Thierry Dugnolle

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Potential flow around a circular cylinder with circulation

Hello Thierry! You have produced two absolutely wonderful animations of potential flow in 2 dimensions:

• zero circulation around a circular cylinder - see potential flow around a circular cylinder
• Kutta condition circulation around an airfoil - see Euler equations (fluid dynamics)

I greatly admire these two images and congratulate you for having produced them!

And now a request - would you produce a similar animation of potential flow with circulation around a circular cylinder? It would be an ideal addition at Magnus effect; and would also be useful at Lift (force) as a preliminary demonstration of the way upwash exactly matches downwash in 2-D flow around an airfoil.

I’m happy to discuss here on your Talk page if you wish. Best regards. Dolphin (t) 06:12, 4 March 2024 (UTC)

Thanks for your request. If a flow is with circulation, it can't be potential. TD (talk) 14:24, 4 March 2024 (UTC)

Perhaps I should change my request to “irrotational, inviscid, incompressible flow with circulation around a circular cylinder”.

The article Potential flow begins with a diagram of a NACA 0012 airfoil at 11 degrees angle of attack. The caption describes the image as “potential-flow streamlines” even though the streamlines display the Kutta condition. Should this diagram be removed from Potential flow; or should the caption be adjusted? Dolphin (t) 21:23, 4 March 2024 (UTC)

I don't know. About your request, may be I will make it, but it would be heavy work for me, because I lost my old code for these kinds of animations.TD (talk) 07:20, 5 March 2024 (UTC)

I understand your difficulty with new animations. The need I see on Wikipedia could be fulfilled by a simple diagram showing the streamlines but not being animated.

The sort of diagram I have in mind is visible on the internet. Here is an example:

Google for “Flow past a cylindrical obstacle Fitzpatrick”

You should get a hit on a document by Prof Richard Fitzpatrick of the University of Texas. Scroll down to the diagram of streamlines around a circle. Is such a diagram something you would be interested in producing? Dolphin (t) 06:29, 8 March 2024 (UTC)

Hi Thierry. I was perusing Talk:Magnus effect/Archive 1#Figure and found this image:

Dolphin (t) 00:51, 12 September 2024 (UTC)

Length contraction

Goog Morning @Thierry Dugnolle,

I think there is a trouble in your file File:Relativistic wheels.gif because the speed of the wheel, near to ground is about 0 and so little contraction, but near the top, velocity is about 0.994c and so great contraction.

The aspect of the wheel must seem like an egg (see for example File:Moss_ei_korrekt.svg), large at ground and small at top. The speed of the wheel is the relativistic sum of the velocity of center of the wheel and its rotational speed.

Thanks if you update your image.

Ming mm (talk) 07:19, 3 May 2024 (UTC) Ming mm (talk) 15:03, 8 May 2024 (UTC)

You're wrong. This animation is exact. You should learn more about the Lorentz transformation. A circle is transformed into an ellipse, not an egg.TD (talk) 22:44, 11 May 2024 (UTC)

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