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-   -   Drag Coeffient monitor very high (http://www.cfd-online.com/Forums/star-ccm/109968-drag-coeffient-monitor-very-high.html)

dwilson December 1, 2012 17:09

Drag Coeffient monitor very high
 
I am modeling a NACA 0012 in 2D. I have drawn the aerofoil and the freestream box in NX and imported the CAD in. I then set everything up and I have set up two monitors for Cl and Cd in order to compare them to experimental data.

The Cl I have is around 1.2 which is a little high but the Cd i have is -3 and should be around 0.2. I have no idea why this is. I have set the reference values correctly I think in the monitor section (1.177 for density ref pressure is 101325 velocity is 6.943 force option is pressure +shear and the direction is set to components 0.9848,0.1736,0 as the aerofoil is simulated to be at 10 degrees. I have been looking for ages as to why the drag might be so high as I cant see anything wrong.

any throughts?

nomad December 4, 2012 22:14

You should resolve forces in the streamwise(drag) and normal(lift) directions since your freestream is at an alpha.

niazaliahmed December 21, 2012 05:56

Hi try choosing Standard K-Epsilon Low Re with adequate mesh resolution near the wall...


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