Analytical models for simultaneous heat and moisture transport in soils

Basic equations are derived to describe the transport of heat and moisture in soils, in response to gravity, capillarity, and temperature gradients. Appropriate boundary conditions are given for cases where surface evaporation is limited by atmospheric conditions or by diffusion rates in the soil. Some approximate techniques which lead to linear equations are described. Analytical solutions are derived for four linear models. Numerical evaluation of the analytical solutions, using the program MOIST, is described, and the results are compared to those generated by a finite element solution technique applied to the governing equations. Analytical and numerical results showed excellent agreement.