Comment on "Moving-Wall Effect on Unsteady Boundary Layer"

Abstract

I NRef. 1 an elegantanalysis is presentedwhich demonstratestheoretically that the moving-wall effect in uences the separation of the boundary layer on a stalling airfoil in the manner described in the discussion of Fig. 14 in Ref. 2. That is, the moving-wall effect will amplify the accelerated-ow effect on a pitching airfoil but counteract it on an airfoil describing a plunging motion. It would be of signiŽ cant interest if the authors were to extend their theoretical analysis to the one-degree-of-freedom three-dimensional  ow on a coning body of revolutionillustratedby Fig. 6 in Ref. 4. As has been demonstrated analytically, the self-induced coning of a body of revolution6 is generatedby a  ow mechanism fundamentally the same as that giving rise to dynamic lift overshoot on an oscillating airfoil. This is important in view of the fundamental role that this  ow phenomenon plays on a combat aircraft maneuvering at high angles of attack.7;8