ABSOLUTE INSTABILITY OF RAYLEIGH-BENARD CONVECTION IN A TIME-PERIODICSHEAR-FLOW

The onset of thermal convection in an oscillatory shear flow is consid ered as an initial-value problem. For the case with zero mean shear, n umerical results indicate that the instability is absolute in nature, just as for the case without any shear. If a mean flow component also exists, then the instability tends to have the same nature as that whi ch occurs in the flow when no oscillation is present. (C) 1997 America n Institute of Physics.