Abstract
Probable convections in Czochralski crucibles are reviewed. Combined free and forced convection due to crystal rotation is analyzed in detail. The convection in the melt can be grouped into two classes: free convection dominance and forced convection dominance. Temperature field slightly depends on the convection in the melt with a low Prandtl number and is essentially determined by conduction. However, it depends on the convection for high Prandtl number melts and the interface shape is convex toward the melt if free convection is dominant and concave if forced convection is dominant. The abrupt change of the interface shape from convex to concave during the growth of some garnets is due to the fluid flow transition from free convection to forced convection. Two kinds of crystal shape instability are possible for high Prandtl number melts with a high Biot number. The effect of the crucible rotation on the convection in the melt is also examined.
