A study of transport process of buoyancy-induced and thermocapillary flow of molten alloy

Two-dimensional numerical computations have been conducted to investigate the steady-state flow and transport characteristics of the buoyancy-induced and thermocapillary flow of molten alloy. The cases considered are for temperature gradient counteracting solute gradient of the binary mixture and surface tension. A finite volume type of approach utilizing the nonorthogonal curvilinear coordinates along with appropriate grid distribution is employed. Various combinations of the dimensionless parameters, including Marangoni number, thermal and solutal Grashof number, Prandtl number, Schmidt number, and aspect ratio have been studied. A wide variety of transport characteristics have been observed with respect to the change of these parameters, resulting in different numbers, sizes and directions of the convection eddies present in the flowfield. The strong effects of the fluid properties on the transport process are identified, indicating their relevance to the morphology of phase interfaces. For flow domain with nonunity aspect ratio, multiple steady-state solutions have been obtained.