Appropriate mesh for LES

jitahz · October 19, 2010, 08:01

Hi,

i am wondering if any one can help me or send me some references fon appropriate mesh for LES!

Thanks and Regards

Jade M · October 19, 2010, 10:39

CFX's Solver Modeling Guide states the following

"The mesh and timesteps are an inherent part of the model. LES models make use of the grid scale for filtering out the turbulence. If the mesh is anisotropic to resolve a jet, for example, the longer length scale in the flow direction may also have an undue effect on the cross-stream turbulence. For this reason, consider the use of isotropic grids, perhaps using tetrahedral rather than hexahedral elements."

"If the boundary layer structure is important, you should resolve it with at least 15 points across the boundary layer and with the first grid point at a position of approximately y+ = 1. Note however, that large aspect rations in the mesh are not suitable for LES. This often results in excessive resolution requirements for boundary layer flows."

I was hoping that there would be references but I did not see any. Perhaps these couple of paragraphs will help. Good luck!

October 19, 2010, 08:01	Appropriate mesh for LES	#1
jitahz New Member Join Date: Oct 2010 Posts: 1 Rep Power: 0	Hi, i am wondering if any one can help me or send me some references fon appropriate mesh for LES! Thanks and Regards

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October 19, 2010, 10:39		#2
Jade M Senior Member Join Date: Feb 2010 Posts: 148 Rep Power: 17	CFX's Solver Modeling Guide states the following "The mesh and timesteps are an inherent part of the model. LES models make use of the grid scale for filtering out the turbulence. If the mesh is anisotropic to resolve a jet, for example, the longer length scale in the flow direction may also have an undue effect on the cross-stream turbulence. For this reason, consider the use of isotropic grids, perhaps using tetrahedral rather than hexahedral elements." "If the boundary layer structure is important, you should resolve it with at least 15 points across the boundary layer and with the first grid point at a position of approximately y+ = 1. Note however, that large aspect rations in the mesh are not suitable for LES. This often results in excessive resolution requirements for boundary layer flows." I was hoping that there would be references but I did not see any. Perhaps these couple of paragraphs will help. Good luck!