* Institut de Mécanique des Fluides, UM34 du CNRs, 1 rue Honnorat, F-13003, Marseille, France
** U.N.E.D., Departamento Física Fundamental, Apdo. 60141, E-28080, Madrid, Spain
Abstract:
The paper is concerned with the numerical simulation and the analysis of some kinds of flow regimes which can develop in Bridgman and Czochralski systems for material processings. The flows in the liquid phase are investigated considering two-dimensional and axisymmetric models. The time-dependent regimes were studied for a zero-Prandtl-number fluid layer confined inside a two-dimensional cavity of aspect ratio (length-to-height) A=4, involving a stress-free upper surface and submitted to a horizontal temperature gradient. The range of Grashof number was varied up to the conditions at which the flow goes from oscillatory to chaotic type behaviours. The combined influence of the temperature gradients and of the rotations of the crucible and of the seed/crystal was investigated for a Czochralski model. The axisymmetric regimes were studied for a Prm=0.015 liquid melt confined inside a cylindrical crucible of aspect ratio (height-to-radius) Am=2, and coupled to a viscous encapsulant liquid layer (10<Pre<1200) of aspect ratio Ae=0.5. A number of steady and (transient) time-dependent flow patterns are identified.