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October 31, 2017, 14:18 |
Energy equation blows up in simple channel
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#1 |
Senior Member
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Hello experts,
I am solving a channel flow with conjugate heat transfer. So it has solid regions apart from fluid domains. This problem never occurred to me before. And I tried my best to solve it but no clue. I am doing simulation of water through this channel which is convex in the middle of its axial length. The walls are made of copper. I simulate the flow very well with all equations converged below to 1e-06. But when I turn on energy , the residual goes to 1e14 (in simple terms, it diverges). I tried coupled, simple, coupled with pseudo transient etc. but did not find a solution. MEsh is ok as well. I am totally stuck. Why the solution is diverging? The temperature is room temperature 300K and no heat source. But I need to turn energy on because later I have to solve CHT problem by giving flux at the bottom of channel. Please help |
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November 1, 2017, 11:26 |
Better shell concuction instead of solid mesh?
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#2 |
Senior Member
Moritz Kuhn
Join Date: Apr 2010
Location: Germany, Dresden
Posts: 207
Rep Power: 17 |
Hello Shamoon,
It is possible that your solid mesh is not properly connected with the fluid mesh? Try to solve your problem without the solid mesh and use for your channel wall a defined wall thickness in conjunction with "shell conduction" instead. Moritz |
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November 1, 2017, 12:03 |
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#3 |
Super Moderator
Alex
Join Date: Jun 2012
Location: Germany
Posts: 3,400
Rep Power: 47 |
You could try to make a sketch with all the boundary conditions, material properties and initial values you used and upload it here. That might give us a hint if there is a problem with the setup.
When you say "turn on energy equation": do did you remember to initialize the temperature with a reasonable value before proceeding with the calculation? |
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November 1, 2017, 12:31 |
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#4 |
Senior Member
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Actually, I believe that shell conduction does not work. I tried it many times for simple pipe flows, but it does not give correct results.
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November 1, 2017, 12:45 |
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#5 | |
Senior Member
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Quote:
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November 2, 2017, 08:44 |
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#6 | |
Senior Member
Moritz Kuhn
Join Date: Apr 2010
Location: Germany, Dresden
Posts: 207
Rep Power: 17 |
Quote:
Try to locate the error after some iterations, maybe you have some local very high (respectively low) temperatures, this could indicate poor mesh at this location. |
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