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Re: [Question #698948]: Stability of advection modeling by ThermalEngine


Question #698948 on Yade changed:

    Status: Answered => Open

Zoheir Khademian is still having a problem:
Hi Robert and thanks for the response.

>>What changes have you made in comparison to the example script? 
1- Turning internal compaction off in the triaxial engine and compacted the sample by inwards-moving walls.
2- Reducing the particle density from 2600e10 to 2600 to run the triaixal engine. 
3- Setting bodies dynamic false after compaction so there is no movement.
4- Turning off the thermo-mechanical analyses in thermal engine.
5- flow.bndCondIsPressure=[0,0,0,0,1,1] ; flow.bndCondValue=[0,0,0,0,0,10]
6- changing rRelFuzz from 0.333 to 0.33 #Small changes in the packing can make the model unstable like changing (mn,mx) a bit.

After making these changes, when I run, the model maximum body and fluid
temp exceed the boundary temp after 2 s.

>> I would apply more traditional boundary conditions a bit to confirm that you can reach stable states for your setup:
I changed the boundary conditions to the traditional ones as you suggested but it did not make any difference in stability.

>>You can take some manual control with thermal.minimumFluidCondDist[1].
I tried assigning different values (0.0015 to 0.015) to minimumFluidCondDist[1] but it did not make any difference.

>>However, you should also be able to figure out if that is the issue by simply turning on and off thermal.fluidConduction.
I turned off thermal.fluidConduction  and it solved the instability. I checked the centers of neighboring cells and some of them had pretty close X or Y or Z coordinates (less than 1e-5). Is this the issue? If so, could you give me some hint on how to avoid this issue. 


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