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December 23, 2013, 13:09
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airfoil with negative drag
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#1 |
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New Member
Join Date: Dec 2013
Posts: 3
Rep Power: 13  |
Hi,
I have simulated a 2D rear wing with two airfoils. The drag coefficient of the large airfoil is negative, the drag of the smaller one is positive. In my view this is not possible. I use a structural mesh and the k-e-model. Can someone help me? |
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December 23, 2013, 13:15
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#2 |
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Super Moderator
Alex
Join Date: Jun 2012
Location: Germany
Posts: 3,428
Rep Power: 49 |
Please take a look at the FAQ before inventing a self-propelling airfoil
http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F |
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December 28, 2013, 06:54
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#3 |
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New Member
Join Date: Dec 2013
Posts: 3
Rep Power: 13 |
I have calculated the rear wing with different turbulence models, structured (fine and coarse) and unstructured mesh, 2D and 3D models. The y+ value is between 30 and 300. The pressure portion of the drag is always negative, the viscous portion is positive.
I have also replaced the larger profile with an ellipse body. In this case the drag coefficient is positive… |
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| Tags |
| airfoil2d, negative drag |
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