[mihylee]

Hi,

I am trying to test NACA airfoil which has Re=3x10^6 in Fluent.

First, I tested with SST K-omega (turbulent model) and compared the results with experimental data. The Cl value was very similar (under 3% error) but the Cd value was around error of 37%.

I read one article ("Evaluation of the turbulence models for the simulation
of the flow over a National Advisory Committee for
Aeronautics (NACA) 0012 airfoil" byDouvi C. Eleni*, Tsavalos I. Athanasios and Margaris P. Dionissios) says if I split the domain into laminar and turbulent regions, I can get much accurate results.

However, I have no idea how to split the domain into two regions.
If I assume like below picture but we can select only one model like I choose SST k-omega.
Is there anyway I can specify two models, one for laminar and turbulent?
https://ibb.co/BsKrYDt

[LuckyTran]

Select your turbulence model in the viscous model.

You need two cell zones. One for the laminar and one for the turbulent. Then go to cell zone conditions and specify that region as a laminar zone.

[mihylee]

Thank you, LuckyTran.
I will try that

[mihylee]

Originally Posted by LuckyTran

Select your turbulence model in the viscous model.

You need two cell zones. One for the laminar and one for the turbulent. Then go to cell zone conditions and specify that region as a laminar zone.

Hi LuckyTran,

I managed to separate the flow zone into laminar and turbulent.

It did decrease my drag coefficient value a lot.
However, my lift and drag values were started to fluctuate from 8 degrees AOA and so on.

I don't know why it happened.
Is it because I did not predict transition point correctly? (maybe turbulent zone is larger and it created large wake which caused fluctuating values?)

Please help.

[sidharth13]

hello Mihylee,

Am also facing the same problem. the values of lift and drag coefficients are fluctuating at an angle of 9 degree. i tried changing the transition points on the both surfaces of an airfoil. still couldnt get any positive outcomes. did u solve the case?

regards
gautam

[aridorinkato]

Hi everyone,
I cannot separate the flow region into laminar and turbulent for an airfoil. Would you guys help me out with the necessary proceedings for achieving this?

Thank you and Warm regards