STABILIZATION OF LONGITUDINAL VORTEX INSTABILITIES BY MEANS OF TRANSVERSE FLOW OSCILLATIONS

Longitudinal vortices with axes in the direction of a mean shear flow can arise due to body force instabilities associated with heating or c entrifugal effects. In this paper we are concerned with possible stabi lization or destabilization of such instabilities by means of a contro lled flow oscillation in the spanwise direction. For the heated case, stabilization occurs up to the values of Rayleigh and Reynolds numbers at which streamwise two-dimensional disturbances become critical. For the centrifugal case, stabilization occurs only for sufficiently larg e values of the Reynolds number associated with the spanwise oscillati on; for smaller values, destabilization occurs. (C) 1997 American Inst itute of Physics.