Talk:Prandtl–Meyer expansion fan

Smooth corner

In the first paragraph:

'In case of a smooth corner, these waves can be extended backwards to meet at a point'

Is this - '(all) waves . . . meet at a POINT' - always true? (I don't think it is: indeed, I'm reasonably certain that it is not). —Preceding unsigned comment added by 86.177.22.87 (talk) 22:43, 25 October 2010 (UTC)

This was corrected in the October 2014 edits, but for anyone wondering, this is only true for circular corners. 209.87.255.222 (talk) 20:45, 14 May 2015 (UTC)

Impossibility of expanding a flow through a single "shock" wave

In the image of an "expansion process through a single shock" shouldn't the w1 and w2 be perpendicular to the shock? --Joao30121998 (talk) 04:42, 10 April 2020 (UTC)

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Apparently this is a real physical thing that happens, so how can it have infinite parts?

We say that the Prandtl–Meyer expansion fan

consists of an infinite number of Mach waves...

and we use "infinite" a few other times. But other articles, such as Mach wave itself, use the term as if it's a real thing, and correct me if I'm wrong, but can real things have infinite elements, I would not think so? At Supersonic we have a picture with the caption

U.S. Navy F/A-18 approaching the sound barrier. The white cloud forms as a result of the supersonic expansion fans dropping the air temperature below the dew point.

Would it not take infinite time for the cloud to form if it's being caused by an infinite number of waves? All this is way above my pay grade, but I was confused, so if I am right, shouldn't we clarify that the term "Prandtl–Meyer expansion fan" is use for both a mathematical concept and a real thing that occurs sometimes when planess fly? Just saying. Herostratus (talk) 04:08, 11 March 2024 (UTC)