b.dynamic=False in ThermalEngine example

Asked by Jiannan Wang on 2020-07-26

Hello,

I'm trying to learn through the thermal engine example in [1]. If I remove the b.dynamic=False: comments the section of [2], the temperature won't change (the temperature plot just becomes flat lines). What is the reason behind this?

The reason I'm asking is that I want to explore the thermal expansion effect on the strain changes of the body. Setting b.dynamic=False seems counterintuitive? Any tip? Thanks!

Best regards
Jiannan

[1]: https://gitlab.com/yade-dev/trunk/-/blob/master/examples/ThermalEngine/flowScenario.py
[2]: https://gitlab.com/yade-dev/trunk/-/blob/master/examples/ThermalEngine/flowScenario.py#L100-102

Question information

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Status:
Solved
For:
Yade Edit question
Assignee:
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Solved by:
Jiannan Wang
Solved:
2020-07-29
Last query:
2020-07-29
Last reply:
2020-07-28
Robert Caulk (rcaulk) said : #1

Hello,

Have you checked to make sure your spheres are still touching and are still in the location that you expect them to be ;-)?

Cheers,

Robert

Jiannan Wang (jnwang) said : #2

Hello Robert,

Yeah ... The spheres immediately disappear, even for the nonflowScenario [1] and thermoMech=False.

Also, in nonflowScenario [1], if I heat up one of the wall and set b.dynamic=False and fluidThermoMech=True, all the spheres, except the ones on the heated wall, disappear.

Where did I mess up?

Best regards
Jiannan Wangg

[1]:https://gitlab.com/yade-dev/trunk/-/blob/master/examples/ThermalEngine/noFlowScenario.py

Robert Caulk (rcaulk) said : #3

Typically disappearing spheres is a sign of an unstable time step. Which
makes sense since you are introducing elastic waves into the system, which
are likely resolved at a much smaller time step than the thermal component.
You can decrease the time step manually or you can use one of yade’s tools
to automatically compute the elastic wave time step. Let me know if It
works.

Le lun. 27 juil. 2020 à 23:35, Jiannan Wang <
<email address hidden>> a écrit :

> Question #692076 on Yade changed:
> https://answers.launchpad.net/yade/+question/692076
>
> Status: Answered => Open
>
> Jiannan Wang is still having a problem:
> Hello Robert,
>
> Yeah ... The spheres immediately disappear, even for the nonflowScenario
> [1] and thermoMech=False.
>
> Also, in nonflowScenario [1], if I heat up one of the wall and set
> b.dynamic=False and fluidThermoMech=True, all the spheres, except the
> ones on the heated wall, disappear.
>
> Where did I mess up?
>
>
> Best regards
> Jiannan Wangg
>
> [1]:https://gitlab.com/yade-
> dev/trunk/-/blob/master/examples/ThermalEngine/noFlowScenario.py
>
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Jiannan Wang (jnwang) said : #4

Hello Robert,

Thank you for the help. I decrease the time step down to 1e-12, and it is finally working. If I use dt = 1e-12 for few iterations, i.e. 500 iterations, and then switch back to 1e-9, seems also OK.

But all this only work on the exact pack file in the example (sphere file in [1]). I try to create my own pack, with roughly the same dimension and parasitical radius, still cannot get it works (even with dt = 1e-30 ...). Is there something I missed on the packing side? I attach a MEW packing script:
############
from yade import export

young=1e9
tt=TriaxialTest(StabilityCriterion=.001, compactionFrictionDeg=radians(3),internalCompaction=True, radiusMean=-0.004,numberOfGrains=1000, upperCorner=(0.05,0.05,0.05),lowerCorner=(0,0,0),thickness=0.01,radiusStdDev=0.3,sigmaIsoCompaction=-10000,maxMultiplier=1.+2e4/young,finalMaxMultiplier=1.+2e3/young)

O.run(20000,1)
export.text('CubicPack.spheres')
############3

Best regards
Jiannan Wang

[1]: https://gitlab.com/yade-dev/trunk/-/blob/master/examples/ThermalEngine/5cmEdge_1mm.spheres

Robert Caulk (rcaulk) said : #5

I am happy to help you but please can you adhere to our forum guidelines [1]?

In particular, please notice number 5:

"Do not merge different questions in one single post, even if - in your mind - they are connected to one single project. If your question received satisfying answer(s), mark it solved immediately. Do not use the same thread to jump to another question, open a new question instead."

Additionally, when you do create a new thread for this new packing question - it will certainly need more details elaborating on your single piece of "information" provided:

"still cannot get it works"

Thanks,

Robert

[1] https://www.yade-dem.org/wiki/Howtoask

Jiannan Wang (jnwang) said : #6

Hello Robert,

Thank you for willing to help, I'll open another thread.

Best regards
Jiannan