ABSTRACT
Non-aqueous pollutants are one of the important sources of soil and groundwater pollution. Due to the complexity of geological conditions and pollutant properties, it is difficult to obtain an accurate solution through analytical methods, so a numerical model needs to be established. Based on the interaction mechanism of water, air, and NAPL in porous media, a finite element numerical model was established to describe the migration of NAPL pollutants in the soil unsaturated zone, and the corresponding Fortran program Mig-3PF was written. Based on the mathematical model of groundwater seepage, the partial differential equations for the control of immiscible pollutants in the ground are deduced. The governing equations take into account the compressibility of air and adopt a mixed expression form of saturation and pressure. The numerical difficulty brought about by the distinct non-linearity of the temporal evolution of saturation-dependent variables is overcome by the mixed-form formulation. The process of discrete solutions using the Galerkin finite element method is described in detail. Finally, the NAPL Simulator and the self-written code Mig-3PF are used to simulate and compare the same example, which preliminarily verifies the correctness of the self-developed code.
