Coupled Simulation Model for Ice Migration

Detection of exterrestrial ice or water is among the most important tasks for space exploration. The resources are invaluable to build permanent base on the Moon or on the Mars. There are different processes governing the migration, formation and accumulation of ice under exterrestrial environment. Especially, this involves coupling of multiple fields such as thermal, hydraulic and mechanical fields. This paper describes the development and implementation of a coupled thermo-hydro-mechanical model for unsaturated porous materials. The coupling integrates the Fourier's laws for heat transfer, Richard's equation for fluid transfer, and linear constitutive relationship. Coupled parameters were utilized to transfer information within or between field variables. Additional relationships, such as the similarity between drying and freezing processes, Clapeyron equation for ice balance were incorporated to consider the effects of frost action. Numerical simulations were implemented in multiphysical platform to solve the coupled nonlinear partial differential equations. A simulation case was carried out on a relatively simple geometry, using accepted models for thermal, hydraulic and mechanical properties. Results of multiphysical simulations, (such as the freezing induced moisture redistribution, the thermal stresses, etc) are consistent with the basic laws and experience. The results indicate under terrestrial environment, ground freezing will cause moisture to migrate toward ground surface. By incorporating the unique phase transition mechanism under exterrestrial environment, the simulation model can potentially be used to guide the exploration of water resources under exterrestrial environment.