A VISUAL STUDY OF VORTEX-INDUCED INSTABILITY ON A FLAT PLATE LAMINAR BOUNDARY LAYER

T.T. Lim, T.K. Sengupta and M. Chattopadhyay

Abstract

This paper reports a result of our experimental investigation on flow instability on a flat plate laminar boundary layer due to a <91>captive' vortex migrating far outside the boundary layer. Results show that the sign of the circulation associated with the vortex is the main determinant for the severity of the boundary layer instability. A counter-clockwise rotating vortex causes a violent breakdown ahead of it, while a clockwise rotating vortex gives rise to a weaker excitation trailing it. Additional parameters that influence the flow instability are the strength and distance of the vertical disturbance from the boundary layer, as well as the translational speed of the vortex.