Application Of Multiscale Finite Element Methods In Groundwater Flow Of Heterogeneous Porous Media

The numerical modles are becoming an important method for the simulation of thegroundwater flow and solute transport problems,and now it have received more andmore attention and been used widely for its’ effectiveness,flexibility andcheapness.However the groundwater aquifer systems in the porous media are usuallycomplexed and highly heterogeneous due to the geology and the surroundings.Theheterogeneity is usually reflected by the multiscale fluctuations in the permeability ofthe aquifer.Therefore,when we use the traditional numerical methods(e.g.The FiniteElement Method or Finite Difference Method,etc.)to simulate these large scale areas,itmay be difficult to calculate.So all researchers are trying to find some new methods tosolve these multiscale problems with less computing resource and high calculationaccuracy.The Multiscale Finite Element Method(MsFEM) proposed recently is one ofthe most efficient methods.It can receieve acceptable solution in the coarse meshes.Thisthesis is also based on this MsFEM method，the main works are summarized as follows:Firstly,systemically summarized and introduced various numerical methods andtheir achievements in the groundwater areas.Although there have been many numericalmethods and commerical software for groundwater simulation,but about the MsFEMmethods there are not formed a complete software packages,thus it’s still essential todeveloped the programming for the MsFEM algorithm.Secondly,some details about the OpenGeoSys software are introduced.And thenthe new source programs are designed with the C++codes based on the OGSsoftware.The main part of the program is the implementation of the base function.Thenew programs are introduced into the OGS as a new model.Lastly,we build a two dimentional,saturated and steady flow model for flows in theanisotropic and isotropic porous media respectively,and a three dimentional model forthe isotropic porous media.The hydraulic gradient is relized by setting different valuesfor the boundaries.The comparison between the results calculated by the new program and the traditional method show that the new program can work well and it consumesless time,so the new program is efficient.This thesis is based on the OpenGeoSys software and built a highly efficientprogram to solve the saturated groundwate flow in the heterogeneous porous media.Itcan provide more accurate and efficient results and save time,so it has great potential ofapplication in the simulation of groundwater flow in the heterogeneous porous media.Ithas great theoretical sense and practical value to develop a software system to solve thegroundwater flow numerical modles with the MsFEM.