinks of UBPC and UALC. Dolphin (t) 13:29, 16 July 2025 (UTC)[reply]

Dolphin51.

While I see you’re highly motivated, I could admire that, but. .

Your inability to correctly understand physics fundamentals and apply them correctly, is the reason you made that ‘second sentence’ error and have such difficulty with this.

. . .

I must remind you that the common, simplified version of Bernoulli’s Principle that you can find in many places, states that:

.

“An increase in the speed of a fluid occurs simultaneously with a decrease in static pressure.”

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An increase in the speed is ACCELERATION. . .

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You, however say:

“the concept of Bernoulli’s principle should be introduced, saying that the faster air passing the upper surface has higher kinetic energy and therefore lower pressure energy than the slower air passing the lower surface.”

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That is COMPLETELY and clearly FALSE.

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It is clearly shown to be false in figure 7 in Understanding Lift.

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That diagram of actual wing-flow should have been an epiphany for you to work toward Correctly understanding Bernoulli’s Principle.

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Watching a wing fly by:

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The Fact is: A wing’s lower air reaches a greater peak forward speed than the upper air’s reverse peak speed, because the lower air is continually accelerated forward by the pressure under the forward moving wing.

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The air below the wing has a greater speed magnitude AND a higher pressure than above <-- FACT from measured data.

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To be clear: the Lower air reaches a HIGHER peak forward speed than the upper air’s peak reverse speed.

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However, the upper air is AXCELERATED a GREATER amount (rearward in the same time) by the higher Pressure Gradient above the wing.

In the same time interval, the upper air is first accelerated forward (ahead of the wing), then accelerated rearward so much that is stops and Completely reverses direction – moving in the opposite direction of flight.!.

Backwards.

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The Greater Pressure gradient above a wing ACCELERATES the upper air MORE than the lower air. BUT the upper air winds up at a lower speed BECAUSE of the reversal in direction – during that acceleration.

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That is Proper application of Bernoulli. Acceleration.

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The FACT is that Bernoulli has ABSOLUTELY NOTHING to do with speed along a surface. In fact, nothing to do with speed at all.

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Zero.

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Bernoulli is about Acceleration, not speed.

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Acceleration between two different locations along a single flow – ACCELERATION.

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You clearly do not understand the difference between speed and acceleration, nor how it applies to Bernoulli’s Principle.

.

This is the MOST fundamental aspect pf Bernoulli’s Principle that you and so many other people fail to understand.

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In addition, Bernoulli’s principle describes an Increase in speed that is ACCOMPANIURED BY a decrease in pressure, without explaining WHY this occurs. Therefore, it “explains” nothing. It only describes WHAT happens, not WHY.

. .

If you want something I learned by reading - -

John D, Anderson clearly states that there is nothing in Bernoulli’s notes to indicate he understood *WHY* this happened. Euler is credited with figuring out the why – and that is that a Pressure Gradient in a fluid is the cause of fluid acceleration just as a net force on an object is the cause of the objects acceleration, per Newton.

Cause and effect defined. .

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Then. . . what is in my Quora Blogs is what I learned from reading, discussing and observing demonstrations. . . It is all there.

QED.

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You don’t understand it and yet expect to be able to explain the physics and criticize others.

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You expect me to be offended when you don’t understand the SINGLE most fundamental aspect of Bernoulli’s Principle.

I’m not.

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BTW: YOU asked ME to tell YOU who I read and I answered Your question, adding people I talked to. . I answered YOUR follow-up question to mine.

.

Whereas, you say you read ONE book.

‘

QED.

.

.. .

. . .

I’m sorry, but you don’t understand Bernoulli’s Principle and refuse to.

If you refuse to understand this physics, I cannot help you learn.

.

Good luck in things you decide to do - - but do well, and be proud of doing well.

. . . -- Steve -- (talk) 02:09, 18 July 2025 (UTC)[reply]

I did promise to identify another book I have read. Also, you asked if I have ever studied fluid mechanics. I first studied Fluid Mechanics in the early 1970s as one of the units in my third year of an Engineering degree course, and I have been closely associated with fluid mechanics in one form or another, ever since. That unit was primarily about incompressible fluids such as water. (The following year my unit in Applied Thermodynamics was primarily about compressible fluids, such as air, and included transonic and supersonic flows.)

Our textbook was "Fluid Mechanics" by Victor L. Streeter (University of Michigan), copyright 1958 and published by McGraw-Hill. I have the fourth edition. Section 3.7 is titled "The Bernoulli Equation". In this section Streeter says The constant of integration (called the Bernoulli constant) in general varies from one streamline to another but remains constant along a streamline in steady, frictionless, incompressible flow. These four assumptions are needed and must be kept in mind when applying this equation.

Notice the emphasis on the streamline. Streeter makes no mention of solid surfaces, tubes, ducts or pipes. By implication, he is saying that wherever a fluid flow can be described by streamlines, the total energy of the flow can be determined at each point by Bernoulli's equation, providing the flow is steady, frictionless and incompressible.

In multiple places in section 3.7 Streeter quotes the Bernoulli equation in its common form: one term for kinetic energy, one term for pressure energy, and one term for gravitational potential energy. Immediately following equation 3.7.4 Streeter says: ... for gas flow, since elevation changes are frequently unimportant and [the term for gravitational potential energy] may be dropped out. As was the case in "Mechanics of Flight" by Alfred Kermode, Streeter acknowledges that in gas flow, changes in elevation are small when compared with changes in pressure and velocity. In my experience, books dedicated to aerodynamics and aeronautics always omit the potential energy term. However, this is only valid in the areas of gas dynamics and aerodynamics. In fields such as civil engineering, hydraulics, irrigation and hydroelectric power generation, the potential energy term is highly significant and no thought can be given to its omission. The Wikipedia article on Bernoulli's principle is not confined to aerodynamics or gas dynamics; it is intended to cover the principle in its most general form which must accommodate changes in gravitational potential energy at different points along any streamline.

You have challenged the validity of my example of a stream of water in free fall at atmospheric pressure. Streeter's Example 3.6 (page 116) presents a problem involving the horizontal flow of water in an open channel. The bottom of the channel changes elevation significantly. In solving the problem, Streeter considers two points on the surface of the water (so the pressure at both points is equal to atmospheric pressure.) By applying Bernoulli's equation, Example 3.6 concludes that the drop in elevation of the bottom of the channel is 22 feet. Streeter clearly has no objection to applying Bernoulli to a flow of water that experiences a significant change in elevation while its pressure remains unchanged and equal to atmospheric pressure. The book contains multiple similar problems for the student to work through. Answers to all even-numbered problems are provided at the back of the book. It is an excellent book on fluid mechanics and, despite the passage of more than 50 years, I still refer to it occasionally. Dolphin (t) 13:13, 19 July 2025 (UTC)[reply]

I don't see how that addresses the very specific point in my last. I'll make it easier.

.

Can you state, for me, your overall view regarding this 2 minute video by a PhD at Weber State U:

.

https://www.youtube.com/watch?v=ORd2pgKbM6M

.

? -- Steve -- (talk) 00:20, 20 July 2025 (UTC)[reply]

I watched for about 2 minutes. I wish it was shorter! It is nonsense!

I saw the gentleman blowing over and around pieces of paper and saying "high velocity, low pressure" or similar words. He ends up saying "Another application of Bernoulli" or similar words. All of that is, of course, nonsense.

Bernoulli's principle is applied to the steady, streamline, flow of frictionless fluids. A plume of air coming out of a person's mouth and interacting with a narrow piece of paper does not qualify as a streamline flowfield. The pressure and velocity within the plume of air bears no particular relationship with the pressure of the atmosphere (air) surrounding the plume. There are many examples of plumes of air and streams of water interacting with curved surfaces, such as a piece of paper or the convex surface of a spoon, and the plume or stream changes direction to follow the curved surface. However, this is not Bernoulli's principle. BP is simply conservation of mechanical energy within a steady flow of a frictionless, incompressible fluid.

I have been reading UALC closely and I'm interested in Figure 7 - a diagram showing vectors viewed in the still-air reference frame. UALC says Credit to Kim Aaron of JPL for making these measurements. Details on how it was done provided on request. Could you provide me with the details on how it was done? Thank you in advance.

The still-air reference frame is rarely considered but it does shown up some surprising and paradoxical observations, particularly in relation to Bernoulli's principle. For example, the still-air reference frame is not steady flow so Bernoulli is not applicable. Consider a small parcel of air within a stationary atmosphere. Its velocity is zero and its pressure is atmospheric pressure. Then along comes an airfoil or a ball or a bullet etc. Our small parcel is impacted by the moving object and briefly is part of the region near the stagnation point on the front of the object. Its velocity increases to the speed of the moving object, and its pressure increases to stagnation pressure. Zero velocity and atmospheric pressure quickly increase to high velocity and stagnation pressure - that defies Bernoulli's principle! Shortly afterwards, the small parcel of air returns to zero velocity and atmospheric pressure.

Lecturers sometimes ask students to explain this apparent violation of Bernoulli. The answer is that the still-air reference frame does not qualify as steady flow, nor does it qualify as streamline flow because most of the atmosphere is stationary and there are no true streamlines. Consequently Bernoulli's principle is not applicable and it is incorrect to suggest the observation violates Bernoulli. That is why the still-air reference frame is considered only rarely. Dolphin (t) 12:20, 20 July 2025 (UTC)[reply]

I’m sorry if this is a bit long, but I had to cover examples of how you go in wrong directions. . .

I get to the Ron Galli blowing-over-paper video below. . .

. .

I’m sorry, but you are constantly making errors in comparing different conditions, principles and units.

. .

On 2 May 2025 in the Wiki Bernoulli’s Principle article’s Talk section, you stated that Bernoulli’s Principle is explained by 4 cases, one of which stated:

.

2. “Each change in speed is associated with a change in height (or head or gravitational potential energy) of equal magnitude but opposite sign. This is the case of the thin stream of liquid falling through the atmosphere.”

.

First, changes in height and speed cannot have their *magnitudes* compared as being “equal” (but opposite in sign). They are completely different units. A speed magnitude of 3 km/sec is not equal in magnitude to a drop in 3 feet, or 3 inches. Magnitudes of distance and time cannot be compared. We could simply change the units we choose and the number magnitudes will change.

.

A change in speed cannot be equal in magnitude to a change in height. NOPE.

In fact you make that same error in all three of those cases. . .

. .

However, the *magnitudes* of potential and kinetic *energy* can be compared that way, BECAUSE under Bernoulli-friendly conditions, the energies only exchange forms, so the total is constant. However, that is not what you wrote.

.

Which, by the way, _IS_ what Bernoulli is about – the *exchange* between potential and kinetic energies along a flow (streamline).

. . . .

Second, perhaps I wasn’t clear earlier.

.

The falling stream is constantly being accelerated by gravity, thus ADDING kinetic energy. Whereas, Bernoulli deals with CONSTANT TOTAL energy. That is what “conservation of energy” means – NONE is added, nor removed.

Therefore, this is clearly NOT a distinct case that is “necessary to comprehensively explain Bernoulli”. Your #2 does not belong.

. . . .

Now, above YOU state that the faster air above a wing shows that pressure is lower than the air below the wing.

However, you then say that in Prof Galli’s video is nonsense.

BUT HE clearly forces air faster over the top of the paper.

Contradiction.!.

…

Then, WHY does his paper rise? What is the correct physics? The answer is coanda and then entrainment.

. . . . .

. . . .

Well. . . As I stated earlier, Bernoulli is NOT about speed, but acceleration. When you fully understand this, then that will make sense.

. . . .

THEN, we (should) also know that speed/velocity is dependent on the observer’s inertial frame of reference, but acceleration is not.

Therefore, a change in inertial frame of reference from that of the wing to that of the air-mass should show the same physics - - AND IT DOES.

.. . .

So. . .

. . .

That Figure 7 is from Cambridge Prof Holger Babinski’s video showing the smoke puffs in a wind tunnel.

The frame-by frame motions of the two smoke streamlines nearest the wing top and bottom, are converted to the still-air / moving-wing frame of reference, by using the highest smoke puff as representing the free stream speed to the right.

Kim Aaron measured those smoke location changes relative to the stationary air reference. The vector lengths are the frame-to-frame location change of those smoke streamlines as the wing flies by; thus representing velocity in the “still air” inertial frame.

. . . . . .

When you understand the physics fully, Figure 7 makes perfect sense and obeys the SAME laws of physics we see in the wind tunnel.

Knowing that physics can’t be different from different inertial frames of reference, Kim offered to do the work on that conversion when I said that I wondered what those motions look like.

.

TO BE CLEAR: This directly refutes your statement that:

“the still-air reference frame is not steady flow so Bernoulli is not applicable.”

YOU cannot claim that the physics changes with a change of inertial frame of reference.

Yes. . . aerodynamicists say that you can’t CALCULATE the moving wing case because it is not steady state - - BEACUSE it is a MUCH, MUCH , MUCH more difficult calculation to do and we find ways to make it easy - - AND that is *WHY* wind tunnels provide correct information EVEN THOUGH _THEY_ operate in the opposite reference frame. . .

.

In addition, to also be clear, Stating that:

“faster air above a wing shows that pressure is lower than the air below the wing”

is also false.

. . .

In other words, if you believe that wind tunnels “work”, Then, whether you realize it or not, you are assuming both reference frames show correct physics. If Bernoulli ‘works’ in a wind tunnel streamline, it MUST ALSO work for a moving wing to fly. . .

.

You can’t have it both ways – you are contradicting yourself when you say that Bernoulli doesn’t “work" in the moving wing view. . . . .

You have erred.

.

Seeing how the upper air is first pushed forward then completely stopped and reversed in direction to travel in the OPPOSITE direction of flight was very instructive.

The lower air is, however, CONSTANTLY accelerated in the direction of flight and reaches a forward speed greater than the upper air’s reverse speed.

.

IN ADDITION you should also see that the upper air is Accelerated more than the lower air – YES, more. This is from the greater horizontal Pressure Gradient from leading edge to above the wing’s low pressure. (Euler).

. .

It is easy to see in Figure 7 that the third upper vector is longer than the third lower. . .

THUS. . . the LOWER air is faster, but higher in pressure.

. ..

.. .

Also note that the lower air winds up far from where it started.

However, the upper air gets yanked back to near where it started. The small difference in the ending and starting locations of that upper air is related to the drag .. . AND . . . That fact mentioned in one or more of the texts I read.

.

Seeing Fig 7 was something that cemented a solid understanding of what’s going on around a wing for me, as well as for Kim, a PhD in aerodynamics as JPL. It makes perfect sense when you understand all the applicable physics.

. . . .

I also refer you to another work from 1982 showing a sub-set of those very same moving-wing air motions here:

. . . .

George Collinge Moving wing air motions:

EAA Sport Aviation April 1982 Pg. 52 Lift and Thrust, Part I of 4 figure 11 Moving wing air movements. His drawing STARTS after up-wash near Leading edge. I haven’t researched how he got that data, but it agrees with Kim’s data - - -AND physics.

http://acversailles.free.fr/documentation/08~Documentation_Generale_M_Suire/Aerodynamique/Portance/Lift_and_thrust.pdf URL OK March 2025:

EAA Sport Aviation Index 1980s showing Collinge articles.

http://www.cozybuilders.org/ref_info/sportavi80.html

. . . . . .

I’ve done my best to get you on the right track, but you have an unusual way of looking at things and until you see it yourself, I don’t think I can explain any better.

.. . . .

This is my last posting on this.

Regards. -- Steve -- (talk) 12:40, 22 July 2025 (UTC)[reply]

In response to my request for information in relation to one of your claims, you sent me a link to a French document at acversailles.free.fr. Unfortunately what I see is Error 404 - document does not exist.

I will appreciate it if you send me the explanatory data you offered “on request.” Dolphin (t) 06:59, 24 July 2025 (UTC)[reply]

A Google search on the title shows it on that site, but it appears the site recently pulled that article and it doesn't turn up on the Internet Archive WayBack Machine either. . .

I believe EAA members have access to past articles, but I can send it.

.

EAA Sport Aviation April 1981 Pg. 52 Lift and Thrust, Part I of 4 by George Collinge

See the Index only listed here April 1981:

http://www.cozybuilders.org/ref_info/sportavi80.html

.

FYI: The text ONLY for the article appears here, but the Fig 11 is key:

Text only Part 1: https://pdfhall.com/lift-and-thrust-part-1-of-4_5b70e184097c47d6068b4682.html

. . . . .

Since I don't own the copyright on the figure from the article, Wiki won't let me legally paste it here.

.

I have a copy of that article. I'll email it to what ever address you like.

. . .

. -- Steve -- (talk) 22:26, 24 July 2025 (UTC)[reply]

Thanks for that information. Regarding my email address, if you go to my User page by tapping my green signature “Dolphin”, in the top left-hand corner you will see a column of options. There is a category called “Tools”. The sixth option is “Email this User”.

Thanks for the tip regarding the four Collinge articles. I have copies of those. Dolphin (t) 00:05, 25 July 2025 (UTC)[reply]

If you have them, then just look at the figure and text around Part 1's, Figure 11.

.'

Just keep in mind that his time clock begins just as the wing leading edge gets to those two air bits.

Whereas, My fig. 7 starts a bit BEFORE the wing gets there and you see up-wash of both the upper and lower air parcels..

- - - - -- Steve -- (talk) 01:32, 25 July 2025 (UTC)[reply]

Good grief. You can't give me your email address and save me the trouble of fighting with the Quora interface?

Email me and I'll send the article to you. It is just a confirmation showing upper and lower air motions, similar to my Figure 7.

noskrap99@yahoo.com

. . . -- Steve -- (talk) 17:36, 25 July 2025 (UTC)[reply]

Wrong click. . .

. . .

Good grief. You can't give me your email address and save me the trouble of fighting with the Quora interface?

Email me and I'll send the article to you. It is just a confirmation showing upper and lower air motions, similar to my Figure 7.

noskrap99@yahoo.com -- Steve -- (talk) 17:43, 25 July 2025 (UTC)[reply]

Bernoulli’s principle II

Thank you for the email with the 1981 document by George B. Collinge. It was a groundbreaking article in 1981 and was my introduction to the concept of “cleavage” to describe the way the upper and lower streams are split by the airfoil and are never reunited.

There is an excellent animated diagram on Wikipedia, showing the way each time line in the upper flow arrives at the trailing edge ahead of itself in the lower flow. See Lift (force)#The wider flow around the airfoil. Your Figure 7 is consistent with this animation. You can see clearly that a particle that moved close to the upper surface is forever a short distance to the right-hand side of its partner that moved close to the lower surface. Dolphin (t) 06:55, 27 July 2025 (UTC)[reply]

So, are you saying that you had previously seen the Collinge articles?

Cleavage is an acceptable description. . .

. .

What is your view on this?

We know that if we put a wood block on a table, there will be sliding friction between the two surfaces.

Is that friction a scalar or vector?

-- -- Steve -- (talk) 23:24, 11 August 2025 (UTC)[reply]

Yes, Back in 1981 one of my engineer colleagues gave me a photocopy of the 4-part article by Collinge in the EAA magazine. I have stored it with my collection of useful photocopies ever since.

Collinge has labeled Figure 28 “Cleavage and phase shift”. The word cleavage seems a very appropriate word in this situation. Doug McLean uses the expression “branch cut” instead. See “Understanding Aerodynamics - Arguing From Real Physics”, Section 7.1. In particular, see Figure 7.1.2.

I have your email asking about a wooden block on a tabletop. I have responded to that one by email. Dolphin (t) 08:24, 13 August 2025 (UTC)[reply]

Sure, but I don't see the term carrying any significance in this discussion.

.

His figure 11, as far as it goes, shows a reasonable subset in agreement with my Fig 7 - that is all I was pointing to - along with the claim that when well understood, the same physics applies to either inertial reference frame; as it should.

. .

However, following up:

.

I can guess that he uses 'cleavage' to emphasize that equal transit is false, as described in the Dayton Air Force Museum at that time, and his two 'layers' are separated / cleaved, not to rejoin as they originally were. He does use 'slice' in the text.

. .

I don't know when it was seriously determined that equal transit was false. Amateurs still parrot it ad nauseam, including Neil deGrasse Tyson. I have wondered how/where Collinge got his information.

.

and

.

I have heard it speculated that equal transit may have come from the drawings of Prandtl on boundary layers; where his well-known drawing shows no 'phase shift' between the upper and lower flows. SO 'cleavage' seems to carry that idea. However, I see no use of that word in the text, so the focus is unclear without a reference explaining it in the text.

-- -- Steve -- (talk) 23:41, 14 August 2025 (UTC)[reply]