Study on Oscillatory Mechanism of Solutocapillary Convection and Influence of Aspect Ratio on Flow Characteristics during Crystal Growth

Abstract

A numerical simulation has been conducted to investigate the oscillatory mechanism of a solutocapillary convection and the influence of different aspect ratios on the flow characteristics in a liquid bridge. The SIMPLE algorithm is applied to figure out the Navier-Stokes equation and the concentration diffusion equation on the staggered grids, and the level set approach with the conservation of the mass is used to acquire the surface deformation of the liquid bridge. The flow characteristics of the oscillatory solutocapillary convection are analyzed in detail, including the distributions of the concentration, velocity, and transverse displacement of the free surface at the upper corner and intermediate height of the liquid bridge. Moreover, the effects of the aspect ratio on the flow stability and onset time of the oscillations for the concentration and velocity have also been investigated. The results show that the essence of the oscillatory solutocapillary convection is the result of the coupling oscillation of the concentration, velocity and free surface. The upper corner is the origin region of the oscillation, which has an important impact on the overall flow characteristics. Within a definite height range of the liquid bridge, the lower the height, the more stable the flow and the weaker the oscillation. There is a complex relationship between the onset time of the concentration and velocity oscillations and the aspect ratio of the liquid bridge.