Computational analysis of Marangoni effects during floating zone growth under microgravity conditions
This study deals with the phase change problem in a floating zone configuration. A coupled approach treats the
thermo-capillary convection in liquid bridge and melting of the solid. A finite volume approximation is used with enthalpy formulation using a fixed grid for coupling melting of a pure material and thermo-capillary flow and permitting the resolution of multi-interfaces problem.
The effect of various imposed heat flux distributions on the free surface for axi-symmetric liquid bridge flows, in zero gravity, is presented. Interaction of the phase change with hydrodynamic transition is studied.
In steady state situation, the resulting velocity and temperature fields are compared between the classical only
liquid-bridge convection (planar front, without phase change) and the present coupled problem (phase changethermocapillary
convection). It is shown that the distribution of the applied heat flux plays an important role in both case of the full and restricted problem without phase change considerations. The free surface temperature is higher in the full problem. The effect of the imposed heat flux distributions on the free surface in the full problem shows that the solid/liquid interface curvature decreases with the heat flux concentration. This is essentially due to the increase in the flow intensity allowing better mixing.
It is found that the flow near the singularity line depends more on the total energy than on the flux distribution.
For the same total energy it's more sensitive to the imposed flux shape in the full problem in comparison with the
simplified one due to the coupling of the two subdomains.