Meshing and running Problems

mintsa_icsd · April 27, 2011, 11:16

Hello,
I have some problems, i want to simulate a complete solar collector, but when meshing my geometry I got many cells with negative volume. How I can fix it?
secondly, when I run my simulation, I got an error '' reversed flow, and limited temperature in X cells''. Can you help me, please.

PS: I use StarCCM+ 6.02 and StarCCM+ 5.07

alastormoody11 · April 28, 2011, 01:02

Hi,

Regarding the meshing, have you checked whether your surface mesh is ok?

You can do this by going in representation, click on the initial mesh/remeshed surface depending on whether you are using the surface remesher and say repair surface. When you do so STAR will show you the problems with your surface mesh rectify them before creating your volume mesh. There might be a problem with pierced faces.

Regarding the solver problem, what you are specifying, is it an error or a warning? If it is a warning, you need not worry about it unless the warning persists over a large number of iterations. If it persists you would need to check your simulation setup to ensure that there are no mistakes.

abdul099 · April 28, 2011, 17:09

The reversed flow might be due to a pressure outlet boundary used as an inlet or due to a backflow through the pressure outlet. The fist one is o.k., the second one is suspicious and should be checked.
The temperature corrections are very suspicious, that shouldn't occur for more than a few iterations when convergence is good. If it persists, you should check your mesh quality. I assume, that could be the problem, because you got negative volume cells. That shouldn't be when meshing goes well.

April 27, 2011, 11:16	Meshing and running Problems	#1
mintsa_icsd New Member Mintsa Andre Join Date: Apr 2011 Posts: 3 Rep Power: 14	Hello, I have some problems, i want to simulate a complete solar collector, but when meshing my geometry I got many cells with negative volume. How I can fix it? secondly, when I run my simulation, I got an error '' reversed flow, and limited temperature in X cells''. Can you help me, please. PS: I use StarCCM+ 6.02 and StarCCM+ 5.07

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April 28, 2011, 01:02		#2
alastormoody11 Senior Member Join Date: Jun 2009 Posts: 100 Rep Power: 16	Hi, Regarding the meshing, have you checked whether your surface mesh is ok? You can do this by going in representation, click on the initial mesh/remeshed surface depending on whether you are using the surface remesher and say repair surface. When you do so STAR will show you the problems with your surface mesh rectify them before creating your volume mesh. There might be a problem with pierced faces. Regarding the solver problem, what you are specifying, is it an error or a warning? If it is a warning, you need not worry about it unless the warning persists over a large number of iterations. If it persists you would need to check your simulation setup to ensure that there are no mistakes.

April 28, 2011, 17:09		#3
abdul099 Senior Member Join Date: Oct 2009 Location: Germany Posts: 636 Rep Power: 21	The reversed flow might be due to a pressure outlet boundary used as an inlet or due to a backflow through the pressure outlet. The fist one is o.k., the second one is suspicious and should be checked. The temperature corrections are very suspicious, that shouldn't occur for more than a few iterations when convergence is good. If it persists, you should check your mesh quality. I assume, that could be the problem, because you got negative volume cells. That shouldn't be when meshing goes well.