question about boundary conditions

Nick R · February 20, 2011, 00:42

Hi all,

I'd like to simulate the flow over an infinite wing. For this purpose I created a rectangular domain and created part of the wing inside the domain. I have a problem setting the correct side walls (those that are parallel to the airfoil cross sections). If I set them as symmetry from what I understand it basically prevents spanwise flow normal to the sides walls which would not be realistic. Should I set them as periodic in order to simulate an infinite wing?
Please note that this is not a 2d problem.

I'd appreciate it, if you could give me the instructions in steps (I've never done a period BC (if this is what is needed). Thanks!

ghorrocks · February 21, 2011, 00:52

If you are expecting your infinite wing to generate 3D structures then you should do with periodic boundaries, with a distance between periodic boundaries at least as long as the biggest 3D structure you expect to see, and preferably several times that size.

Periodic boundaries are just a type of interface. Choose the interface type as periodic and the option as translational.

Nick R · February 21, 2011, 18:58

Thanks for the comments Glenn. I'll give it a try.

February 20, 2011, 00:42	question about boundary conditions	#1
Nick R Senior Member Nick Join Date: Nov 2010 Posts: 126 Rep Power: 15	Hi all, I'd like to simulate the flow over an infinite wing. For this purpose I created a rectangular domain and created part of the wing inside the domain. I have a problem setting the correct side walls (those that are parallel to the airfoil cross sections). If I set them as symmetry from what I understand it basically prevents spanwise flow normal to the sides walls which would not be realistic. Should I set them as periodic in order to simulate an infinite wing? Please note that this is not a 2d problem. I'd appreciate it, if you could give me the instructions in steps (I've never done a period BC (if this is what is needed). Thanks!

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February 21, 2011, 00:52		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,700 Rep Power: 143	If you are expecting your infinite wing to generate 3D structures then you should do with periodic boundaries, with a distance between periodic boundaries at least as long as the biggest 3D structure you expect to see, and preferably several times that size. Periodic boundaries are just a type of interface. Choose the interface type as periodic and the option as translational.

February 21, 2011, 18:58		#3
Nick R Senior Member Nick Join Date: Nov 2010 Posts: 126 Rep Power: 15	Thanks for the comments Glenn. I'll give it a try.