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incompressible airfoil simualtion

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Old   September 20, 2005, 17:39
Default incompressible airfoil simualtion
  #1
vyom
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Hi all, I am a new user in Fluent. I am simulating an incompressible airfoil using Gambit and Fluent. I meshed the airfoil using quad/map in gambit (300 cells around the airfoil, 75 in normal direction. The aifoil is placed in square box of 10 chords. In Fluent i used default Realisable K-e model. I used velocity inlet Boundary conditions on three sides and and pressure outlet on one side. I dont know but the drag and lift coefficients are not matching the experimental values even before stall ocuurs. I am not sure sure, what went worng. Could anybody please help me in thsi issue.

Regards Vyom
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Old   September 20, 2005, 17:44
Default Re: incompressible airfoil simualtion
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Riaan
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1) Check your reference values.

2) Use non-reflecting b.c. where possible e.g. Far Field - even if it means you have to solve compressible. Big debate on this...normally if you are M>0.3, it is assumed compressible - but even if your freestream is M<0.3, the local acceleration over your airfoil may be a lot faster.

3) Start with the S-A Turbulence model - should do well at subsonic / attached cases.
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Old   September 20, 2005, 17:52
Default Re: incompressible airfoil simualtion
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Vyom
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Hi Riaan, Actually i am using very low speed and for that Mach number will come to 0.1 maximum.

vyom
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Old   September 20, 2005, 17:56
Default Re: incompressible airfoil simualtion
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Riaan
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I did compressible down to Ma=0.1 .. but gets difficult to converge.

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Old   September 20, 2005, 18:07
Default Re: incompressible airfoil simualtion
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Vyom
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Hi Riaan, Actually this work has been done on other softwares using incompressbile calculations. i think i am doing some mistakes either in meshing or in solver. Can i send you my case files so that u can view it and advise me on that.

vyom
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Old   September 20, 2005, 20:50
Default Re: incompressible airfoil simualtion
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Riaan
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Before you send it - fdo this tutorial first: http://instruct1.cit.cornell.edu/cou...foil/index.htm

If you still can't get it right, I will have a look at your case.
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