# Simple Question Regarding Symmetry Planes

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 April 9, 2010, 10:59 Simple Question Regarding Symmetry Planes #1 New Member   Join Date: Jan 2010 Posts: 8 Rep Power: 16 Hi, Simple question i hope... I am looking at the flow around an airfoil and i used a symmetry plane down the centre of the wing in order to reduce computational time. When it comes to working out the CL of the wing i obtain my z-force using CFX and using CL=L/0.5*rho*v^2*A calculate CL. My question is what is the area is use? I know it has to be the planform area however as i used a symmetry plane is the area now HALF as the symmetry plane cuts the wing in half, or has the CFD taken this into account and the area is the full plan area. Thanks

 April 10, 2010, 06:40 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 Symmetry planes have no effect on volume or surface integrals, or global balances or flow rates either for that matter. So if you use the area()@ function it will just be the area of the meshed region, and the force()@ function will just return the force of the meshed region.

 April 10, 2010, 08:43 #3 New Member   Join Date: Jan 2010 Posts: 8 Rep Power: 16 Thanks for that, so to work out the force on the whole wing is it 2x the area of the meshed region, considering the meshed region is half a wing. Cheers

 April 11, 2010, 06:44 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,819 Rep Power: 144 Yes, you would have to double the force reported.