GSoC2020, FEM: extend examples

About the development of the FEM module/workbench.

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uwestoehr
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Re: GSoC2020, FEM: extend examples

Post by uwestoehr »

HoWil wrote: Fri Aug 05, 2022 5:37 pm A/editing the sif: this was not finished because keeping track of changes is hard. If change the geometry/mesh than the simulation will (most probably) fail. For sure it is a one-way 'story'. Changes in the sif can't be read to FC.
I cannot follow you. As it is now in master (and for 0.20.1), the workflow is this:
1. Press the "Write" button
2. Press the "Edit" button
3. edit the case.sif as you like and don't forget to save your changes using Crtl+S
4. press the "Run" button

This works fine. For example when I change the mesh scaling, I get the desired result mesh size. So the solver takes the edited case.sif.

The beauty is that you this way can do everything now wit Elmer. For example add a solver setting not yet supported by FreeCAD etc.

You can change the case.sif as you like, so this is already freetext input.
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Re: GSoC2020, FEM: extend examples

Post by HoWil »

8-) I do believe you that this works as you describe.
The problems start if you modify your fc-model. That is the reason why someone would use FC with Elmer, you want to create and modify the geometry (and mesh) easily. Otherwise, if your geometry is rock solid than you should use Elmer-GUI because than you have much more (I even think all solver-) options available.

But the reason for building the bridge between Freecad and Elmer was that in FC the design and the adoption of the geometry is much easier and that should not stop after the first creation of a simulation and export+edit of the sif.
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Re: GSoC2020, FEM: extend examples

Post by uwestoehr »

HoWil wrote: Fri Aug 05, 2022 6:37 pm 8-) I do believe you that this works as you describe.
The problems start if you modify your fc-model.
Try out FC 0.20.1 in about a week 8-)

see no problem, because I have a real-life use case with the flow equation and FC does not yet support all settings one needs.
I change the geometry
- I let FC write the case.sif
- I edit the case.sif
- I run the solver by pressing the "run" button

Works fine. Ind it is not too much work to copy in the same statement when I change the geometry.

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There still maaaany issues in Elmer support. However, the basics work now.
What I miss and where i have not yet an idea on how to implement is the usual loop:
1. set geometry
2. run solver
3. change a geometry parameter
4. run solver
5. if the result goes in right direction
6. change the geometry parameter the same direction a bit more

Step 4. to 6. should be automatized and end when the the result does no change anymore.

But before I work on this, I'll try that one can perform _all_ officially tutorials. I guess this will be months.
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Re: GSoC2020, FEM: extend examples

Post by bernd »

freetextinput is really cool. I would love to have this on CalculiX too. That was one of the reason it was not merged fast into master. I wanted somehow to have a look if it would be possible to make it somehow more generally.

BTW. Is there a own forum topic for the free text input. If not we should start one an put links to the post in the regard of elmer freetext input code.
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Re: GSoC2020, FEM: extend examples

Post by HoWil »

bernd wrote: Sat Aug 06, 2022 6:32 pm I would love to have this on CalculiX too. That was one of the reason it was not merged fast into master. I wanted somehow to have a look if it would be possible to make it somehow more generally.
Making it generally usable would be a big plus.
bernd wrote: Sat Aug 06, 2022 6:32 pm BTW. Is there a own forum topic for the free text input. If not we should start one an put links to the post in the regard of elmer freetext input code.
No. not now.
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Re: GSoC2020, FEM: extend examples

Post by uwestoehr »

bernd wrote: Sat Aug 06, 2022 6:32 pm freetextinput is really cool. I would love to have this on CalculiX too.
It seems i misunderstood the issue tghen because for CCX we have the same feature as now for Elmer:
- Write .inp file
- Edit it as you like
- run Solver

OK, during editing one cannot search & replace but what I understand as freetext input works.
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Re: GSoC2020, FEM: extend examples

Post by uwestoehr »

here is the explanation for the body heat issue:
https://www.elmerfem.org/forum/viewtopi ... 031#p27031

So since the heat equation has the second derivative of the length in it, we get the factor 10e6.

However, we cannot just scale the results back because when the input is too small, then there will not be a temperature difference that can be scaled for the final result.
The only way is to scale the body heat for the case.sif.

However, before we do this, we must be sure the body heat is correctly input to the heat equation by Elmer. Just 10 mW/kg is an incredibly low heat power:
https://www.elmerfem.org/forum/viewtopi ... 035#p27035

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In general, many thanks @raback for your support!
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