[Commercial meshers] Star-CCM+ Mesh Parameters for OpenFOAM?

petr.f. · April 4, 2014, 09:44

Hi all,

I know that the following has already been discussed here, but it's been a while and maybe there is some new knowledge on this matter.

I'm using Star-CCM+ polyhedral mesh for two-phase computations in OpenFOAM (2.3.x). The geometry I'm meshing is quite complex - front end of a car including part of the underhood, hence I have to use the surface wrapper.

But no matter what meshing characteristics (base size, number of prism layers, face quality during surface remeshing, number of optimization cycles and threshold for polyhedral mesher) I use, the resulting mesh always contains some zero area and wrong oriented faces (polyhedral mesher produces the greatest amount, trimmer, which is basically snappyHex, a little bit less and tetrahedral mesher the smallest amount). StarCCM+ mesh analysis shows none of these problems, but checkMesh goes crazy (I use ccm26ToFoam for conversion)

I have removed all bad cells from the mesh using procedure described here http://openfoamwiki.net/index.php/SetSet (i.e. create set with bad cells, invert mesh, create subset) and replaced boundary condition on the newly created oldInternalFaces with "symmetry". However, OpenFOAM blows up right after the momentum predictor in the first iteration because of the floating point exception.

So, I'd be very glad if anyone could share his experience with any settings for StarCCM+ that ensure no negative volume cells, zero area faces or wrong oriented faces...

Thanks.

dreamilam · May 6, 2014, 00:31

Hi Petr,

I had similar problems with simpleFoam.

you can remove the zero area faces using the zero area faces indicator( split by function) in star CCM.
Negative volume cells can be removed by right clicking on the region and selecting the "Remove invalid cells" option (You might know this already).

I haven't tested it myself.
Pls give it a try and let me know if it works

Regards
ILAM

petr.f. · May 7, 2014, 07:09

Hi Ilam and thanks for the response. I know about these StarCCM+ tools, but unfortunately, they don't work perfectly. As for now, I haven't found any settings that would ensure the resulting mesh will be OK for OpenFOAM. The problem may be partially caused ccm26ToFoam as well... At the end I've decided switch to ANSA and snappyHexMesh.

April 4, 2014, 09:44	Star-CCM+ Mesh Parameters for OpenFOAM?	#1
petr.f. Member Petr Furmanek Join Date: Jan 2012 Location: Faenza, Italy Posts: 66 Rep Power: 14	Hi all, I know that the following has already been discussed here, but it's been a while and maybe there is some new knowledge on this matter. I'm using Star-CCM+ polyhedral mesh for two-phase computations in OpenFOAM (2.3.x). The geometry I'm meshing is quite complex - front end of a car including part of the underhood, hence I have to use the surface wrapper. But no matter what meshing characteristics (base size, number of prism layers, face quality during surface remeshing, number of optimization cycles and threshold for polyhedral mesher) I use, the resulting mesh always contains some zero area and wrong oriented faces (polyhedral mesher produces the greatest amount, trimmer, which is basically snappyHex, a little bit less and tetrahedral mesher the smallest amount). StarCCM+ mesh analysis shows none of these problems, but checkMesh goes crazy (I use ccm26ToFoam for conversion) I have removed all bad cells from the mesh using procedure described here http://openfoamwiki.net/index.php/SetSet (i.e. create set with bad cells, invert mesh, create subset) and replaced boundary condition on the newly created oldInternalFaces with "symmetry". However, OpenFOAM blows up right after the momentum predictor in the first iteration because of the floating point exception. So, I'd be very glad if anyone could share his experience with any settings for StarCCM+ that ensure no negative volume cells, zero area faces or wrong oriented faces... Thanks. Last edited by petr.f.; April 5, 2014 at 12:41.

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May 6, 2014, 00:31		#2
dreamilam New Member ILAM Join Date: May 2012 Location: chennai, INDIA Posts: 20 Rep Power: 13	Hi Petr, I had similar problems with simpleFoam. you can remove the zero area faces using the zero area faces indicator( split by function) in star CCM. Negative volume cells can be removed by right clicking on the region and selecting the "Remove invalid cells" option (You might know this already). I haven't tested it myself. Pls give it a try and let me know if it works Regards ILAM

May 7, 2014, 07:09		#3
petr.f. Member Petr Furmanek Join Date: Jan 2012 Location: Faenza, Italy Posts: 66 Rep Power: 14	Hi Ilam and thanks for the response. I know about these StarCCM+ tools, but unfortunately, they don't work perfectly. As for now, I haven't found any settings that would ensure the resulting mesh will be OK for OpenFOAM. The problem may be partially caused ccm26ToFoam as well... At the end I've decided switch to ANSA and snappyHexMesh.