NONLINEAR WATER DIFFUSION IN UNSATURATED POROUS SOLID MATERIALS

Water diffusion in unsaturated porous solid materials is investigated in the present study. The hydraulic diffusivity of water diffusion is seen to be adequately represented only by a highly nonlinear water content-dependent function. The nonlinear physical model can be efficiently tackled by the orthogonal collocation method. Numerical simulations of the water diffusion model in various porous solid materials arc shown to agree well with the experimental observations. The physical model with nonlinear water content-dependent hydraulic diffusivity can be employed to predict the behavior of water movement in the unsaturated porous materials.