STABILITY OF THERMOSOLUTAL CONVECTION IN DEEP FLUIDS

This study examines the onset of thermosolutal convection in a semi-infinitely deep fluid layer. Using linear stability theory, we derive marginal stability curves for stationary and oscillatory convection through analytical methods, displaying numerical results that illustrate the effects of parameter variations on the critical Marangoni number, oscillation frequency, and wavenumber. Key findings reveal that in pure thermocapillary cases, stationary convection begins at a zero critical Marangoni number and wavenumber, while thermosolutal convection occurs at a nonzero wavenumber, influenced by the stabilizing solutal Marangoni number. For oscillatory convection, the Crispation and Lewis numbers destabilize, whereas the Biot number enhances stability, contrasting with the destabilizing solutal Biot number.