3-D Groundwater Flow Modeling For the Oak RidgeReservation (ORR): Finite-Volume Method on AnUnstructured Grid System

摘要

In the design of in-situ bioremediation schemes, the flow near injection andrnextraction wells and recirculation units must be well understood. We describe arncomputationally efficient 3-dimensional finite-volume model for groundwater flow in arnheterogeneous layered anisotropic porous medium with dipping beds. This algorithm isrndeveloped applying the cell-centered finite volume method on an unstructured triangularrngrid system with fully implicit time discretization. According to the real hydrogeologicrnconditions of the Oak Ridge Reservation (ORR), we focus on aquifer layers with a 450rndip. The hydraulic conductivity is isotropic on a plane parallel to the layers, while thernthird principal axis, the one with the lowest value, is normal to the layers. The domain isrndiscretized into parallel dipping layers and each layer is discretized into triangles, thernsame at every level. The triangles are chosen using Delaunay triangulation techniques.rnThe use of triangles and adaptive technique makes this scheme more flexible and able tornaccurately represent a domain with wells and other geometric complexities. In thisrnscheme the total flux crossing each interface between neighboring control volume isrnapproximated by a one-point integration rule based on the specific discharge at thernmidpoint. At wells, realistic boundary conditions are used. Hydraulic conductivities arernderived from well tests using inverse methods. We show the flow regime near wells.