Study on Two-Dimensional Water Flow over and through Anisotropic Soil

Abstract

The two-dimensional (2D) hydraulic analysis of water flow down a slope is crucial. Contrary to past studies, not only the anisotropy of soil but also the vertical component of flow velocity are considered in this study. The flow field is divided into two regions, namely, the water layer and the anisotropic soil layer. By regarding soil as an anisotropic and permeable porous medium, the viscous flow theory and poroelastic theory are employed to govern the surface flow and subsurface flow, respectively. When considering the anisotropy of soil, hydraulic conductivity is supposed to be a second order tensor, and the momentum equations for the porous medium flow in the soil layer should be derived through a new method. Based on the presumption of velocity type, the distributions of horizontal and vertical velocity and pressure could be acquired by an analytical approach by the differential transform method. The results show that both the horizontal and vertical components of flow velocity increase with the anisotropy degree, whereas the pore water pressure decreases with the anisotropy degree. The streamlines in surface water flow depend on higher anisotropy degree. The infiltration rate for sand estimated by the present solution is feasible when compared with previous research result.