low-medium Reynolds number
 

Hi,

i am trying to slove a low reynolds number flow problem on NACA 4415 (Re 2e5), i am having lot of difficulties in validating with the previous experimental values. currently using SA turbulence model and aoa range is from 0 to 20 deg, the lift is not exactly matching and the drag is over predicted. I am currently using Fluent 14.5 and Fluent 15.0 can you please suggest which turbulence model will be best suited to get closer results to experiment. Further more i am planning to study the 3D effects later.

Thanks for the help

Hi,

You might want to try k-omega SST model with low-Re correction. And also make sure that your mesh is well-resolved at boundary layers, and leading & trailing edges.

Hope this helps,
Eric

thanks for the reply

eric,

i have tried all the 2 equation 4 equation transition but the best results are given by SA i dont know why SA offers closer solution to the expt, but the only deal breaker is the increase in drag by 18%

Hi,

May I know which literature you are comparing your simulation results with?

From my own experience dealing with low-Re airfoil simulations, the free-stream turbulence properties play a huge role in the overall aerodynamic behavior, so you need to make sure your simulation free-stream turbulence properties set at the inlet/farfield b.c. are identical to that of the experiments.

Hope this helps,
Eric

C. Ostowari and D. Naik, “Post Stall Studies of Untwisted Varying Aspect Ratio Blades With an NACA 4415 Airfoil Section—Part I,” Wind Engineering, vol. 8, no. 3, pp. 176–194, 1984