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Help with Turbulence Model

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Old   June 7, 2007, 02:40
Default Help with Turbulence Model
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Yashwant Ganti
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Hello, I am trying to model a 2-D airfoil+flap geometry in FLUENT, using a k-epsilon turbulence model(with default values).I am using a C type grid, as described in the cornell university tutorial: http://instruct1.cit.cornell.edu/cou...luent/airfoil/ The following is my grid info: Grid Size

Level Cells Faces Nodes Partitions

0 15810 31946 16135 1

1 cell zone, 7 face zones. After i run the simulation and get a fairly convergent solution, i took a look at the y+ values, when i pressed compute, the min was 0 and the max was 50000. I then tried to adapt the grid (Hanging Node adaption) with y+ min of 30( as suggested in the literature) and max at default value of 500. Some regions were marked for adaption, both round the airfoil and flap. When I ran the simulation with the new mesh, I still have my min at 0 and max is at 49876 now. Apart from this I have turbulent viscosity limited to viscosity ratio in 5 cells at the beginning of the iteration, which increases to 55 cells at the end of the iteration(2500 is the number of iterations). When i plot the values of TVR for various zones, i find that this is happening at the outlet. Is this affecting my solution?. The Cl values I am obtaining are around 20% less than what have been validated experimentally for a similar airfoil and flap. ( the airfoil i am using is similar to the NACA 23015, with a slotted T.E flap). Could some one please suggest how i could improve my model. Thanks,Yashwant.
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