Talk:Aerodynamics

Bees in flight

Since people editing here probably know a little a about aerodynamics, it would be nice to have a section on the Bee article to discuss the flight of bees.

In part I'm asking because on Sunday Image:Bee mid air.jpg is due to be the Picture of the day|Picture of the Day. However, at the moment I'm not too happy with the caption as it is a bit too general - it would seem better to mention the common misconceptions about bees not being able to fly. -- Solipsist 09:13, 28 October 2005 (UTC)

I believe the statement is attributable to some of the earliest investigations into aerodynamics, notably the derivation of the lift equation, which is an empirical formula based on observation of aerofoil sections in wind tunnels. According to the lift equation, Bees supposedly can't fly because the wing area, lift coefficient and weight of the bee don't fit the equation. All this says is that the equation is inadequate for bee flight, since bees obviously can fly. However, for some reason this statement entered the popular imagination, which probably says a lot about the presentation and understanding of science by the wider population. As far as I recall, the mystery was only really solved quite recently, perhaps as recently as the 1990s - whereby new research indicates that insect flight takes advantage of a variety of dynamic effects such as the formation of vortices by the rapid wing vibration which cancel much of the induced drag. In addition, insect flight needs to be analysed at much lower Reynolds numbers than aircraft flight, since for the insect, the viscosity of the air is much greater relative to its size. That all said, don't treat this as a valid source, it's just what I can remember reading in the past. I'm sure you can find more reliable sources if you search. Graham 00:08, 30 October 2005 (UTC)

Birds and Flight

My science project seemed different in the begining but later changed, and influenced me to begin this. Birds fly using simple aerodynamics, gravity, lift, drag, and thrust. Gravity is what lets the bird come down if wanted. Lift is what helps the bird to lift off, from the ground allowing it to fly, like a plane. This also ties into thrust. Thrust is the bird moving it's wings to provid power to "lift" it off the ground. Finally drag is how much the bird ways. Weight is what holds it back. So it has to overcome gravity and drag to be able ot take off.

linking to other languages

Hello,

As the links to other languages section seems to be beyond the scope of editing, perhaps this is not the best place to bring this up, but I will anyway.

No, it's easy, you just needed to add a line to the source of the article in fact.WolfKeeper 07:55, 24 November 2006 (UTC)

I noticed there is no link to jp for aerodynamics.(空気力学) I thought this was a bit hard to believe, but in fact, there is no 'aerodynamics' page in Japanese. There is a redirect to the Japanese 'hydrodynamics' page.

流体力学 [1]

Until a Japanese 'aerodynamics' page is created, is it possible to request a ja link that also follows the redirect to the ja hydrodynamics page. Perhaps the ja editors feel that aerodynamics is covered sufficiently under hydrodynamics. I can't comment on the reasoning behind their development.

Thank you for your kindness.

- Rockthing 05:06, 24 November 2006 (UTC)

You don't need any special editing powers to do this. Anyway, I've added it for you, I did the obvious thing, and whilst I can't actually read the pages with my current browser settings it seems to have worked. Please confirm this, and by all means correct it if necessary.WolfKeeper 07:53, 24 November 2006 (UTC)

Ok, I see how you did it.

I didn't look far enough into the markup.

Thank you for taking care of it and sorry to

make work for you. Still a bit timid with editing.

The link is correct.

- Rockthing 13:59, 25 November 2006 (UTC)

spelling in continuity assumption

please correct it —Preceding unsigned comment added by 83.3.254.194 (talk) 20:36, 12 September 2007 (UTC)

Expansion

I'm going to spend some time expanding this page over the next month or so - I've already started with the history section. If anyone wants to help out or has issues/questions, leave them on my talk page. EMBaero 19:01, 30 November 2007 (UTC)EMBaero

[[ja:<something>]]

Gas dynamics

Perhaps all the great information in this article should instead appear in the Gas dynamics page. That way all the pages that link to this article from the word "aerodynamic", could instead link to Gas dynamics. —Preceding unsigned comment added by 24.22.24.208 (talk) 04:56, 17 February 2008 (UTC)

aerodynamics is bad homework —Preceding unsigned comment added by 82.44.66.65 (talk) 18:33, 30 April 2008 (UTC)

High level feedback

The only equation in the article is an incorrect one. Would it be unreasonable to have basic equations e.g. for lift and drag of a flat sheet, or something similar in the article? Right now, it's pretty devoid of technical content. —Preceding unsigned comment added by 24.128.191.214 (talk) 13:50, 7 January 2010 (UTC)

More sections needed

This article needs to have a section on aerodynamic friction & aerodynamic heating; and it also need one on computational aerodynamics. It would also be nice to at least mention the Navier-Stokes Equations. 98.81.15.87 (talk) 01:20, 9 September 2010 (UTC)

Article organization

Does this article need to be as long as it is? Stumbled across it in a return to Wikipedia (last time I was active was several years ago) and as an aerospace engineering student, I'm not entirely sure it is useful to a lay person. My thought would be to make sure the following sections/topics are covered, but perhaps move some of the more specialized discussion to their own pages:

• History of Aerodynamics
• Fundamental concepts/theory, ie: Lift/Drag/Thrust/Weight, Continuity, Conservation. Basic division of compressible vs. incompressible flow and subsonic/transonic/supersonic flow.
• Less fundamental theory: thin airfoil theory, etc. nothing too detailed, but on the level of developing some of the mentions of TAT and lifting-line theory in the History section a little more - ie defining these theories or saying what they are used for.
• Methods of study: experimental and computational, with both historical and current discussion.
• Current work: this, I think is a better title for "Associated Terminology" and is a good place to write about ongoing challenges such as solving the RANS equations

My concern is simply that the article organization currently is a bit haphazard. I would like to get some other editors' feedback and thoughts on improving the organization of the article. Corvus coronoides _talk 03:53, 29 July 2013 (UTC)

Major Edits

Since I haven't received any feedback at this point, in the spirit of WP:BOLD, I'm going to go ahead and continue doing some major overhaul to the article. This will begin with drastically cutting down the History section to being just a few paragraphs. In the meantime I'll move the History section to my sandbox, to be worked into its own article. If at any point other editors would like to weigh in and contribute, please do so! Corvus coronoides _talk 12:21, 30 July 2013 (UTC)

I don't have a problem with removal of material that is not attributed to a reliable published source. Removal of properly sourced material will be a problem. Such removal is likely to be reverted.

You have asked the rhetorical question Does this article need to be as long as it is? Presenting students or newcomers to any field with too much information all at once is not effective from an educational viewpoint but that is not relevant for an encyclopedia. Remember Wikipedia isn't a textbook. In any Wikipedia article, it should begin with simple, easily comprehensible material, and then progress to more advanced and complex material deeper into the article.

Moving material to its own article can be a reasonable approach when a separate article will qualify under Wikipedia's criteria for notability. But don't forget we are writing an encyclopedia, not a textbook. Dolphin (t) 22:24, 30 July 2013 (UTC)

Agreed, Wikipedia is not a textbook. My feeling on reading this article initially was that it read like a textbook, but the organization was confusing. My aim is to make it more encyclopedic, and if we run into any disagreements on what is encyclopedic I am happy to discuss. My reasoning for wanting to cut down on the History section was that I believed it had enough content to be its own article, and needn't take up so much space in this article, but again, that's up for discussion.

I believe the topic History of Aerodynamics qualifies for its own article under Wikipedia's criteria for notability. There are plenty of independent sources which are referenced in the original history section, and I have access to several others. Corvus coronoides _talk 22:42, 30 July 2013 (UTC)

I agree with your general approach bar one point, in that I do not think that the page is overly long as such. Some more detailed comments:

• I would restore much of the History material, but edit it down to remove any equations and some analysis that belongs in the main discussion. Also add a section on modern digital computation and its effects on the field. Only create a new article if this strategy subsequently fails.
• [updated] I like your addition of a Fundamental concepts section and would also explain here the basic division into incompressible (subsonic) and compressible (supersonic) flow, though again for the benefit of the non-mathematical lay reader I would avoid any equations and move them down to the main discussion. Having introduced the basic division, then very briefly define and link to special cases such as transonic, hypersonic and molecular (discontinuous).

— Cheers, Steelpillow (Talk) 08:10, 31 July 2013 (UTC)

Thanks for weighing in with your thoughts. At this point, the old history section can be found in my sandbox, where I had begun work to make it stand alone to be its own article. I agree with the need to add a section on modern CFD.

With the regard to whether or not it needs its own article, I propose that we leave the shortened History section in the actual article for now. After reorganizing the section in my sandbox, I'll ask for additional thoughts on whether it should be merged back into the main article or given its own. Would this be reasonable?

Well, I'd like to see the fuller History stay somewhere more findable than a user sandbox. How about creating History of aerodynamics for now and, if need be, later merging back and redirecting? — Cheers, Steelpillow (Talk) 13:48, 31 July 2013 (UTC)

You have a good point. I'll go ahead and make the article for now. Corvus coronoides _talk 14:02, 31 July 2013 (UTC)

Thank you. — Cheers, Steelpillow (Talk) 14:36, 31 July 2013 (UTC)

When you refer to "main discussion", do you imagine this taking place under the subheadings of "Branches of Aerodynamics" or somewhere else? Additional thoughts and comments are always welcome. Cheers, Corvus coronoides _talk 12:25, 31 July 2013 (UTC)

Yes, under "Branches of Aerodynamics" is essentially it, though that section may need to change focus if it expands to other aspects. — Cheers, Steelpillow (Talk) 13:48, 31 July 2013 (UTC)

Use of Equations

Another request for input. To what extent do other editors feel equations should be included and discussed in the article? I'm specifically looking at conservation laws. I think in order to address the main aspects of the topic it is important to have both integral and differential forms of the conservation laws, but the article as it stands also includes the simplified versions of the laws as applied to steady channel flow. I think these channel flow forms are useful as examples, but may be a little textbooky. What do others think about the following three options?

1. Cut out channel flow examples altogether - unnecessary for an encyclopedia article and adds clunkiness to the article.

2. Move channel flow examples into their own subsection (ie define all three conservation laws, then have a section where these are applied to the channel flow example).

3. Leave channel flow examples where they are, immediately following introduction of the conservation law.

I think my personal preference might be option 2. Corvus coronoides _talk 00:58, 9 August 2013 (UTC)

My own view is based on my experience as a professional technical author. Firstly, Wikipedia is not a text book. Every technical topic should be accessible to the non-mathematician. That means it needs to be explained in words, preferably supported by diagrams and illustrations. Equations are strictly for the specialist reader and for deeper technical analysis where editors feel their enthusiasm taking them. Equations need to be distanced at least a little from the introductory text. How this is done depends on circumstance. maybe just add the equation in a separate paragraph immediately following, maybe add a subsection for the equations, maybe add a whole new article for the specialist reader. In the case of the conservation laws here, I would suggest that these are more to do with dynamic modelling generally, perhaps in their narrowest sense with fluid dynamics rather than aerodynamics, and are very much out of place in an introductory article for the lay reader. So I personally would go for Option 1 "plus": drastically shorten the discussion in the present article but find a new home for the equations in another article (if they are not somewhere suitable already), possibly called something like Fundamental principles of fluid dynamics. — Cheers, Steelpillow (Talk) 10:31, 9 August 2013 (UTC)

Hmm. Well, we already have articles or article sections for the Navier-Stokes equations and the continuity equation. I haven't found an already existing mention of conservation of energy applied to fluid dynamics specifically, though. At first I thought Fluid dynamics#Equations of fluid dynamics might be a good home for these guys, but that would add a lot of math/text to that section, which is already fairly wordy.

I think it is good to have the most general forms of each of the conservation equations somewhere, just not sure where. I don't see a great place to put these, but what if we took most of the section as it currently stands and moved it to the Fluid dynamics article? You are right in saying that these equations are general fluid dynamics equations. It would probably make sense to put this discussion there and link to it here. Corvus coronoides _talk 14:18, 10 August 2013 (UTC)

Sounds good to me. — Cheers, Steelpillow (Talk) 19:47, 10 August 2013 (UTC)

Appropriateness of Further Reading section?

Hi there. The current "Further Reading" section is currently quite a lengthy list of useful reference texts - useful for professionals, but perhaps not for the general reader. What are other editors' thoughts on this section? I'm inclined to cut it out, per WP:NOT - not an indiscriminate collection of information, neither textbook nor teaching site, not a collection of links, but it's a big change so I'm soliciting other thoughts. Corvus coronoides _talk 19:10, 16 August 2013 (UTC)

Reading WP:FURTHER I would say that the list should be substantially trimmed, for example by deleting most works on sub-topics, but not deleted wholesale. — Cheers, Steelpillow (Talk) 10:40, 17 August 2013 (UTC)

Thinking further, any half-decent technical bookshop will have a modern textbook on aerodynamics. And there are so many textbooks around that any selection here will be PoV based and worthless. Then again, what one might call important "milestone" publications should be listed among the references. Not sure if anything will survive that amount of pruning, but still better to consider each case rather than delete wholesale. — Cheers, Steelpillow (Talk) 12:53, 17 August 2013 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Aerodynamics/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

=Aerodynamics&oldid=91577638 version reviewed Intro is too long, see Wikipedia:Lead section. No equations or pictures. I think it should have sections on the major aspects with links to there main articles, e.g. Basic Equations, Nozzles Diffusers and Wind Tunnels, Shock Waves, Mach number - Supersonic and Subsonic, Lineralised theory, Numerical Non-linear models (picking some topics from {{cite book}}: Empty citation (help)) No sources.

Last edited at 16:17, 2 December 2006 (UTC). Substituted at 06:47, 29 April 2016 (UTC)

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Bernoulli and gravity

Under Conservation Laws the article asserts "Additionally, Bernoulli's equation is a solution to the momentum conservation equation of an inviscid flow that neglects gravity."

This is news to me since Bernoulli's equation has a term for gravity. Granted it's sometimes omitted when gravity is not relevant, but it's a stretch to say that it neglects gravity.

I propose saying "Additionally, Bernoulli's equation is a solution to the momentum conservation equation of an inviscid fluid."

Comments? Mr. Swordfish (talk) 15:41, 24 July 2020 (UTC)

@Mr swordfish: I agree the statement that Bernoulli's equation "neglects gravity” is incorrect so I’m glad you removed these words.

On closer inspection I can see a couple of things that appear to be incorrect so it is likely that all these errors, including the bit about “neglects gravity” were inserted by the same User.

Firstly, under Conservation Laws it says “Momentum within a flow is only changed by the work performed on the system by external forces ...” As you know, there is no relationship between work and momentum. The two shouldn’t be mentioned in the same sentence! When the resultant force on a body does work it alters the kinetic energy of the body. The momentum of a body is altered by the impulse of the resultant force.

I don’t doubt that Bernoulli's equation can be derived using conservation of momentum but in Wikipedia, at Bernoulli's principle#Derivations of the Bernoulli equation, the equation is derived using the work-energy principle, not conservation of momentum.

Secondly, the sentence in question “Additionally, Bernoulli's equation is a solution to the momentum conservation equation of an inviscid flow” implies that momentum conservation is not valid for a viscous fluid. I think this is incorrect – simple consideration of kinetic energy, potential energy and the pressure of a fluid ignores friction (and viscous forces) because friction diverts energy to thermal energy. In contrast, conservation of momentum applies even when friction exists so I suspect all fluid equations derived from conservation of momentum are valid even in the presence of viscous forces. For example, the Navier-Stokes equations are applicable to viscous fluids and these equations are based on conservation of momentum.

So, in summary, Bernoulli's equation assumes the fluid is inviscid, but not because it is based on conservation of momentum. Bernoulli’s equation is only applicable to inviscid flows because it is a simple equation that is derived from consideration of conservation of kinetic energy and potential energy (pressure).

Perhaps the best solution is to further modify the sentence in question so it says Additionally, Bernoulli’s equation is a solution to the momentum conservation equation. Dolphin (t) 12:23, 26 July 2020 (UTC)

Thanks or your input. I've made a couple of modifications to the article implementing your suggestions.

Upon further examination, I see that the article claims that the conservation of momentum equation(s) is the Navier-Stokes equations; there seems to be some disagreement here, for instance NASA says that N-S comprises all three conservation equations ( See https://www.grc.nasa.gov/www/k-12/airplane/nseqs.html ) Another site claims "The Navier-Stokes equations represent the conservation of momentum, while the continuity equation represents the conservation of mass." and that they "...are always solved together with the continuity equation..." (https://www.comsol.com/multiphysics/navier-stokes-equations ) Meanwhile, wikipedia's article on N-S claims they "...are not conservation equations, but rather a dissipative system..."

I'm not sure how to sort out this mess. I've always thought along the lines of NASA that N-S was all three conservation laws, rather than restricting it to just the momentum parts. This is probably just a matter of semantics - some authors pick out the momentum part and label that N-S, others lump all six equation under N-S since all six are necessary to adequately model fluid dynamics.

I may take a stab at refactoring this section to reflect the differences between reliable sources as to what, exactly, the N-S equations comprise. Mr. Swordfish (talk) 15:55, 26 July 2020 (UTC)

I like the changes you have just made.

I have had a quick look at Euler equations (fluid dynamics) and I see they are based on consideration of momentum (and continuity) simplified by assumption of zero viscosity and zero thermal conductivity. I conclude from this that the Eulers occupy a mid-position between the simplicity of Bernoulli and the complexity of N-S.

Please continue with your effort to refactor the section to properly take account of N-S. Dolphin (t) 22:35, 26 July 2020 (UTC)

Confusion between Fluid Dynamics and Gas Dynamics

The relationship as I understand it is that fluid dynamics is the study of liquids and gases and the changes they undergo due to processes such as heat, movement, and pressure, and gas dynamics is a subfield of fluid dynamics.

I think the phrasing that aerodynamics is a subfield of fluid dynamics and gas dynamics is confusing because fluid dynamics includes the study of gases.

THis is my justification for rewording the lead. ScientistBuilder (talk) 02:19, 11 February 2022 (UTC)