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. AH 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 update 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. Thereafter, the developed techniques were used to compute a g-jitter case with time-dependent variation of gravity to 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.