Oscillatory thermocapillary flow in silicon float zone under μ-g condition

The transient behaviors of the three - dimensional thermocapillary laminar flow which occurs inside a Silicon half zone have been thoroughly investigated. The molten liquid with its cylindrical free surface is assumed incompressible with constant physical properties except for its density in the buoyancy forces. The system of governing equations written in the (r, theta, z) coordinates system has been successfully solved by employing the modified-SIMPLE method. Results have shown that in general, both the flow and thermal fields do not change significantly with time during the heating process. Strong circulation of fluid is generally observed along the free surface while near the disks, high temperature and velocity gradients prevail. For relatively low Marangoni number, the now structure remains perfectly axisymmetrical. For sufficiently high Marangoni number, Ma greater than or equal to Ma(c) approximate to 80, the transition to the three dimensional oscillatory flow occurs. Such oscillations are believed to be due to some traveling disturbances waves on the free surface.