Finite volume and spectral methods applied to Pb-30%Tl alloy solidification

Convection developing in the melted alloy Pb-30 % TI is studied under up-wa rd directional solidification conditions. Numerical investigation is based on the collocation Chebychev methods and the enthalpy-porosity formulation associeted to the finite volume approximation. The methods is able to descr ibe properly various convective solutal patterns and transitions according to gravity level (symmetric, asymmetric, time-dependent). Signature of on t he solidification front unsteadiness in terme of the striations is exibited .