how to calculate Turbulent Length Scale

nuimlabib · August 17, 2009, 03:16

Could any one please guide me on how to calculate the turbulent length scale in external flow..While doing k-omega turbulent modeling I chose Turbulent Intensity and Turbulent Length Scale Option. i enter the turbulent intensity about 0.07%. Please Help me in this regard. Thanks in Advance

franck · August 17, 2009, 04:50

In the article by Lutz and al (AIAA J, Vol.45(4), p.779, 2007), among others, you can find an approximate formula combining different results from isotropic turbulence, Von Karman spectrum, etc... It reads:
L = 0.387*(k_t^(3/2))/epsilon.

You can also get from this the outer integral scale (or characteristic length of energy bearing eddies) as:
Lambda = L/0.7468
(See the book by Mathieu and Scott, Introduction to Turbulent Flow, 2000)

Hope this helps.

nuimlabib · August 18, 2009, 05:22

ok thanks a lot of for your suggestion mr frank..

August 17, 2009, 03:16	how to calculate Turbulent Length Scale	#1
nuimlabib New Member labib Join Date: Jun 2009 Posts: 25 Rep Power: 17	Could any one please guide me on how to calculate the turbulent length scale in external flow..While doing k-omega turbulent modeling I chose Turbulent Intensity and Turbulent Length Scale Option. i enter the turbulent intensity about 0.07%. Please Help me in this regard. Thanks in Advance

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August 17, 2009, 04:50		#2
franck New Member Join Date: Jul 2009 Posts: 3 Rep Power: 17	In the article by Lutz and al (AIAA J, Vol.45(4), p.779, 2007), among others, you can find an approximate formula combining different results from isotropic turbulence, Von Karman spectrum, etc... It reads: L = 0.387*(k_t^(3/2))/epsilon. You can also get from this the outer integral scale (or characteristic length of energy bearing eddies) as: Lambda = L/0.7468 (See the book by Mathieu and Scott, Introduction to Turbulent Flow, 2000) Hope this helps.

August 18, 2009, 05:22		#3
nuimlabib New Member labib Join Date: Jun 2009 Posts: 25 Rep Power: 17	ok thanks a lot of for your suggestion mr frank..