Aspect ratio and capillary ratio dependence of thermal-solutal capillary-buoyancy flow of a binary mixture in an annular pool

3D simulations are carried out to understand the aspect ratio and capillary ratio dependence of the thermal-solutal capillary-buoyancy flow in an annular pool. The annular pool was filled with silicon-germanium melt (C₀=1.99%). Results show that the axisymmetric stable flow occurs when the thermal capillary Reynolds number is small. The evolution of the flow pattern undergoes two and three stages with the aspect ratio and capillary ratio. Besides the special case of R_σ=-1, the critical thermal Reynolds number for the flow bifurcations into a 3D flow rises with the increase of the capillary ratio and decrease of the aspect ratio. Various three-dimensional flow patterns, including the lotus-like pattern, spoke pattern, hydrosolutal waves, ear-like pattern, growth-ring-like pattern and petal-like pattern, are observed, which are related to the capillary ratio, aspect ratio and thermal capillary Reynolds number. The wave number of the spoke pattern, hydrosolutal waves and petal-like pattern decreases with the aspect ratio, but rises up with the capillary ratio.