Help with Length Scale estimation/perforated plate

February 19, 2004, 17:01

Hi! I am a beginner, and I need some help with length scales. What exactly are length scales? I saw an equation of l=0.07L. What is l? Also for a perforated plate, is L the thickness of the plate? What I understand is that downstream of the perforated plate I need to have cells of length around 7% of the thickness of the plate. Is this correct?

February 20, 2004, 06:30

Please this is urgent. I cannot believe nobody knows anything about length scales?!?!

February 20, 2004, 07:40

l is the turbulence length scale, related to the size of the large eddies in a turbulent flow.

For a fully developed duct flow, l is restricted by the duct size, L, typically, the hydraulic diameter.

February 20, 2004, 09:24

Thanks Do you know anything about an obstruction in the flow like a perforated plate, what L would be in that case?

February 19, 2004, 17:01	Help with Length Scale estimation/perforated plate	#1
NHP Guest Posts: n/a	Hi! I am a beginner, and I need some help with length scales. What exactly are length scales? I saw an equation of l=0.07L. What is l? Also for a perforated plate, is L the thickness of the plate? What I understand is that downstream of the perforated plate I need to have cells of length around 7% of the thickness of the plate. Is this correct?

February 20, 2004, 06:30	Re: Help with Length Scale estimation/perforated p	#2
NHP Guest Posts: n/a	Please this is urgent. I cannot believe nobody knows anything about length scales?!?!

February 20, 2004, 07:40	Re: Help with Length Scale estimation/perforated p	#3
Anon Guest Posts: n/a	l is the turbulence length scale, related to the size of the large eddies in a turbulent flow. For a fully developed duct flow, l is restricted by the duct size, L, typically, the hydraulic diameter.

February 20, 2004, 09:24	Re: Help with Length Scale estimation/perforated p	#4
NHP Guest Posts: n/a	Thanks Do you know anything about an obstruction in the flow like a perforated plate, what L would be in that case?

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