Characteristic Finite Element Methods And Application In Numerical Simulation For Water Flow In 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, theoretics and arithmetic of the characteristic finite element method for water flow in soils is mainly studied and some valuable results are obtained as follows:1. The characteristic finite element numerical model of two normal forms of 1~D Richards equations (with the variable are 6 and h in equation) are given, and error estimates are obtained, all this provide theoretical guarantee for later work.2. Under the conditions of infiltration evaporation and intermittent infiltration ,the numerical models of 1~D water infiltration through unsaturated soils are constructed by characteristic finite element method. The verification for the numerical model is performed by lab data or analytical solutions to special case. The modeling result is exact.3. For the 1-D water infiltration through homogeneous soils and layered soils, the numerical model is established by characteristic finite element method. And the numerical simulation is performed. It can be see from the results that the numerical calculation accord with actual laws, and numerical model can perfectly meet for the demand of practical work.4. A new form model equal to the Richards model is established. The advantage of the new model in constructing the characteristic finite element numerical model is discussed at last.