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high drag Coefficient 2D airfoil

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Old   February 13, 2017, 08:21
Default high drag Coefficient 2D airfoil
bye bye my blue
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bye bye my blue is an unknown quantity at this point
I'm simulating 2D airfoil..

Governing eqn is kEpsilon

y+ min : 6.96 max = 30.79859 average = 15.6028

and mesh is generated by salome (viscous layer =0.03 and distance:0.0006)

at (, i used 0.0006

xfoil naca0015 Cd = 0.00579 and mine is 0.048

I don't know what is the problem..

here are mesh picture and 0,system,postprocess folders

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File Type: jpg 20170213_211939.jpg (86.6 KB, 19 views)
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File Type: gz 0,system,postprocess.tar.gz (150.1 KB, 3 views)
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Old   February 15, 2017, 09:57
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Drag prediction is strongly dependant on the resolution of the viscous layer. K-epsilon model uses wall-function to model this region (30<y+ <300) and drag is not correctly predicted.

I suggest you to use Spalart Allmaras or SST k-omega models with a y+~1 in order to obtain more realistic values.

Also, check the dimensions of the mesh. Maybe your domain is too small and the wake is not fully captured (or mesh resolution is not enough in this region)
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