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Naca airfoil with to much drag

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Old   March 15, 2006, 11:26
Default Naca airfoil with to much drag
  #1
Andreas
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Hi!

I try to calculate a flow around some Naca 4 digit airfoils. In my calculation the lift is nearly right, but the drag is much too high. I'm comparing the calculated values with the book "theory of wing sections". Can you give me a reason or advice? I use a wall as boundary condition for a profil and the calculations are done with the standard k-epsilon turbulence model.

Thank you Andreas
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Old   March 15, 2006, 11:41
Default Re: Naca airfoil with to much drag
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ms
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The K-E is probably your problem. they are not ideally suited for these kind of flows. An SST model would prob give you better results.

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Old   March 15, 2006, 11:53
Default Re: Naca airfoil with to much drag
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Andreas
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Hi!

I tried this too, because I had the same idea but the results are nearly equal. So I don't know what I'm doing wrong.

Andreas
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Old   March 15, 2006, 13:22
Default Re: Naca airfoil with to much drag
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Ogbeni
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What advection scheme are you using ? Try specified Blend or High Res.
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Old   March 15, 2006, 13:43
Default Re: Naca airfoil with to much drag
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vijesh joshi
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what scheme you are using? because if you are trying for some supersonic / hypersonic case, then use upwind scheme. other thing is use local time scale factor<1.
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Old   March 15, 2006, 13:52
Default Re: Naca airfoil with to much drag
  #6
PetrK
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Check this forum, there are a lot of topics with this problem. You need very fine mesh, y+ bellow 2, run as transident, SST turbulence model with transition model, high resolution advection scheme.

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Old   March 17, 2006, 07:13
Default Re: Naca airfoil with to much drag
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AndiMb
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Hi!

Thanks for your help. It worked. Sorry, that I didn't search in the post.

Andreas
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