A Finite Element Axisymmetrical and Linear Model of Two-phase Flow Through Porous Media

A two-dimensional (radial and vertical) transient finite element solution of two-phase air and water flow was developed to simulate unsaturated flow situations. Axisymmetric linear triangular elements were used to represent three-dimensional space. Governing equations were based on Darcy’s equation and continuity. Air was treated as a compressible fluid by using the Ideal Gas Law. Simulations are presented showing radial and vertical unsaturated flow and the effect of air compression on infiltration. The model was found to be sensitive to errors in the soil water retention curve and the relative permeability curve. The model was verified with laboratory data and the infiltration-inhibiting effects of air compression and air counterflow were simulated.