Moving Meshes in CFX

robsta01 · February 11, 2011, 07:31

Hi

My problem is I need to simulate a flapping 2D flat plate in CFX. Therefore I need to be able to move the plate. I have only done stationary simulations before and do not know the best method to create this motion. I have thought of the possibility to allow the mesh to deform when the plate is moving but as my motion it quite great (30-35 degrees either side) I think the results I will get will be inaccurate.

Thanks for the help Rob

ghorrocks · February 12, 2011, 06:36

If the motion is a rotation (or even just oscillating rotation) do it with rotating frames of reference. If the motion is translation you can use GGI interfaces. If there is a complex motion you need moving mesh. Moving mesh is explained in the CFX tutorial examples.

If the motion is too great for moving mesh alone you can include a remeshing step.

robsta01 · February 12, 2011, 15:12

Yer is just rotation so I should hopefully be able to use rotating frames of reference. Do you know any specific tutorials which I'll find helpful?

Cheers Rob

ghorrocks · February 13, 2011, 06:58

No tutorials exist that I am aware of. There have been a number of posts on this topic on this forum, so do a search for them.

robsta01 · February 15, 2011, 07:43

If I have to put a hinge or multiple hinges on the plate to attempt to model a fish's motion will the rotating frames of reference technique work?

Thanks Rob

ghorrocks · February 15, 2011, 17:44

You cannot nest multiple frames of reference.

You would have to post a drawing of what you propose for a more considered answer.

robsta01 · February 16, 2011, 06:43

Hey I've attached a picture of a hinged aerofoil. My case is the same apart from I will be adding and varying the number hinges and I am simulating a flat plate not a foil. I wish to define the motion of each part of the plate such that I can simulate the motion of a fish. Would rotating frames of reference work in this case or is the motion too complex?

Cheers Robbie

ghorrocks · February 16, 2011, 17:06

You cannot nest rotating frames of reference.

You may be able to use one rotating frame of reference for the overall AOA, but the internal hinges will need to be done using moving mesh.

February 11, 2011, 07:31	Moving Meshes in CFX	#1
robsta01 New Member Join Date: Oct 2010 Posts: 4 Rep Power: 16	Hi My problem is I need to simulate a flapping 2D flat plate in CFX. Therefore I need to be able to move the plate. I have only done stationary simulations before and do not know the best method to create this motion. I have thought of the possibility to allow the mesh to deform when the plate is moving but as my motion it quite great (30-35 degrees either side) I think the results I will get will be inaccurate. Thanks for the help Rob

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February 12, 2011, 06:36		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	If the motion is a rotation (or even just oscillating rotation) do it with rotating frames of reference. If the motion is translation you can use GGI interfaces. If there is a complex motion you need moving mesh. Moving mesh is explained in the CFX tutorial examples. If the motion is too great for moving mesh alone you can include a remeshing step.

February 12, 2011, 15:12		#3
robsta01 New Member Join Date: Oct 2010 Posts: 4 Rep Power: 16	Yer is just rotation so I should hopefully be able to use rotating frames of reference. Do you know any specific tutorials which I'll find helpful? Cheers Rob

February 13, 2011, 06:58		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	No tutorials exist that I am aware of. There have been a number of posts on this topic on this forum, so do a search for them.

February 15, 2011, 07:43		#5
robsta01 New Member Join Date: Oct 2010 Posts: 4 Rep Power: 16	If I have to put a hinge or multiple hinges on the plate to attempt to model a fish's motion will the rotating frames of reference technique work? Thanks Rob

February 15, 2011, 17:44		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	You cannot nest multiple frames of reference. You would have to post a drawing of what you propose for a more considered answer.

February 16, 2011, 17:06		#8
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	You cannot nest rotating frames of reference. You may be able to use one rotating frame of reference for the overall AOA, but the internal hinges will need to be done using moving mesh.