Analysis of natural convection during solidification of a pure metal

A numerical study of solidification of gallium in a closed cavity is presented and the influence of natural convection on phase change is investigated. The mathematical formulation is based on the enthalpy-porosity method, while the equations are discretized on a fixed grid by means of a finite volume technique. Advancing in time is obtained using the SIMPLE algorithm, while the solution of the elliptic equation for pressure correction is obtained by means of a preconditioned BI-CGStab method. As a test case a square cavity with Ra ranging from 4.68 x 10(3) to 9.36 x 10(5) is adopted. Results will be presented in terms of streamlines, isotherms, solid-liquid interface position and Nu and compared, when possible with available data.