I came across this question while studying stalling of airfoils. How does the chord length of an airfoil affect the position of the separation point of flow?


The Wikipedia article on flow separation isn't very clear on what is the relation between location of separation point and Reynolds Number (and thus Chord Length).

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    $\begingroup$ Could you please link to the question? Without a link it is hard to know what you refer to. If you are unsure about linking: Click on edit, highlight the text and then call up the link dialog by clicking on the chain symbol on the bar above the edit box. Enter the link there and save. $\endgroup$ Commented Apr 6, 2016 at 7:12
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    – Jan Hudec
    Commented Apr 6, 2016 at 11:37

1 Answer 1


The chord length is a minor influence. The main driver for separation is the local pressure gradient.

Make sure to read the first three paragraphs of this answer if you are unsure how the pressure gradient drives separation.

The chord length only comes into play via the local Reynolds number. Higher Reynolds numbers mean steeper pressure gradients can be tolerated, but the effect is rather weak. It shows in the separation point which moves back slightly on the upper side of an airfoil near stall at the same angle of attack when the Reynolds number is increased.


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