Abstract
Groundwater contamination previously occurred at a broad range of locations in present-day China. There are thousands of kinds of contaminants which can be divided into soluble and insoluble categories in groundwater. In recent years, the non-aqueous phase liquid (NAPL) pollution that belongs to the multi-phase seepage flow phenomenon has become an increasingly prominent topic due to the challenge brought by groundwater purification and its treatment. Migrating with seepage flow and moving into the potable water sources, these contaminants directly endanger people’s health. Therefore, it is necessary to research how these contaminants not only migrate, but also are then accordingly remedied. First, as an analysis means, an effective numerical method is necessary to be built. A three-dimensional finite element method program for analyzing two-phase flow in porous media, which can be applied to the immiscible contaminant transport problem in subsurface flow has been developed in this paper. The fundamental theory and numerical discretization formulations are elaborated. 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 effectiveness of simultaneous solution (SS) method and its improvement in efficiency are explained. Finally, two computational examples are given for verifying the correctness and demonstrating the preliminary applicability. In addition, the function of two-phase immiscible flow, especially in Fast Lagrangian Analysis of Continua (FLAC) is used to simulate the same examples and the results are compared to further verify the correctness of the numerical development.
Highlights
Different from the traditional of subsurface contaminant problems dominated by diffusion dissolved in water and convection miscible in fluid transport, in recent years, pollution of non-aqueous phase liquids (NAPLs), which belongs to multi-phase seepage flow phenomenon, is becoming increasingly prominent and complicated in the groundwater purification and treatment
This paper introduces the program development of the three-dimensional finite element method for non-miscible and incompressible two-phase flow and preliminary verification with two examples, which belong to LNAPL and DNAPL, respectively
In the proposed numerical method, the weak forms of mass balance equations for water, NAPLs were discretized in space using the Galerkin finite element method, and mixed-form formulations using both pressure water head and water saturation were adopted
Summary
Different from the traditional of subsurface contaminant problems dominated by diffusion dissolved in water and convection miscible in fluid transport, in recent years, pollution of non-aqueous phase liquids (NAPLs), which belongs to multi-phase seepage flow phenomenon, is becoming increasingly prominent and complicated in the groundwater purification and treatment. Such liquid pollutants are immiscible in water. A large number of gas stations and oil storage facilities have been newly built in many since the development of petroleum energy and chemicals play an important role in human industrial places in the world since the development of petroleum energy and chemicals play an important role production activities.
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