An improved Picard iteration scheme for simulating unsaturated flow in porous media

The Richards equation is widely used in the simulation of unsaturated flow and related fields. In numerical solution process, finite volume method can be to carry out discretization, Picard for iterative solution. However, order obtain a more reliable solution, space step size conventional uniform grid often small. Especially under some unfavorable conditions, such as infiltration into dry soil layered with very different hydraulic conductivity, this will time-consuming even slow converge. Thus, combined non-uniform form Chebyshev, an improved based on two-grid correction scheme (NTG-PI) proposed model 1D porous media. Through three examples was verified. results show that, compared method, NTG-PI higher accuracy smaller number nodes, also has faster convergence rate. This provide certain reference flow.