Stability problems with kepsilon in external aero

ryan_m · June 11, 2008, 20:46

Hey guys,

I have recently run a heap of 3D airfoils and have got some good results. I turn the turbulence off for around 400 iterations, and after that k and epsilon converge nicely. I think I have narrowed my error down to the "transformPoints" function in OpenFOAM. I was originally creating meshes in GAMBIT in mm, then converting this to FOAM and then scaling the mesh down to metres using:

transformPoints <root> <case> -scale "(0.001 0.001 0.001)"

Doing this gave poor results. What I did in the past couple of runs was to create the mesh in GAMBIT in metres, therefore I didnt need to use transformPoints in FOAM. Doing this I have got excellent conergence with both incompressible and compressible solvers. I am getting drag coefficients between 0.01-0.02 for my airfoils, which is very reasonable.

Dont know if this will help any of you, but thought I would post it.

Cheers,
Ryan

pcasto · July 16, 2008, 16:00

Hi Ryan,

I'm also interested in simulating the flow over wings. Do you think you could post one of your case or send it by email. It would be really useful.

Thank you

Patrice

June 11, 2008, 20:46	Hey guys, I have recently r	#21
ryan_m New Member Ryan Middleton Join Date: Mar 2009 Posts: 17 Rep Power: 17	Hey guys, I have recently run a heap of 3D airfoils and have got some good results. I turn the turbulence off for around 400 iterations, and after that k and epsilon converge nicely. I think I have narrowed my error down to the "transformPoints" function in OpenFOAM. I was originally creating meshes in GAMBIT in mm, then converting this to FOAM and then scaling the mesh down to metres using: transformPoints <root> <case> -scale "(0.001 0.001 0.001)" Doing this gave poor results. What I did in the past couple of runs was to create the mesh in GAMBIT in metres, therefore I didnt need to use transformPoints in FOAM. Doing this I have got excellent conergence with both incompressible and compressible solvers. I am getting drag coefficients between 0.01-0.02 for my airfoils, which is very reasonable. Dont know if this will help any of you, but thought I would post it. Cheers, Ryan

July 16, 2008, 16:00	Hi Ryan, I'm also intereste	#22
pcasto New Member Patrice Castonguay Join Date: Mar 2009 Posts: 7 Rep Power: 17	Hi Ryan, I'm also interested in simulating the flow over wings. Do you think you could post one of your case or send it by email. It would be really useful. Thank you Patrice

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