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#1 |
New Member
SSSSS
Join Date: Jun 2011
Posts: 29
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Hi,
I am calculating TKE budget equation by using solutions from LES simulation. From filtered momentum equation of incompressible flow,(Please note than variables are filtered/resolved value and filter symbol is omitted) ![]() By using linear eddy-viscosity model, ![]() ![]() I could get tke budget equation using the above equation with time averaging like RANS ![]() where bar means time mean and tke ![]() ![]() this equation is basically identical to the counterpart from RANS except for ![]() ![]() When I applied this equation to the results of flow around a circular cylinder, I found there is imbalance around shear layer otherwise balance is made. I have checked my discretizing each term and it looks good. When I compared resolved turbulent stress (u'v', u'w' and v'w') to subgrid stress ( ![]() Thanks in advance. Last edited by doctorWho; March 12, 2014 at 10:04. |
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#2 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
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According to the book of Sagaut, the equations 3.30 to 3.33 are in the form you should use. Now, is your solution statistically steady? What about production and dissipation budget?
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#3 |
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SSSSS
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FMDenaro
Yes, the solution is statistically steady. As I understand, equation 3.30 of Sagaut is equation for instantaneous resolved kinetic energy not resolved turbulent kinetic energy. Also equation 3.33 is equation for unresolved kinetic energy but mine is equation for resolved turbulent kinetic energy which is following the time averaging of RANS. Do you mean that I cannot use tke equation in LES? As I check production and dissipation around shear layer, production is about 10 times larger than dissipation. |
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#4 |
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Filippo Maria Denaro
Join Date: Jul 2010
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To be more clear, when you compute a LES solution your velocity field is
ULES = G*u = u -u'LES then you can compute the satistical average <ULES> = <u> -<u'LES> Therefore, being <u> = URANS = u -u'RANS <ULES> = URANS -<u'LES> You can see the difference ... |
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