low-medium Reynolds number

studen · January 21, 2015, 22:18

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

ericthefatguy · January 21, 2015, 23:02

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

studen · January 21, 2015, 23:17

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%

ericthefatguy · January 22, 2015, 00:25

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

studen · January 22, 2015, 00:35

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

January 21, 2015, 22:18	low-medium Reynolds number	#1
studen New Member studen Join Date: Jan 2012 Posts: 12 Rep Power: 14	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

January 21, 2015, 23:02		#2
ericthefatguy New Member Lean ("Eric") Fang Join Date: Jul 2013 Location: USTC, Hefei, P.R.C. Posts: 15 Rep Power: 12	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 __________________ A math geek with the passion for solving real-world problems. My website: http://home.ustc.edu.cn/~fanglean/

January 22, 2015, 00:25		#4
ericthefatguy New Member Lean ("Eric") Fang Join Date: Jul 2013 Location: USTC, Hefei, P.R.C. Posts: 15 Rep Power: 12	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 __________________ A math geek with the passion for solving real-world problems. My website: http://home.ustc.edu.cn/~fanglean/

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January 21, 2015, 23:17		#3
studen New Member studen Join Date: Jan 2012 Posts: 12 Rep Power: 14	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%

January 22, 2015, 00:35		#5
studen New Member studen Join Date: Jan 2012 Posts: 12 Rep Power: 14	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