摘要：This study focus on the 3D character of flow and the loss of symmetry that produces some unsteadiness and perturbs the shape and the dopant distribution in configurations interesting directional solidification. Only hydrodynamic in the melt is analyzed. The critical stability limited for the onset of the natural convection under 2D assumption is extended to a preliminary 3D investigation. It is found that the initial steady symmetric flow becomes asymmetric for lower Ra number in comparison to the 2D approach. The loss of symmetry occurs first in the transversal plan. For relative low Ra it is observed that the heat transfer increases on the bottom active wall and decreases on the vertical acting walls without significant intensification in the global transfer. The classical spiral characterizing the 3D effect of the surface limiting the domain is also observed.
