UPF: two-dimensional finite-element groundwater flow model for saturatedunsaturated soils ?
A finite-element program for modeling water flow in saturatedunsaturated soils is presented. The program can handle non-uniform flow regions having irregular boundaries and local anisotropy. The flow domain can be either in a vertical or in a horizontal plane, or in a three dimensional system with radial symmetry. The flow equation is solved by using either a Galerkin finite-element (GFE), or a control-volume finite-element (CVFE) method. The discretization of the flow domain is obtained by using triangular finite elements and linear shape functions; the integration in time is performed by a finite-difference (FD) Picard scheme. Different schemes of the upstream and lumping procedures in computing, respectively, the conductivity and capacity matrices are compared, taking as evaluation parameters the global mass balance errors and the stability of the solutions. The listing of the FORTRAN 77 source code, along with the user manual, the description of the subroutines used in the code, and four input files for four test cases are available by anonymous FTP from ftp.iamg.org site or may be downloaded by Internet from http://www.iamg.org/CGEditor/index.htm.
numerical code unsaturated flow galerkin formulation control-volume finite-element model