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Old   March 5, 2009, 11:37
Default Urgent question for ILES
  #1
Feng
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I am doing an ILES simulation of flow around an airfoil. And I am using some high order resolution methods such as MUSCL or WENO 5rd. And I found the WENO could predict the turbulence behavers properly, however, it predict the seperation quite small. And the MUSCL predicted the larger speration. What's reason cause this problem? furthermore, I am confused a theory. Is that the large dissipation cause to the large seperation or small seperation? Thank you very much!
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Old   March 5, 2009, 13:49
Default Re: Urgent question for ILES
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Harish
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Is the code validated for some benchmark problem or you validating the code for flow around an airfoil ? Are you sure your grid is well refined to resolve the flow structures. If not check in the literature on the typical grid resolution employed for LES around airfoil.
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Old   March 5, 2009, 16:40
Default Re: Urgent question for ILES
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Feng
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Dear Sir,

Thanks for your responding. I am validating the code for flow around an airfoil. The Implicit LES is using high order resolution methods to provide the dissipation. So I think the simulation is quite sensitive to the numerical methods. I think my grid is refined enough. The grid is based on the typical grid for LES, and is 6 millon. When we using the classic LES, if the subgrid model provide large dissipation, what would be happened?

Thank you very much!
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Old   March 5, 2009, 18:03
Default Re: Urgent question for ILES
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Harish
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Did you try performing simulations in the same grid with a Smagorinsky model ? Using MILES is tricky as dissipation provided by the numerical method is unclear. What kind of flow field filtering do you perform to account for dissipation? Look for papers by Visbal et. al, Bogey et.al . They did some comparison studies between MILES, Smagorinsky and Dynamic smagorinsky using compact scheme and high-order explicit schemes with filtering. Also it might be easier to consider some benchmark cases such as channel flow as you would have to not worry much about capturing flow separation.

Harish
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Old   March 5, 2009, 18:38
Default Re: Urgent question for ILES
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Feng
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Dear Harish,

Thanks a lot for your earnest respondence. Could you provide the names of papers by Visbal et. al, Bogey et.al? My email address is: fxzf_2006@hotmail.com . Could we have more communication by email? Thank you very much!

Feng
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