Application Of Finite Volume Method In Soil Water-salt Flow Numerical Simulation

Unsaturated soils water is the connection of surface water and ground water, it is the source that the field crop living depends on. Studied field soil water- salt movement is particularly important to predict, reasonable irrigation and to develop water-saving agriculture in arid and semi-arid region.The numerical simulation is an important aspect of the scientific computation and engineering. A good numerical method — finite volume method (FVM) used to simulate the water-salt movement FVM has following advantages: First, integral conservation law can be satisfied every control and total calculation region. Therefore it shows the accurate integral conservation in case of coarse grid, the result of computation is comparatively accurate. Second, integral grid's partition is rather flexible. So some complicated boundary conditions could be treated conveniently.Based on the theory of soil water dynamics and solute transportation, one-dimensional vertical infiltration of unsaturated soil water movement and solute transport mathematical model is established. A numerical algorithm, together with its MATLAB code, of the mathematical model by using finite volume method is presented. The reliability of the mathematical model is verified by some experiments. The numerical simulation results are in accordance with the experimental results. The main work of the paper is as following:1 The numerical model of one-dimensional vertical water infiltration through unsaturated soils is constructed by FVM. Based on the numerical model, the numerical simulation for a lab infiltration testing result is done and the modeling result is quite satisfied.2 The numerical model of one-dimensional horizontal solute transport and vertical solute transport through unsaturated soils is formulated by FVM. Based on the numerical model, the numerical simulation for a lab infiltration testing result is done. It shows by comparison between measured and simulated results that numerical method for simulating soil water-salt movement in unsaturated soil is reliable and available.3 Through comparing finite volume method with finite difference method (FDM), it shows that FVM can avoid the phenomenon of numerical disperse and numerical shake which frequently happens in FDM. Therefore, for simulating soil water and solute movement, finite volume method is a good and practical numerical method in engineering application.