What is an eddy length scale?

bikooo3878 · January 2, 2019, 13:56

Good day everyone

I know this question might sound trivial, but I have been struggling and searching in books on turbulence to find a clear explanation to what an eddy size is? What is the characteristic length? and what is the length scale?

I've understood that there is a wide range of length scales for eddies, ranging integral turbulence to Kolmogrov. However, I can't quite grasp or feel what they actually refer to.

If someone could explain these terms or refer a book that illustrates their physical meaning, I'd be so grateful.

Thank you

mkh_sakr · January 3, 2019, 11:11

Hi,

According to my understanding (you should double check):

There are different eddies with different sizes in turbulent flow. The eddy which contains most of the energy has a length called the integral length scale. Kinetic energy is transferred between the eddies from the largest scale to the smallest eddy which has a length equal to Kolmogorov length scale and energy is dissipated into heat at this small scale.

you can see these presentation
http://www.bakker.org/dartmouth06/engs150/09-kolm.pdf

bikooo3878 · January 3, 2019, 18:29

Thank you for your answer. This presentation has helped a lot.

January 2, 2019, 13:56	What is an eddy length scale?	#1
bikooo3878 Member Mostafa Join Date: Sep 2016 Posts: 30 Rep Power: 9	Good day everyone I know this question might sound trivial, but I have been struggling and searching in books on turbulence to find a clear explanation to what an eddy size is? What is the characteristic length? and what is the length scale? I've understood that there is a wide range of length scales for eddies, ranging integral turbulence to Kolmogrov. However, I can't quite grasp or feel what they actually refer to. If someone could explain these terms or refer a book that illustrates their physical meaning, I'd be so grateful. Thank you

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January 3, 2019, 11:11		#2
mkh_sakr New Member Join Date: Nov 2011 Posts: 13 Rep Power: 14	Hi, According to my understanding (you should double check): There are different eddies with different sizes in turbulent flow. The eddy which contains most of the energy has a length called the integral length scale. Kinetic energy is transferred between the eddies from the largest scale to the smallest eddy which has a length equal to Kolmogorov length scale and energy is dissipated into heat at this small scale. you can see these presentation http://www.bakker.org/dartmouth06/engs150/09-kolm.pdf

January 3, 2019, 18:29		#3
bikooo3878 Member Mostafa Join Date: Sep 2016 Posts: 30 Rep Power: 9	Thank you for your answer. This presentation has helped a lot.