Prediction of transient oscillating flow in czochralski convection

Abstract

A numerical study is made of oscillatory flow modes in Czochralski convection. The growth striations in the crystal are known to be generated by a macroscopic oscillation of the flow in the melt. A time period of temperature fluctuation beneath a crystal rod is computed by varying the mixed convection parameter, $0.132\le Ra/PrRe^2\le1.303$ between buoyancy and forced convection in the rotating container. The simulated time period shows an excellent agreement with the relevant experiment. Parametric studies are performed in order to acquire an understanding of transition mechanism. Transient distributions of meridional flow and temperature are presented. The influence of the height of melt level and the size of crystal rod on the onset of oscillation are also examined and evaluated. The control of melt convection is also attempted by employing the laser beam projection.