Patch Conform or Independent

Torque_Converter · May 10, 2012, 15:09

Hi All,

Is there any danger in using a patch independent mesh other than losing fidelity in your geometry?

Patch Independent seems to keep every detail of my geometry, plus appears to be rather well structured compared to patch conforming. I imagine this would be good for speed of computation.

Is there any danger in this reporting wrong answers due to some complication?

Thanks

ghorrocks · May 10, 2012, 23:52

All meshers, when properly used, can conform to a surface. Of course the whole point of meshing is to loose fidelity, the issue is to keep the loss to an acceptable amount.

So both the patch independant and patch conforming methods, when correctly used, can generate good meshes. Use the mesh quality metrics to assess the quality of the mesh.

Torque_Converter · May 11, 2012, 08:20

Thanks. This indicates I need to look elsewhere for the phenomena I'm seeing. Basically the turbulence and mass/momentum are converging, but via constantly fluctuating convergence. It basically looks like a sine wave that is heading downward. Would this likely be mesh not being fine enough? Or a sign of strong transient behaviour.

Edit: It seems to smooth out somewhat with time scale an order or two of magnitude less.

ghorrocks · May 13, 2012, 07:08

Your question now is covered by an FAQ:

http://www.cfd-online.com/Wiki/Ansys...gence_criteria

May 10, 2012, 15:09	Patch Conform or Independent	#1
Torque_Converter Member Join Date: Jan 2012 Location: Edmonton, CA Posts: 87 Rep Power: 14	Hi All, Is there any danger in using a patch independent mesh other than losing fidelity in your geometry? Patch Independent seems to keep every detail of my geometry, plus appears to be rather well structured compared to patch conforming. I imagine this would be good for speed of computation. Is there any danger in this reporting wrong answers due to some complication? Thanks

May 10, 2012, 23:52		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,697 Rep Power: 143	All meshers, when properly used, can conform to a surface. Of course the whole point of meshing is to loose fidelity, the issue is to keep the loss to an acceptable amount. So both the patch independant and patch conforming methods, when correctly used, can generate good meshes. Use the mesh quality metrics to assess the quality of the mesh. Far and pradyun like this.

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May 11, 2012, 08:20		#3
Torque_Converter Member Join Date: Jan 2012 Location: Edmonton, CA Posts: 87 Rep Power: 14	Thanks. This indicates I need to look elsewhere for the phenomena I'm seeing. Basically the turbulence and mass/momentum are converging, but via constantly fluctuating convergence. It basically looks like a sine wave that is heading downward. Would this likely be mesh not being fine enough? Or a sign of strong transient behaviour. Edit: It seems to smooth out somewhat with time scale an order or two of magnitude less.

May 13, 2012, 07:08		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,697 Rep Power: 143	Your question now is covered by an FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria