In this paper, we present a numerical model to simulate lost foam casting processes. We first introduce this particular casting in order to catch the different physical processes in play during a casting. We also briefly comment on the possible physical and numerical models to envisage the numerical simulation. Next we present a model which aims at solving “part of” the complexities of the casting, together with a simple energy budget that enables to obtain an equation for the velocity of the metal front advance. Once the physical model is established we develop a finite element method to solve the governing equations. The numerical and physical methodologies are then validated through the solution of a two and a three-dimensional example. Finally, we briefly discuss some possible improvements of the numerical model in order to catch more physical phenomena.