Posted Mon, 20 Aug 2018 15:17:06 GMT by Felix

I want to have the rate flow on the bottom of an excavation, is it possible to modelize this type of problem with feflow7.0 ? Water comes only by the bottom of the excavation because the limit of the excavation is impervious (modelize by conductivity = 0 m/d, as on the schema).

Is there someone able to help me ?


Posted Tue, 21 Aug 2018 07:21:25 GMT by Björn Kaiser
If you impose Dirichlet Boundary Conditions (fixed heads or seepage faces) you can use the corresponding nodes for budget calculation. Use the Rate / Period Budget panels or the Budget History Charts.

The Subdomain Boundary Rate / Period Budget panels only work if the excavated area is not represented by inactive or deleted elements.
Posted Wed, 22 Aug 2018 06:08:08 GMT by Peter Schätzl
Rather than a conductivity of 0 should use inactive elements or a very low k value.
Posted Thu, 23 Aug 2018 07:56:52 GMT by Felix
Thanks a lot for your advices.

Björn, I have imposed Dirichlet condition in the excavation. I have used Subdomain Boundary Rate Budget on the bottom of excavation and I have found my answer :)

Peter, I have used a very low k value but I don't understand why k=0 doesn't work.  ???  Can you give me more details please ?

Thanks again.
Posted Thu, 23 Aug 2018 13:10:59 GMT by Björn Kaiser
That's purely related with numerics. Pyhsically, K values of 0 m/s means no flow. The only way to represent no flow is to deactivate elements. In a physical context, the deactivation of elements and K values of 0 m/s is the same. From the internal computation point of view it's different.
Posted Mon, 27 Aug 2018 13:44:03 GMT by Felix
Thank you Björn for your explanation.

Some others questions :
When I run the model in Vertical, axisymmetric, the Subdomain Boundary rate budget give me 1845 m3/d. But when I run with a 3D model the Rate budget is 2674 m3/d. Do you knom where come from the difference ?

Moreover, why the Area or Lenght are so small ? (The well's radius is 8.3m) ???

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