Articles techniques et présentations

This work describes the numerical resolution of a benchmark problem dedicated to the simulation of two-dimensional columnar solidification of binary alloys (Pb-Sn) with COMSOL Multiphysics®. The benchmark, defined in [1], aims at evaluating the ability of numerical models to reproduce coupled thermo-solutal convection and phase change phenomena occurring during ingot solidification. The problem involves a rectangular cavity initially filled with a liquid binary alloy, where solidification is induced by cooling from a vertical wall. Our numerical approach incorporates heat transfer, with an original enthalpy formulation, fluid flow, using Brinkman equation, and solute transport together with a solidification model based on volume-averaged conservation equations and thermodynamic equilibrium assumptions. The influence of numerical parameters such as time step size, mesh refinement, and discretization order is investigated to evaluate the stability, accuracy, and convergence of the simulations. Indeed, these parameters are shown to play a key role in capturing the strongly coupled thermo-solutal flow and the sharp evolution of the mushy zone. The obtained results demonstrate that COMSOL Multiphysics® is able to capture the main physical trends described in the benchmark. The numerical results show qualitative and quantitative consistent flow structures, temperature and concentration fields, as well as coherent solidification patterns described in the literature. In conclusion, this work highlights the capability of COMSOL Multiphysics® to provide relevant first-order predictions for complex solidification problems. These encouraging results constitute a solid basis for further improvements, including solidification model refinement and extended validation against experimental results.