Moving packet model for variably saturated flow

Preconditioning Newton- Krylov Methods for Variably Saturated Flow

In this paper, we compare the effectiveness of three preconditioning strategies in simulations of variably saturated flow. Using Richards’ equation as our model, we solve the nonlinear system using a Newton-Krylov method. Since Krylov solvers can stagnate, resulting in slow convergence, we investigate different strategies of preconditioning the Jacobian system. Our work uses a multigrid method ...

Efficient Steady-State Solution Techniques for Variably Saturated Groundwater Flow

We consider the simulation of steady-state variably saturated groundwater flow using Richards’ equation (RE). The difficulties associated with solving RE numerically are well known. Most discretization approaches for RE lead to nonlinear systems that are large and difficult to solve. The solution of nonlinear systems for steadystate problems can be particularly challenging, since a good initial...

Locally conservative, stabilized finite element methods for variably saturated flow

Standard Galerkin finite element methods for variably saturated groundwater flow have several deficiencies. For instance, local oscillations can appear around sharp infiltration fronts without the use of mass-lumping, and velocity fields obtained from differentiation of pressure fields are discontinuous at element boundaries. Here, we consider conforming finite element discretizations based on ...

Convergent mass conservative schemes for flow and reactive solute transport in variably saturated porous media

Newton-Krylov-Multigrid Solvers for Large-Scale, Highly Heterogeneous, Variably Saturated Flow Problems

In this paper, we present a class of solvers developed for the parallel solution of Richards' equation, a model used in variably saturated ow simulations. These solvers take advantage of the fast, robust convergence of globalized Newton methods as well as the parallel scalability of multigrid preconditioners. We compare two multigrid methods. The methods di er primarily in their handling of dis...