Comparison of Finite Volume Methods for the Solution of Advection-Dispersion Equation in Unsaturated Porous Media

Document Type : Original Research

Authors
Department of Civil Engineering, K.N. Toosi University of Technology
Abstract
Due the limitations and lack of access to fresh water resources, groundwater is recognized as an important source. In this research, a novel method called Dual Discrete Finite Volume (DDFV) has been developed for modeling flow and contaminant transport in saturated and unsaturated porous media. In this method, structured and unstructured grids have been used to handle complex geometries. Flow and contaminant transport equations have been accurately modeled for each triangular element in the grid. This modeling process yields contaminant concentrations at the center and vertices of each element. First, the flow equation in an unsaturated medium has been solved. Parameters such as moisture content and hydraulic head have been calculated. Then, based on the obtained results, the water velocity in the soil was estimated. Finally, the contamination equation in an unsaturated medium was extracted, and the concentration values at the vertices of each element were calculated. This model has been validated for transient flow conditions with high accuracy. By comparing the two-dimensional case with the one-dimensional case, it was determined that there are no numerical oscillations in the two-dimensional case.

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