Multi region meshing

noob@cfd · March 16, 2012, 03:18

Hi everyone,

I have been wanting to use the import wings toolbox. The bounding box created by the mesher is not big enough for its boundaries to be set with boundary conditions. Another region has to be created which encompasses the bounding box. I have been told to fill this region up with polyhedral cells. However, I am not able to make out how carry out the meshing on the outer box, as in

Do I mesh the second region separately and then combine the region with an interface? When I do that I get totally wrong results. Also get a warning no intersection found.

Or should I merge the regions first and then do the meshing?

Please help me out.

Regards

Jimmy123 · March 20, 2012, 05:45

Hello, I'm also a noob but I'm working on a similar problem right now. So correct me if I'm wrong because I need every help I can get. I would say that you first need to get the regions separated by an interface. One way of doing this is to first combine your part with the bounding part into one, and then use split by surface topology. Then the interface will appear when you assign the parts to different regions. In order to get a conformal mesh between the two regions you use one mesh continuum for both regions. And I think that it is only polyhedral and tetrahedral meshes that can produce a conformal mesh. But if you are using StarCCM 7.02 I have heard that you can use some kind of mapped interface and hence use different meshes.
Hope this helped you!
Good luck /Jimmy

DanHamilton · March 26, 2012, 13:32

It's pretty important that you spend the time up front to understand how interfaces work in STAR-CCM+ - it'll save you loads of hair-pulling in the future. You need to get all of your interfaces set up before you mesh - the easiest way to do this is through use of the boolean operations at part or region level. I'd recommend looking through the vast tutorial docs.

You can have different mesh continua for your different regions. It generally doesn't matter if the interface is conformal - if your face sizes on either side are similar, you'll get a good interface. The new direct map interfaces in 7.02 are currently only valid for fluid/solid interfaces.

Regards
Dan

March 16, 2012, 03:18	Multi region meshing	#1
noob@cfd New Member Join Date: Mar 2012 Posts: 1 Rep Power: 0	Hi everyone, I have been wanting to use the import wings toolbox. The bounding box created by the mesher is not big enough for its boundaries to be set with boundary conditions. Another region has to be created which encompasses the bounding box. I have been told to fill this region up with polyhedral cells. However, I am not able to make out how carry out the meshing on the outer box, as in Do I mesh the second region separately and then combine the region with an interface? When I do that I get totally wrong results. Also get a warning no intersection found. Or should I merge the regions first and then do the meshing? Please help me out. Regards

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March 20, 2012, 05:45		#2
Jimmy123 New Member Jimmy Join Date: Apr 2011 Posts: 12 Rep Power: 15	Hello, I'm also a noob but I'm working on a similar problem right now. So correct me if I'm wrong because I need every help I can get. I would say that you first need to get the regions separated by an interface. One way of doing this is to first combine your part with the bounding part into one, and then use split by surface topology. Then the interface will appear when you assign the parts to different regions. In order to get a conformal mesh between the two regions you use one mesh continuum for both regions. And I think that it is only polyhedral and tetrahedral meshes that can produce a conformal mesh. But if you are using StarCCM 7.02 I have heard that you can use some kind of mapped interface and hence use different meshes. Hope this helped you! Good luck /Jimmy

March 26, 2012, 13:32		#3
DanHamilton New Member Dan Hamilton Join Date: Mar 2012 Posts: 7 Rep Power: 14	It's pretty important that you spend the time up front to understand how interfaces work in STAR-CCM+ - it'll save you loads of hair-pulling in the future. You need to get all of your interfaces set up before you mesh - the easiest way to do this is through use of the boolean operations at part or region level. I'd recommend looking through the vast tutorial docs. You can have different mesh continua for your different regions. It generally doesn't matter if the interface is conformal - if your face sizes on either side are similar, you'll get a good interface. The new direct map interfaces in 7.02 are currently only valid for fluid/solid interfaces. Regards Dan