Onset Of Solutal Convection In Liquid Phase Epitaxy System

摘要

The onset of convective instability in the liquid phase epitaxy system is analyzed with linear stability theory. New stability equations are derived under the propagation theory, and the dimensionless critical time τ_c to mark the onset of the buoyancy-driven convection is obtained numerically. It is here found that the critical Rayleigh number Ra_c is 8000, below which the flow is unconditionally stable. For Ra>Ra_c the dimensionless critical time τ_c to mark the onset of a fastest growing instability is presented as a function of the Rayleigh number and the Schmidt number. Available numerical simulation results and theoretical predictions show that the manifest convection occurs starting from a certain time τ_o(> τ_c). It seems that during τ_c≤ τ≤ τ_o secondary motion is relatively very weak.