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ashishtbm May 23, 2013 07:40

fluent boundary conditions
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..

diamondx May 23, 2013 12:08

try far-field as inlet...

jziha May 24, 2013 08:05

Try to change the size mesh, time step and relaxation factors

MAC88 May 27, 2013 03:52

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!!!

neprendo February 4, 2014 06:44

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? :)


me3840 February 6, 2014 20:42

It may have been his drag definition. Drag is defined relative to the freestream, not the airfoil direction.

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