Application Of Characteristic Finite Element Method In Water Flow And Solute Transport Through Soils

Based on the project 《Numerical simulation for water flow and solute transport through soils》 supported by Science and Technology Creation Foundation of Xi'an University of Technology, numerical simulation for water flow and solute transport through soils by using the characteristic finite element method is mainly studied and some valuable results are obtained as follows:1. The numerical model of one-dimensional vertical water infiltration through unsaturated soils is constructed by characteristic finite element method. The mathematical verification for the numerical model is performed by the analytical solution to a special case. Based on the numerical model, the numerical simulation for a lab infiltration testing result is done and the modeling result is exact2. For the advection-dispersion model of one-dimensional reaction solute transport through soils with depth-dependent first-order degradation and depth-dependent linear equilibrium sorption under steady state flow, the numerical model is established by characteristic finite element method. Using the numerical model, the numerical calculations for the two supposed test cases are performed. Comparing to the quasi-analytical solutions, the errors caused by the numerical computation are much smaller. The numerical model can perfectly meet for the demand of calculating precision in practical work.3. For the two-region model of one-dimensional solute transport through heterogeneous soils considering scale-dependent dispersion and immobile region under steady state flow, the numerical model is obtained by characteristic finite element method. The numerical calculations for the supposedtest cases are done. The absolute errors between the numerical solutions and the quasi-analytical solutions are smaller and the numerical model can meet for the demand of practical work.4. The numerical model of one-dimensional solute transport through unsaturated soils is formulated by characteristic finite element method. The mathematical verification for the numerical model is performed by the analytical solution to a special case. Based on the numerical model, the numerical simulation for a lab salt-leaching testing result is done and the modeling result is exact.