Recent Posts

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MIKE 11 / MIKE 11 Engine - Floating point overflow error - AD model
« Last post by marthavive on Yesterday at 03:26:14 pm »
Hello

I am setting up a model in MIKE ZERO that includes Advection-Dispersion to simulate CST (with a single layer) but a floating point overflow error message crashes the model. I have tried changing all parameters in the AD file but nothing works.

Thanks
Martha
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FEFLOW / Re: HOw to retrieve the 43th diagonal?
« Last post by razipv on Yesterday at 07:00:56 am »
What is the reason for SAMG: Row(s) with negative diagonal found! ERROR
How can i rectify that?
         
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FEFLOW / Negative sorption coefficient?
« Last post by imanroohi on Yesterday at 04:42:01 am »
Hello all,

I have modeled a contaminant transport from a spill in feflow and got some results. My first setup was implementing no sorption. In second simulation, I applied k=0.2 as Henry (linear) sorption coefficient and surprisingly the concentrations were higher than initial case with no sorption, which is opposite to the expectation.
I tried k=-0.2 and the results make sense, but I could not find a reference to this. Anyone know if we actually should put the sorption coefficient in negative?
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FEFLOW / Re: Saltwater Intrusion numerical dispersion
« Last post by Laweewrun on November 08, 2019, 03:50:37 am »
It's the information I'm looking for as well.
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MIKE 21 / Re: PROGRAM MULTIPLE SIMULATIONS
« Last post by c.souto on November 07, 2019, 10:48:59 pm »
Thank you so much!
It worked!   ;D
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MIKE 21 / Re: PROGRAM MULTIPLE SIMULATIONS
« Last post by Sebastian on November 07, 2019, 03:08:06 pm »
Hey,

check this:
https://forum.mikepoweredbydhi.com/index.php/topic,1592.0.html
and
https://faq.dhigroup.com/default.asp?module=MIKE+21&ID=57#answer

Hope it helps!
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MIKE 21 / PROGRAM MULTIPLE SIMULATIONS
« Last post by c.souto on November 07, 2019, 12:03:11 pm »
Hello,

I would like to know if there's any way to program multiple simulations in order to let computer work all night and have all the results the day after.

Thanks in advance.
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FEFLOW / Re: How to define temporal BC in Expression Editor
« Last post by razipv on November 06, 2019, 12:32:49 pm »
any way to directly import precipitation to feflow and the change recharge according to each zones based on some percentage of precipitation?
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FEFLOW / Re: Saltwater Intrusion numerical dispersion
« Last post by Peter Schätzl on November 04, 2019, 04:25:33 pm »
You will most probably not be able to completely avoid negative values (even if the Péclet criterion is fulfilled), as FEFLOW will show them as they occur in the solution. The 'art' is to find the balance between stability and possible mesh resolution. From your description, the spreading over the entire system does not seem to be caused by numerical oscillations, but by the boundary conditions you have chosen. However, this is hard to judge from only a few lines of description.
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FEFLOW / Saltwater Intrusion numerical dispersion
« Last post by CP on November 04, 2019, 03:23:09 pm »
Hello everyone

I'm simulating a saltwater intrusion on a simple model which is set to be bounded by a hydraulic head BC by the western side and a saltwater head by the sea boundary (to the East). As far as regards mass transport boundaries, I have set a constant mass concentration BC by the sea boundary (35000 mg/l) and I am setting a saltwater inflow in the western boundary, only in the last two model slices (as my saltwater intrusion should cross all my model in the last two slices). However, when  starting simulating the mass transport I can't avoid oscillations and negatives values in the concentrations at the edge of the intrusion. Moreover, even if I set a saltwater inflow only in the last two slices, salt spreads all over the system by the end of the simulations. The mesh was set up to maintain a Peclet number of less than 1 given the dispersivity and I have also ensured that it had <5% obtuse triangles.  I've tried different upwinding techniques, but none of those remove the problem entirely either.  Also, I have tried a more gradual introduction of saltwater by varying the western concentration, but as soon as any saltwater enters the system negative values appear...

Any suggestion that can help to avoid these problems?
Thanks!!!
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