Rigid body solution or Immersed solid

omidiut · July 3, 2012, 01:59

Hi all
I'm trying to simulate movement of a L shape in a compressible flow at Ma=0.8.
Its have a 3 degree of freedom( X & Y translation and Z rotation). I like to know what is the different of simluate it by rigid body solution(beta features) or Immersed solid?

Due to large displacement of the body, negative volume occurred, is there any way to solve this problem without remeshing?

Best regards.

ghorrocks · July 3, 2012, 02:36

Immersed solids do not support heat transfer. That means you cannot use them in compressible flow - that's my reading of the limitations of immersed solids, please correct e if I am wrong.

So your only option is using a rigid body and moving mesh. If you have 3 DOF you might be able to make the region around the body have the mesh move with the body, and the motion be done as compression/expansion of mesh around the body. Usually the negative volumes occur near the body as the mesh distorts around the body so this owuld move the mesh motion away from the body and simplify it so you have a better chance to avoid mesh folding.

Alternately you might be able to achieve a similar thing using a mesh smoothing weighting factor which weights the mesh near the body and fades away slowly away from it. This would be much easier to implement but it is not always successful.

July 3, 2012, 01:59	Rigid body solution or Immersed solid	#1
omidiut Senior Member omid Join Date: Apr 2011 Posts: 105 Rep Power: 14	Hi all I'm trying to simulate movement of a L shape in a compressible flow at Ma=0.8. Its have a 3 degree of freedom( X & Y translation and Z rotation). I like to know what is the different of simluate it by rigid body solution(beta features) or Immersed solid? Due to large displacement of the body, negative volume occurred, is there any way to solve this problem without remeshing? Best regards.

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July 3, 2012, 02:36		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	Immersed solids do not support heat transfer. That means you cannot use them in compressible flow - that's my reading of the limitations of immersed solids, please correct e if I am wrong. So your only option is using a rigid body and moving mesh. If you have 3 DOF you might be able to make the region around the body have the mesh move with the body, and the motion be done as compression/expansion of mesh around the body. Usually the negative volumes occur near the body as the mesh distorts around the body so this owuld move the mesh motion away from the body and simplify it so you have a better chance to avoid mesh folding. Alternately you might be able to achieve a similar thing using a mesh smoothing weighting factor which weights the mesh near the body and fades away slowly away from it. This would be much easier to implement but it is not always successful.