FRAC-UNIX theory and user's manual

摘要

The FRAC-UNIX computer code provides a two-dimensional simulation of saturated flow and transport in a fractured porous media. The code incorporates a dual permeability approach in which the rock matrix is modeled as rectangular cells and the fractures are represented as discrete elements on the edges and diagonals of the matrix cells. A single head distribution drives otherwise independent flows in the matrix and in the fractures. Steady-state or transient flow of a single-phase fluid may be simulated. Solute or heat transport is simulated by moving imaginary marker particles in the velocity field established by the flow model, under the additional influence of dispersive and diffusive processes. Sparse-matrix techniques are utilized along with a specially developed user interface. The code is installed a CRAY XMP24 Computer using the UNICOS operating system. The initial version of this code, entitled FRACSL, incorporated the same flow and transport models, but used a commercial software package for the numerics and user interface. This report describes the theoretical basis, approach and implementation incorporated in the code; the mechanics of operating the code; several sample problems; and the integration of code development with physical modeling and field testing. The code is fully functional, for most purposes, as shown by the results of an extensive code verification effort. Work remaining consists of refining and adding capabilities needed for several of the code verification problems; relatively simple modifications to extend its application and improve its ease of use; an improvement in the treatment of fracture junctions and correction of an error in calculating buoyancy and concentration for diagonal fractures on a rectangular grid. 42 refs., 28 figs., 5 tabs.