Enthalpy based formulations for phase change problems with application to g-jitter

Alternative formulations for the computational modelling of phase change have been investigated in the context of single region enthalpy based mathematical models. All calculations were carried out on a fixed cartesian grid. Both, pure conduction driven phase change and buoyancy driven convective effects were considered. Two methods of phase fraction up-date were selected for detailed investigation - the H-based and the T-based methods. Numerical experiments using the one-dimensional conduction driven Stefan problem revealed that while both methods gave identical results, the T-based method was superior in terms of computational efficiency. The T-based method was then extended to compute phase change in the presence of buoyancy driven convection, and to compare with experimental information and assess its performance. Therefore, the developed techniques were used to compute a g-jitter case with time-dependent variation of gravity of simulate the environment encountered in an orbiting spacecraft. The effects of g-jitter on the predicted wall heat fluxes and on the interface shape and motion are discussed.