Flow Separation of Airfoil in terms of Reynolds Number

[Red_CCF]

Not necessarily. The separation point depends on the state of the boundary layer which depends on the Reynolds number. Increasing the Reynolds number from 10^3 to 10^7 will almost certainly change where the flow separates on an airfoil, because the state of the boundary layer will change. The transition point may move or the laminar separation bubble will no longer form and the flow will separate at the trailing edge instead. Keep in mind you can change the Reynolds number and the separation point may not change, it all depends on how the change in Reynolds number influences the boundary layer. And over a range as large as that it will likely change quite a bit. And of course to make things more complicated all of this depends on geometry and surface quality and various other factors. The same increase in Reynolds may dramatically effect the performance of one airfoil but not change it at all for another.

Boneh3ad mentioned that the flows in this range are fundamentally the same which is true. They are both dominated by inertial forces but that does not mean the details of the flow are the same.

Hi thanks very much for the response

Am I correct in saying that one can see separation point changing with Re in real life but such an effect is not due to the change in Re but other changes that are typically associated with flows as Re increases (assuming flow is in the laminar region), thus there is actually no theoretical relationship but only a correlative effect? Also, in the instance you described, is there a "typical" direction in which flow separation point moves?

Thanks very much

 

[Brettcm]

Hey guys I have a questions on the Reynolds number and you seem to be pros on the subject could you help me out.

https://www.physicsforums.com/showthread.php?p=4126078#post4126078

Thanks!