Integration of automatic mesh generation for simulation of contaminants in soils and groundwater

摘要

An automatic mesh generator was modified and implemented that conforms to arbitrarily shaped two dimensional geometries. The grid generator requires no user intervention and can handle multiple component systems. The routine is well suited to dynamic situations experiencing large geometrical change such as in solidification or ground freezing processes. Additionally, the system has the option to output its results in a 2D Groundwater Modeling System format and a 3D extruded prism layer compatible with the GMS interface and the Waterways Experimental Station's 3DFEMFAT finite element code for flow and contaminant transport in saturated and unsaturated soils. A uniform equilateral triangular grid overlays the physical domain. Increased resolution can be specified in areas of interest or in areas undergoing large geometrical change such as occurs during solidification. All elements exterior to the physical domain are eliminated. The elements closest to physical boundaries are adjusted to conform to the physical shape, and a smoothing operator is employed to assimilate these adjustments. Interior boundaries of multiple component systems are retained. This mesh generation strategy virtually eliminates user interaction which reduces the actual time required for solution substantially. The adaptive finite element mesh generator was applied to an illustrative subsurface soil situation. Therein, the multiple levels of resolution are presented as well as the various output formats.