Hydrothermal waves in rotating annular pools of silicon melt

Abstract

Influences of pool rotation on thermocapillary convection in shallow annular pools (ri=20 mm, ro=40 mm, and depth ranging from 1 mm to 3 mm) of silicon melt (Pr=0.011), differentially heated from the outer wall, are investigated by numerical simulations. In non-rotating pool, the hydrothermal wave (HTW) appears with characteristic spoke-like pattern. The spoke pattern is stationary or pulsating according to layer depth. However, in the rotating pool, curved HTW pattern propagates in the same azimuthal direction as the pool rotation direction, when observed from a fixed point in the rotating coordinate system. Most important effect of pool rotation is that even low pool rotation rate such as Ω=0.21rad/s weakens the HTW. Further increase of pool rotation rate up to Ω=0.52 rad/s can fully suppress the HTW in the pools of d=2 mm and 3mm, i.e., the pool rotation stabilizes the basic steady axisymmetric thermocapillary flow in annular pool of silicon melt against hydrothermal wave.