Role of Marangoni convection in Si-Czochralski melts, part Ⅰ: 3D predictions without crystal

摘要

Three-dimensional numerical simulations of flow field and heat transfer in a Czochralski crucible without crystal were carried out under pulling conditions. The study concentrated on the influence of the Marangoni convection in a silicon melt adopting a block-structured finite-volume code. The existing numerical code was extended to implement the surface tension boundary condition in order to investigate the influence of the Marangoni convection on the flow instability mechanism. The transient flow patterns reveal a significant role of Marangoni convection on the fluid mechanical instability at the free surface of the melt. A strong radial flow due to the presence of a surface tension effect is seen to increase the intensity of the buoyant plumes and enhance the net inward radial motion of the plumes. At later stages, the Coriolis force due to large crucible rotation suppresses the radial buoyant convection while substantial radial flow is observed in the presence of the Marangoni effect.