http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
three-dimensional finite element model to simulate groundwater flow of two immiscible fluids through anisotropic and heterogeneous media
A full three-dimensional finite element model to simulate groundwater flow under steady state conditions was developed. The model can be used for fluids of constant density and when two different fluids are separated by a sharp interface with the denser fluid immobile. The main characteristic of the model is that it can consider very anisotropic and heterogeneous media. The resulting system of equations is solved using the iterative Gauss-Seidel method. A pointer matrix used to save memory and computation time avoiding the storage of most of the zeros in the resulting sparse matrix. A simple automatic mesh generation algorithm was developed for eight nodes hexahedrical elements, together with an algorithm to represent the geology when the layers can be defined between planes with variable slopes along x and y axis. The model was verified against several analytical solutions available in the literature for simple groundwater solutions available in the literature for simple groundwater problems. From the sensitivity analysis, it was found that the relative size of the elements along the x, y, and z axis, the magnitude of the error used to stop the Gauss-Seidel iterative process, and the grid spacing are very important parameters which if not properly determined can cause the model not to run, or the model can give wrong solutions. Finally, the model was applied in the evaluation of a brine recovery wells system in the Dove Creek area in the upper Brazos River, Texas, where a natural salt pollution exists. From this evaluation, it was found that a system of ten recovery wells located in the Dove Creek Salt Flat is not enough to eliminate the natural salt springs and seeps. It was estimated that it is necessary to pump two cubic feet per second of brine to eliminate the natural salt pollution. The maximum pumping rate from the ten wells was 1.2 cfs.