The Solum program for predicting temperature profiles in soils: mathematical models and boundary conditions analyses

Building simulation programs normally do not take into account moisture effects in soils temperature determination. However, the presence of  humidity can strongly affect the temperature distribution in soils due especially to the evaporation/condensation mechanisms and the strong variation of their thermophysical properties.In order to calculate the temperature profiles in  a more accurate way, we have developed the software Solum, which was conceived to model the coupled heat and moisture transfer in soils. The presented methodology is based on the theory of Philip and De Vries, using the thermophysical properties for three types of soil chemical composition. The governing equations were discretized using the finite volume method and a 3-D model was used for describing physical phenomena of heat and mass transfer in porous soils. The robust MultiTridiagonal-Matrix Algorithm (MTDMA) was used to solve the strongly- coupled problem. In conclusion, we showed the effects of boundary conditions for the soil such as solar radiation, water table and adiabatic and impermeable surfaces on the temperature and moisture content profiles.