anybody's done airfoil model with transition?

March 10, 2009, 04:58

It is a 2D simulation. The profile I used is NACA 0012. I used SST + transition (gamma theta) turbulence model. The residue cannot be converged under 1e-5. It just go periodically. Has anyone tried such kind of simulation before? Could you please give me some hints here?

March 10, 2009, 17:59

http://www.cfd-online.com/Wiki/Ansys...gence_criteria

In this case it is almost certainly transient motion of the turbulence transition point and/or laminar separation bubble. You will probably need to do a transient simulation to get good convergence.

Glenn Horrocks

March 10, 2009, 21:57

I am doing this for obtaining the lift and drag coefficients. When I do a transient simulation, these features oscilate much. How do you deal with it usually? Take an average? Cheers

March 11, 2009, 22:31

Hi,

What do you do in the wind tunnel? Run it for a while and record the force against time and average it to get the final result. CFD is just a numerical experiment so do the same thing.

Glenn Horrocks

March 10, 2009, 04:58	anybody's done airfoil model with transition?	#1
Hao Guest Posts: n/a	It is a 2D simulation. The profile I used is NACA 0012. I used SST + transition (gamma theta) turbulence model. The residue cannot be converged under 1e-5. It just go periodically. Has anyone tried such kind of simulation before? Could you please give me some hints here?

March 10, 2009, 17:59	Re: anybody's done airfoil model with transition?	#2
Glenn Horrocks Guest Posts: n/a	http://www.cfd-online.com/Wiki/Ansys...gence_criteria In this case it is almost certainly transient motion of the turbulence transition point and/or laminar separation bubble. You will probably need to do a transient simulation to get good convergence. Glenn Horrocks

March 10, 2009, 21:57	Re: anybody's done airfoil model with transition?	#3
Hao Guest Posts: n/a	I am doing this for obtaining the lift and drag coefficients. When I do a transient simulation, these features oscilate much. How do you deal with it usually? Take an average? Cheers

March 11, 2009, 22:31	Re: anybody's done airfoil model with transition?	#4
Glenn Horrocks Guest Posts: n/a	Hi, What do you do in the wind tunnel? Run it for a while and record the force against time and average it to get the final result. CFD is just a numerical experiment so do the same thing. Glenn Horrocks

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