A nested rediscretization method to improve pathline resolution by eliminating weak sinks representing wells.

F J Spitz; R S Nicholson; D A Pope

doi:10.1111/j.1745-6584.2001.tb02369.x

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A nested rediscretization method to improve pathline resolution by eliminating weak sinks representing wells.

F J Spitz·R S Nicholson·D A Pope

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Abstract

This paper discusses a method for overcoming the problem of weak sinks representing wells that result from spatial discretization effects when using MODPATH, the particle-tracking postprocessor for the ground water flow model MODFLOW. Weak sink cells are model cells that represent a well that does not discharge at a sufficiently large rate to capture all of the flow entering the cell; therefore, flowpaths within these cells cannot be uniquely defined because it is impossible to know whether a given water particle discharges to the well or passes through the cell. Creating a submodel of the well cell by using the nested rediscretization method can eliminate this ambiguity by converting the weak sink cell into a strong sink cell. The method is designed to be run manually for each well and for steady-state conditions. Other advantages, disadvantages, technical considerations, and limitations of the method are presented. Software created for the method consists of five Fortran programs that are operated using a set of instructions. A practical application of the method is presented by using an example wellhead-protection problem that demonstrates that nested rediscretization can provide more accurate particle-tracking results than those obtained by using a coarsely discretized model alone.

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F J Spitz, R S Nicholson, D A Pope. A nested rediscretization method to improve pathline resolution by eliminating weak sinks representing wells.. https://doi.org/10.1111/j.1745-6584.2001.tb02369.x

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