THERMOCAPILLARY AND OSCILLATORY-SHEAR INSTABILITIES IN A LAYER OF LIQUID WITH A DEFORMABLE SURFACE

The thermocapillary and shear-induced instabilities of a thin heated l ayer of liquid bounded from the top by a deformable free surface and a t the bottom by a horizontally oscillating plate are studied for both Earth-bound and microgravity conditions. Finite-wavelength thermocapil lary convection can be stabilized very significantly by the oscillator y shear, whereas sheer-induced instabilities are greatly stabilized if the Marangoni number is negative. For long-wavelength thermocapillary convection, oscillatory shear can stabilize or destabilize the basic state, depending primarily on the imposed forcing frequency. With micr ogravity, significant stabilization of the dominant long-wavelength co nvection can be achieved by carefully selecting the imposed frequency.