Obtaining Coefficient of Lift and Drag

Atella · February 12, 2010, 12:14

Hi,

I am investigating the performance of an aircraft wing and I need to find out the Coefficients of Lift and Drag for the wing.

I am able to run a simulation and obtain the contour and vector plots but I am unable to find if there is a part to CFX which will give me a value for the Cl of Cd.

If anyone would know how i could get this out it would be much appreciated.

Thanks

ghorrocks · February 13, 2010, 06:01

I must have answered this question a dozen times. I really should write a wiki on it....

Extract the forces off the airfoil either from the output file or from CFD-Post. Then stick the other values in (density, free stream velocity) and use the definition of CD and CL to get the lift and drag coefficients.

If you want to you can write a CEL expression to calculate this as the simulation progresses, Then you can output it to a monitor point and then you can use CL and CD to help inform your decision as to whether the simulation has converged.

February 12, 2010, 12:14	Obtaining Coefficient of Lift and Drag	#1
Atella New Member Join Date: Jan 2010 Posts: 8 Rep Power: 16	Hi, I am investigating the performance of an aircraft wing and I need to find out the Coefficients of Lift and Drag for the wing. I am able to run a simulation and obtain the contour and vector plots but I am unable to find if there is a part to CFX which will give me a value for the Cl of Cd. If anyone would know how i could get this out it would be much appreciated. Thanks

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February 13, 2010, 06:01		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	I must have answered this question a dozen times. I really should write a wiki on it.... Extract the forces off the airfoil either from the output file or from CFD-Post. Then stick the other values in (density, free stream velocity) and use the definition of CD and CL to get the lift and drag coefficients. If you want to you can write a CEL expression to calculate this as the simulation progresses, Then you can output it to a monitor point and then you can use CL and CD to help inform your decision as to whether the simulation has converged.