CFD validation case，Help！

adam_annie · February 8, 2010, 14:24

hello everyone, did anybody have an experience on the CFD validation case in NPARC, like RAE2822 airfoil and M6 wing. I have difficult in simulate the RAE2822 case even though I use the same grids as the test case used. I used CFX and Fluent software, but the result is too bad. So can anyone help me and give me some advice about how to set the boundary condition or other problem. Thank you very much.

Ahmed · February 8, 2010, 18:19

Are you referring to this case http://www.grc.nasa.gov/WWW/wind/val...af/raetaf.html
It is a classical case, inlet, top, bottom are far field bc,

adam_annie · February 9, 2010, 17:52

Thanks, the nets I have already know, in CFX it has not FARFIELD boundary condition, so what condition is proper? Opening or Inlet and Outlet, I am not very sure. Or whatever condition, the key point is setting free stream condition in the farfield and average 0 pressure in the outlet? Am i right? Thanks a lot

Ahmed · February 9, 2010, 21:04

The far field BC in Fluent parlance is the classical plenuum BC (flow variables do not change with respect to time) In the CFX parlance I think it is called reservoir (not sure, it has been a long time )
The outlet is just outlet BC where the gradients of the flow variables are Zero by definition, i.e, a smart way of extrapolating the flow variables to the outlet itself
Good Luck

February 8, 2010, 14:24	CFD validation case，Help！	#1
adam_annie New Member Yibin Dou Join Date: Dec 2009 Posts: 13 Rep Power: 16	hello everyone, did anybody have an experience on the CFD validation case in NPARC, like RAE2822 airfoil and M6 wing. I have difficult in simulate the RAE2822 case even though I use the same grids as the test case used. I used CFX and Fluent software, but the result is too bad. So can anyone help me and give me some advice about how to set the boundary condition or other problem. Thank you very much.

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February 8, 2010, 18:19		#2
Ahmed Senior Member Ahmed Join Date: Mar 2009 Location: NY Posts: 251 Rep Power: 18	Are you referring to this case http://www.grc.nasa.gov/WWW/wind/val...af/raetaf.html It is a classical case, inlet, top, bottom are far field bc,

February 9, 2010, 17:52		#3
adam_annie New Member Yibin Dou Join Date: Dec 2009 Posts: 13 Rep Power: 16	Thanks, the nets I have already know, in CFX it has not FARFIELD boundary condition, so what condition is proper? Opening or Inlet and Outlet, I am not very sure. Or whatever condition, the key point is setting free stream condition in the farfield and average 0 pressure in the outlet? Am i right? Thanks a lot

February 9, 2010, 21:04		#4
Ahmed Senior Member Ahmed Join Date: Mar 2009 Location: NY Posts: 251 Rep Power: 18	The far field BC in Fluent parlance is the classical plenuum BC (flow variables do not change with respect to time) In the CFX parlance I think it is called reservoir (not sure, it has been a long time ) The outlet is just outlet BC where the gradients of the flow variables are Zero by definition, i.e, a smart way of extrapolating the flow variables to the outlet itself Good Luck