Evolution of Heat Flow during Solidification of A356 Alloy: A Numerical Study

The direction of heat flow is a measure of the microstructure formation during solidification. This work accordingly investigates heat flow during the solidification of A356 alloy in a cylindrical cavity numerically using the finite volume method (FVM) and volume-averaged properties. A set of governing equations is used to represent the solidification process, including conservation of mass, momentum, energy and species. The corresponding numerical simulation is performed using the SIMPLER algorithm and the TDMA solver to investigate the solidification behaviour at different degrees of superheat, i.e., 90 °C, 135 °C, and 185 °C. It is found that the development of the solid-liquid interface is delayed to some extent under superheated conditions, following validation of the developed FORTRAN-based numerical code against existing literature. Subsequently, the heat flow in the domain during solidification is investigated. At the solid-liquid interface, the latent heat evolution results in an approximate 175-225×10 4 W/m 2 heat flux that flows normal to it in both directions of the interface, i.e., towards the solid and liquid phases. It is found that buoyancy-driven fluid flow also repositions latent heat within the domain, resulting in heat accumulation succeeding the domain flow pattern. A high heat flux is observed, reaching approximately 200 ×10 4 W/m 2 during phase change and decreasing upon completion of the solidification process. This heat-flow direction at the solid-liquid interface is a possible direction of dendritic growth.