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Old   May 23, 2013, 08:40
Unhappy fluent boundary conditions
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Ashish Kumar
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I am using fluent for the first time and I am simulating naca 0012 airfoil under invscid conditions. But I am getting negative values for drag coefficient for angle of attacks around 6-10 degrees. I am using boundary conditions of velocity inlet, pressure outlet and symmetry. Is there any problem in my boundary conditions. My drag direction vector is right pointing towards trailing edge from leading edge.
What is the problem, I am unable to identify.
Please help me..
Thanks in advance..
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Old   May 23, 2013, 13:08
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Ghazlani M. Ali
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try far-field as inlet...
New to ICEM CFD, try this document -->
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Old   May 24, 2013, 09:05
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Try to change the size mesh, time step and relaxation factors
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Old   May 27, 2013, 04:52
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Muhammad Aqib Chishty
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What is the value of your velocity?
Recheck your boundary conditions and your case setup from start.
Your case is incompressible or compressible check this too because if flow is compressible then you have to used the Density Based Solver and then turbulence modeling will play the role.

Best of luck!!!
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Old   February 4, 2014, 06:44
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Nick Prendergast
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I'm having a similar problem with the same aerofoil, do you remember if you got the drag coefficient to become positive and if so, how?

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Old   February 6, 2014, 20:42
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It may have been his drag definition. Drag is defined relative to the freestream, not the airfoil direction.
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boundary conditions, naca 0012, velocity inlet face

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