Perfect axisymmetry is difficult to achieve in the vertical Bridgman crystal growth. Nonaxisymmetry is, to a certain degree, always present in a real crystal growth configuration. To study how fluid flow and solute fields in the process are affected by slight deviations from axisymmetry, a three-dimensional finite-volume/Newton method is developed. Pseudo-steady-state heat and mass transfer, fluid flow, and the growth front are solved simultaneously. The calculated results for axisymmetric cases are compared with those by two-dimensional finite volume and finite element methods, and they are in excellent agreement. Calculated results also show that three-dimensional flow and solute fields are easily induced by imperfect axisymmetry. A slightly tilted ampoule or a small temperature gradient in the azimuthal direction could break axisymmetry and dramatically affect flow patterns and solute segregation.
