Kolmogorov scale .... LES

maphd · August 8, 2005, 09:45

Hello,

I am doing some LES of a reacting flow and I need to calculate some values. How can I calculate the Kolmogorov timescale and the Kolmogorov Reynolds Number? Also how can I calculate the dissipation rate (epsilon)?

Thanking you all.

August 12, 2005, 01:01

I guess you need read a textbook. Select large scales, estimate the dissipation scales by using the Komogorov relations and then estimate epsilon.

maphd · July 2, 2015, 20:48

Hello LESer,
Did you find how to calculate kolmogorov length scale in LES? I really appreciate if you could give me some help on this.
Thanks,

FMDenaro · July 3, 2015, 04:38

there is no Kolmogorov scale in LES ! the smallest scale is defined by the filter lenght, not by the molecular viscosity and lies in the inertial subrange.

maphd · July 3, 2015, 06:36

FMDenaro thank you very much for your reply. Can you tell me a way to calculate this smallest length scale? I just need a way to calculate something similar to kolmogorov length scale? Can I write a user defined function for kolmogorov length scale maybe? If you could give me some help on this I really appreciate it.
Thank you very much

FMDenaro · July 3, 2015, 06:54

Kolmogorov scale is dictated by the physics of the problem.
LES provides the smallest scale at about twice grid step size. That has nothing to do with kolmogorov scale

maphd · July 3, 2015, 07:01

FMDenaro, thank you very much for your reply. Is there any way I can calculate and see that smallest scale in Fluent? I really appreciate your help. I just need to calculate something corresponding to kolmogorov length scale in LES. Thanks a lot.

August 8, 2005, 09:45	Kolmogorov scale .... LES	#1
LESer Guest Posts: n/a	Hello, I am doing some LES of a reacting flow and I need to calculate some values. How can I calculate the Kolmogorov timescale and the Kolmogorov Reynolds Number? Also how can I calculate the dissipation rate (epsilon)? Thanking you all. maphd likes this.

August 12, 2005, 01:01	Re: Kolmogorov scale .... LES	#2
yuan Guest Posts: n/a	I guess you need read a textbook. Select large scales, estimate the dissipation scales by using the Komogorov relations and then estimate epsilon.

July 3, 2015, 04:38		#4
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,849 Rep Power: 73	there is no Kolmogorov scale in LES ! the smallest scale is defined by the filter lenght, not by the molecular viscosity and lies in the inertial subrange. maphd likes this.

July 3, 2015, 06:54		#6
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,849 Rep Power: 73	Kolmogorov scale is dictated by the physics of the problem. LES provides the smallest scale at about twice grid step size. That has nothing to do with kolmogorov scale maphd likes this.

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July 2, 2015, 20:48		#3
maphd Member Join Date: May 2013 Posts: 32 Rep Power: 13	Hello LESer, Did you find how to calculate kolmogorov length scale in LES? I really appreciate if you could give me some help on this. Thanks,

July 3, 2015, 06:36		#5
maphd Member Join Date: May 2013 Posts: 32 Rep Power: 13	FMDenaro thank you very much for your reply. Can you tell me a way to calculate this smallest length scale? I just need a way to calculate something similar to kolmogorov length scale? Can I write a user defined function for kolmogorov length scale maybe? If you could give me some help on this I really appreciate it. Thank you very much

July 3, 2015, 07:01		#7
maphd Member Join Date: May 2013 Posts: 32 Rep Power: 13	FMDenaro, thank you very much for your reply. Is there any way I can calculate and see that smallest scale in Fluent? I really appreciate your help. I just need to calculate something corresponding to kolmogorov length scale in LES. Thanks a lot.