A computer simulation is conducted to study crystal growth of tubes by the floating-zone (FZ) method. Because the inner and outer radii of the steadily growing tube are unknown a priori and are coupled with fluid flow and heat transfer in the melt, solid/melt interfaces, and inner and outer free surfaces, the modeling of this process becomes rather difficult. A robust computer model based on the body-fitted coordinate finite-volume method (BFCFVM) and Newton's method with a preconditioned iterative linear equation solver is used to study the process. The effects of fluid flow and heat transfer on the solid/melt interfaces, free surfaces, and the dimension of the steadily grown tube crystal are demonstrated through computer simulations for both a high Prandtl-number material, i.e., NaNO3, and a low Prandtl-number material, i.e., silicon. The convection induced by both thermocapillary and buoyancy forces is considered. The effects of key process parameters are also discussed, including feeding/pulling speeds and the internally applied pressure.
