Hello Guys,
Im trying to do a coupling simulation with OpenFoam and Calculix to simulate the thermic stress. I used the Heat Exchanger tutorial to build up my Case.
There is one Problem, in every simulation there is one node with a Temperature of 0 Kelvin, The Same in the Heat Exchanger tutorial. Does anyone know how to get rid of this anomaly? My Case stops because of too many cutbacks and i think this anomaly is one problem.
Hopefully someone can help me.
Kind regards!
Hello Ramon,
I might not be of much help since I don’t have any experience running CHT cases with CalculiX, but is by chance the node with T = 0 K node number 1 (in CalculiX)? I might have an idea if it is.
Regards
Andrés
Hello Andrés,
first of all:
thanks for the fast Answer!
i’ve looked it up and you are right, in both cases it’s the node number 1 with the 0K.
For that reason i tried to integrate an initial BC for this node and tried to integrate a normal BC for the node numer 1 but the result was the same.
Do you have an idea what could be the reason?
Best Regards
Ramon
Sounds related to:
I understand that this is related to the setup of the CalculiX case. Interesting that it also appears in CHT!
Hey Ramon:
I had a hunch that was the case. Something similar happens in FSI cases, where node number 1 stays fixed even though there are no displacement BCs imposed on it.
The solution (workaround) you are looking for is not to use number 1 for any of your nodes. Start numbering your CalculiX nodes from 2 onwards. In your case, if n is the number of nodes in your mesh, then renumber node 1 to n+1. Don’t forget to update that number in your *ELEMENT keyword (i.e. for those elements for which that node is part of) and in node sets it belongs to.
@Makis Indeed this is a problem that has come up several times. Should a GitHub issue be opened for it? If it’s of any use to know, it started happening with the adapter for CCX 2.16; I can confirm it’s not present in CCX 2.15. I have not tested the 2.19 adapter.
Other instances:
Note however, that the problem in the first thread you linked to is similar to this one but not the same. From what I understand, in that one a node was defined in CalculiX that was not part of the structural mesh but was defined as part of the interface and thus participated in the mapping. Since it was not part of the simulation it retained its original coordinates and messed up the mapping.
Regards
Andrés
Yes, please! 
And add as many details as you can so that we can reproduce / check it.
Thank you that seems to work!
Best Regards
Ramon
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