The Effects of Zone Volume and Gravity on Thermo-Solutal Marangoni Convection Instability in a Half-Zone Model of Float-Zone Growth of SiGe

A series of three-dimensional numerical simulations have been carried out to examine the onset and characteristics of thermo-solutal Marangoni convection in the floating liquid bridge of SiGe (Pr=6.37×10−3 and Sc=14.0). To this end, a simple half-zone model is considered, and the free surface deformation is taken into account. Simulation results carried out under normal (1-g) and zero gravity show that the computed temperature field in the melt is almost independent of this convective flow, and the concentration field determines the characteristics of the transport structures developing in the melt. The critical conditions for three volume ratios under normal and zero gravity conditions are determined. The thresholds in the liquid bridge depend on the volume ratio, and gravity has a negligible effect on the flow transition in the present calculation regime. The critical azimuthal wave number can shift to higher values at the higher volume ratio or to lower values at the low volume ratio. The random-periodic pattern was observed only at the high-volume ratio for the thermal-solutal Marangoni convection.