Posted Wed, 18 Oct 2006 19:48:25 GMT by Denim Umeshkumar Anajwala
Hi there,

I'm modelling  Steady Mass Transport (in 3D) using 1st kind Mass Transport Boundaries as a source.

To me, the expected result should be a plume moving downgradient from the source and ending at the lower head boundary, which is about 2 Km away from the source. This is supported by field observation on the plume shape. Actually, I've already modelled the same setting using FRAC3D and obtained such results.
However, the plume modelled using FEFLOW doesn't reach the boundary of the model: it simply vanishes somewhere halfway to reach 0 mg/L. Could someone explain this to me?

Here are some of the parameters I used in this model that might explain this behaviour:

Saturated media
Flow and mass transport (both are steady)
Recharge (In(+)/Out(-) flow on top): 8.2 x10-4 m/d (300 mm/yr)
Longitudinal dispersivity: 5m
Transverse dispersivity: 0.5m
Linear (std) dispersion
Diffusion: 1x10-9 m2/s
No decay or  Sorption

Solver settings: Preconditionned restarted ORTHOMIN... (since the defaults would not work)


Posted Thu, 19 Oct 2006 08:37:30 GMT by Boris Lyssenko
Sounds like a convergence problem. To check that, try to run the model in transient mode over a long time.
Posted Thu, 19 Oct 2006 19:18:59 GMT by Denim Umeshkumar Anajwala
Peter Schatzl: YOU solved my problem!
Many many thanks!

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