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Heat exchanger, failed to evaluate variable
Posted 21 mars 2011, 10:09 UTC−4 Fluid & Heat, Heat Transfer & Phase Change 2 Replies
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I'm trying to model two counterflowing fluids (water and steam), which exchange heat through a copper surface. I'm using General Heat Transfer and Incompressible Navier-Stokes modules.
I've set up inlets and outlets in the N-S module and constant temperatures and convective fluxes in the heat transfer module. I've been messing with many settings and I may be close to solution, but now I'm getting the error:
Failed to evaluate variable U_ns
Geometry 1
Dimension 2
Domains{2}
I can't figure out what that variable is and how I could fix it. In Physics->Equation systems->Subdomain Settings I found a list of variables that has U_chns, but not U_ns. Even if it was there I wouldn't know what to do. Any ideas? I've attached the file (from COMSOL 3.4).
I've set up inlets and outlets in the N-S module and constant temperatures and convective fluxes in the heat transfer module. I've been messing with many settings and I may be close to solution, but now I'm getting the error:
Failed to evaluate variable U_ns
Geometry 1
Dimension 2
Domains{2}
I can't figure out what that variable is and how I could fix it. In Physics->Equation systems->Subdomain Settings I found a list of variables that has U_chns, but not U_ns. Even if it was there I wouldn't know what to do. Any ideas? I've attached the file (from COMSOL 3.4).
Attachments:
2 Replies Last Post 22 mars 2011, 09:49 UTC−4
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Posted:
1 decade ago
Hi
3.5 is too old for my versions, but is you are in "chns" and get a variable name of "ns", there must be something messed up. You should either check the underlaying equations or redo your model from fresh
--
Good luck
Ivar
3.5 is too old for my versions, but is you are in "chns" and get a variable name of "ns", there must be something messed up. You should either check the underlaying equations or redo your model from fresh
--
Good luck
Ivar
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Posted:
1 decade ago
Alright. I rebuilt the model and still got singular matrix errors like before. I finally managed to get a solution when I inserted better initial values for temperature. Still don't understand what that weird constant was, but now it's working. Thanks.