PolyRES: A Polygon-Based Richards Equation Solver

摘要

This document provides a description of a polygon-based Richards equation solver software package. The documentation assumes and the operation of the code requires that the user has a working knowledge of soil physics, numerical methods, and Fortran programming. The solver uses a finite volume approach and can model variably saturated (unsaturated-saturated) transient flow in two dimensions. The package is designed to allow the user to easily model polygon-shaped regions with flux, head, or unit-gradient boundary conditions. The region may be composed of one or more irregularly shaped objects for which the van Genuchten properties (van Genuchten, 1980a, 1980b) may be spatially variable or constant. The primary goals that guided the development of this software package were (1) complex geometries associated with barrier caps should be very easy for the user to specify and modify and (2) the execution of the water solver must be fast so it can be used to model large-scale problems over long time scales. The geometry of the problem, including the location of the boundaries, their type, and the shape of internal objects are defined through a simple user-supplied input file. The remaining input data, such as the transient behavior of boundary conditions, are provided through user-supplied subroutines. This provides the user with flexibility as to the type of problems solved. The computer code described in this document is available from the Energy Science and Technology Software Center, P.O. Box 1020, Oak Ridge, TN 37831-1020.