Marangoni flow in floating half zone of molten tin

Gravity affects the stability of Marangoni flow in floating half zone of low-Pr fluids through two different factors, i.e., the buoyancy and the static deformation of the free surface shape. In the present study, influence of these two factors are evaluated by unsteady three-dimensional (3D) simulations for a realistic model of floating half zone of molten tin (Pr = 0.009) with an aspect ratio As = 2.0 under a ramped temperature difference (1.19 K/min) between the top and bottom ends of two iron supporting rods. The corresponding first critical conditions for the onset of 3D asymmetric non-oscillatory flows and the second critical conditions for the onset of 3D oscillatory flows are determined. Simulation results indicate that the fee surface deformation is the most influential factor for the critical conditions of the flow transitions. Buoyancy is less influential to the flow transitions. However, buoyancy causes multiple step transitions between different 3D asymmetric non-oscillatory flow modes.