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In addition, the code was reorganized to support multiple models within one MODFLOW run, as needed for the LGR (Local Grid Refinement) capability. [9] MODFLOW-2005 is written primarily in Fortran 90 and C, with C being used for one solver. The current version of MODFLOW-2005 is version 1.12.00, released on February 3, 2017. Related or branched ...
An example of a non-discretized radial model is the description of groundwater flow moving radially towards a deep well in a network of wells from which water is abstracted. [7] The radial flow passes through a vertical, cylindrical, cross-section representing the hydraulic equipotential of which the surface diminishes in the direction of the ...
Example 1 The linear-reservoir model (or Nash model) is widely used for rainfall-runoff analysis. The model uses a cascade of linear reservoirs along with a constant first-order storage coefficient, K , to predict the outflow from each reservoir (which is then used as the input to the next in the series).
Adaptive mesh refinement (AMR) changes the spacing of grid points, to change how accurately the solution is known in that region. In the shallow water example, the grid might in general be spaced every few feet—but it could be adaptively refined to have grid points every few inches in places where there are large waves.
Steps in numerical modeling. The first step in numerical modeling is to capture the actual geological scenario quantitatively. For example, in mantle convection modeling, heat equations are used to describe the heat energy circulating in the system while Navier–Stokes equations describe the flow of viscous fluid (the mantle rock).
Adaptive multigrid exhibits adaptive mesh refinement, that is, it adjusts the grid as the computation proceeds, in a manner dependent upon the computation itself. [18] The idea is to increase resolution of the grid only in regions of the solution where it is needed.
The terms "mesh generation," "grid generation," "meshing," " and "gridding," are often used interchangeably, although strictly speaking the latter two are broader and encompass mesh improvement: changing the mesh with the goal of increasing the speed or accuracy of the numerical calculations that will be performed over it.
The simulation time is generally proportional to the number of triangles, and so one wants to minimize the number of triangles, while still using enough triangles to give reasonably accurate results – typically by using an unstructured grid. The computer uses Ruppert's algorithm (or some similar meshing algorithm) to convert the polygonal ...