Subgrid Turbulent Kinetic Energy in LES

saqure · February 14, 2011, 01:06

Is it possible to compute the subgrid TKE in a LES model solved in Fluent ? How ?

I need this to evaluate the quality of the grid...

Thanks in advance

khosrow · August 31, 2012, 15:10

I have same problem. Could any one help? really appreciate it.

stuart23 · September 2, 2012, 11:19

From what I remember, turbulence is modeled on the subgrid scale, so your value of k should indicate the TKE FOR EDDIES ON THE SUBGRID SCALE. You will need to find a different way if you want to find the TKE of eddies resolved on the grid though.

Can you even call the energy in large eddies TKE? They are turbulent, but they are resolved, and are therefore not lumped together in a k value. I guess that they are often shown as part of spectral densities, so they do form part of the TKE. Just never thought about it like this....

Stu

khosrow · September 7, 2012, 16:44

Thank you very much Stu. I am looking for a way to get the contours of subgrid scale turbulent kinetic energy in ANSYS FLUENT 13. But seems it does not have this option in its post-processing? Are you aware about how to get this contour in FLUENT ANSYS 13? Thanks again

February 14, 2011, 01:06	Subgrid Turbulent Kinetic Energy in LES	#1
saqure New Member Khaled Join Date: Feb 2011 Posts: 3 Rep Power: 15	Is it possible to compute the subgrid TKE in a LES model solved in Fluent ? How ? I need this to evaluate the quality of the grid... Thanks in advance

September 2, 2012, 11:19		#3
stuart23 Senior Member Stuart Buckingham Join Date: May 2010 Location: United Kingdom Posts: 267 Rep Power: 25	From what I remember, turbulence is modeled on the subgrid scale, so your value of k should indicate the TKE FOR EDDIES ON THE SUBGRID SCALE. You will need to find a different way if you want to find the TKE of eddies resolved on the grid though. Can you even call the energy in large eddies TKE? They are turbulent, but they are resolved, and are therefore not lumped together in a k value. I guess that they are often shown as part of spectral densities, so they do form part of the TKE. Just never thought about it like this.... Stu khosrow likes this.

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August 31, 2012, 15:10		#2
khosrow New Member Khosrow Ebrahimi Join Date: Aug 2012 Posts: 8 Rep Power: 13	I have same problem. Could any one help? really appreciate it.

September 7, 2012, 16:44		#4
khosrow New Member Khosrow Ebrahimi Join Date: Aug 2012 Posts: 8 Rep Power: 13	Thank you very much Stu. I am looking for a way to get the contours of subgrid scale turbulent kinetic energy in ANSYS FLUENT 13. But seems it does not have this option in its post-processing? Are you aware about how to get this contour in FLUENT ANSYS 13? Thanks again