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Old   March 18, 2008, 13:31
Default Airofil Again!
  #1
Steven
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Back again with another Airfoil problem!

I have been trying to get cl slopes for various different planforms of wing, the run converges fine until sepertaion occurs, at this point the simuation becomes transient as the residuals just oscilate. All ok so far. I monitored the lift and drag values during the solver and they also oscilate after seperation first occurs. I was assuming (as nuerical accuracy is not too important in my study) that the average between upper and lower oscialltions would be accepatable thus avoiding the need to run transient simulations. However my problem is that in post process the seperation is occuring (flow vis) as expected but the lift value just continues onwards with no regard for reality! Why is teh flow showing seperation but the force values are not reducing?

Any Ideas? Could I be missing the stall inbetween divisions of AOA? Can i take average values for lift between the osccialtions and if not, wont a transient simulation still have oscialitng lift values?

Any help much appreciated....dissertaion deadline looming.....

Steve

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Old   March 20, 2008, 06:27
Default Re: Airofil Again!
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Farid
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Hi Steven,

I am also facing the same problem. I am getting the Cl loop in the Cl vs AOA curve just opposite means during the upstoke the stall is expected but I am getting the stall during the downstroke. the lift is increasing even after the highest AOA.

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Old   March 22, 2008, 11:43
Default Re: Airofil Again!
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Steven
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Has anyone got any advice on this problem? Much appreciated!
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Old   April 1, 2008, 03:25
Default Re: Airofil Again!
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srikanth
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I am also facing the same problem, at the highest AoA flow has got saperated but lift was unable to drop?Can you pls suggest the procedure to resolve the problem
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Old   May 16, 2011, 02:53
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iswadi
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icemaniac178 is on a distinguished road
yes. i also have the same problem. refining the mesh does not help much to solve this issues. anybody? please help us!!
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