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Showing content with the highest reputation on 10/22/2009 in all areas

  1. 1 point
    1. Variable flux bcs in steady state model: I think what FEMWATER is doing is figuring out whether flux is inward or outward at each node. It could be outward if the water table comes near the surface so that net flux is outward. For some reason it (perversely) initially assumes it is outward everywhere. 2. Slow convergence: I found the cause behind my slow convergence was poor resolution in the van Genuchten curves. GMS produces curves that have poor resolution at the dry end of the curve. If you have the FEMWATER spline interpolation switched on, this can then produce curves that are non-monotonic I think, which screws up convergence. It worked better for me when I dramatically increased the number of points in the VG curves to 500 (I had increase MXSPMK and recompile FW to do this). Also note that the GMS preset VG curves are incorrect if your length scale is not centimetres. 3. Minimum pressure head: I think the only purpose of this parameter is to truncate the pressure head at the surface to limit how dry it can get, to avoid running off the end of the VG curves for instance. I am assuming this is only applied at the variable flux bc nodes but I am not sure.
  2. 1 point
    Hi Sreekanth I am not an expert on GMS observation wells, so I don't know whether you are describing a bug, but I can offer several comments: 1. FEMWATER does not have observation wells as such, so you have to output the solution for the whole mesh at every time step you are interested in. So it not very efficient at producing time series at a particular node. 2. It is fairly easy to run FEMWATER from another application. You can use GMS to set up the input (text) files initially, then FEMWATER can be run from the command line. Then you would need to extract the outputs you want from the FEMWATER output (text) files. 3. Another option is to modify the FEMWATER code to do the things you want. I have not done this, but I would say it would be straightforward for someone with FORTRAN programming experience. Simon
  3. 1 point
    Hi Sreekanth. You would be better to post this question as a new topic.
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