Overset mesh

jcamilleri · March 18, 2014, 11:28

Hi all,

I've been trying to model wedge impact using Star CCM overset mesh. I have no problems when modelling the whole wedge however, when I try to model half the wedge I get this error message:

Found acceptors with zero donors in overset

I followed the life boat tutorial with regards to settings and I tried all sorts of combinations (fine background coarse overset, fine/fine, coarse/fine etc...) Could it be because of the symmetry plane I am using? Any ideas?

Thank you.

lava12005 · March 19, 2014, 03:41

Maybe your background mesh is significantly finer than the overset mesh?
Make sure they are of the same size.

Sym plane should not be the issue.

ping · March 22, 2014, 04:27

use the overset representation and field functions to visualise where the problem occurs. it could also be a time step issue with the mesh traveling too far

jcamilleri · March 22, 2014, 05:18

Hi all,

Thank you for your reply.

Lava, I used an overlap region over which the overset mesh is located. They have the same cell size. Could it be because, the overset mesh requires 4-5 cells around it and on the symmetry plane this is not provided?

Ping, I did not run the simulation. Once I generate the mesh, I initialize the solution to check the mesh and get this error. Should I set up the whole simulation and run it to see what happens?

Josef

ping · March 24, 2014, 05:29

i imagine you need to read the rules for creating an overset mesh and the carefully examine your geometry and mesh to ensure all rules are met - it is really very easy if you follow the rules

lava12005 · March 24, 2014, 21:07

Yes, I am not sure on how your problem is, maybe you can give some picture?
The region which is moving (the one you applied Overset Mesh BC) needs to have Symmetry BC as well at the Symmetry plane.. There won't be 4-5 cells around it for sure but it is fine.

March 18, 2014, 11:28	Overset mesh	#1
jcamilleri New Member Josef Camilleri Join Date: Mar 2014 Posts: 27 Rep Power: 12	Hi all, I've been trying to model wedge impact using Star CCM overset mesh. I have no problems when modelling the whole wedge however, when I try to model half the wedge I get this error message: Found acceptors with zero donors in overset I followed the life boat tutorial with regards to settings and I tried all sorts of combinations (fine background coarse overset, fine/fine, coarse/fine etc...) Could it be because of the symmetry plane I am using? Any ideas? Thank you.

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March 19, 2014, 03:41		#2
lava12005 Senior Member KHB Join Date: Aug 2010 Location: Singapore Posts: 118 Rep Power: 16	Maybe your background mesh is significantly finer than the overset mesh? Make sure they are of the same size. Sym plane should not be the issue.

March 22, 2014, 04:27		#3
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	use the overset representation and field functions to visualise where the problem occurs. it could also be a time step issue with the mesh traveling too far

March 22, 2014, 05:18		#4
jcamilleri New Member Josef Camilleri Join Date: Mar 2014 Posts: 27 Rep Power: 12	Hi all, Thank you for your reply. Lava, I used an overlap region over which the overset mesh is located. They have the same cell size. Could it be because, the overset mesh requires 4-5 cells around it and on the symmetry plane this is not provided? Ping, I did not run the simulation. Once I generate the mesh, I initialize the solution to check the mesh and get this error. Should I set up the whole simulation and run it to see what happens? Josef

March 24, 2014, 05:29		#5
ping Senior Member Ping Join Date: Mar 2009 Posts: 556 Rep Power: 20	i imagine you need to read the rules for creating an overset mesh and the carefully examine your geometry and mesh to ensure all rules are met - it is really very easy if you follow the rules

March 24, 2014, 21:07		#6
lava12005 Senior Member KHB Join Date: Aug 2010 Location: Singapore Posts: 118 Rep Power: 16	Yes, I am not sure on how your problem is, maybe you can give some picture? The region which is moving (the one you applied Overset Mesh BC) needs to have Symmetry BC as well at the Symmetry plane.. There won't be 4-5 cells around it for sure but it is fine.