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Old   August 16, 2002, 08:54
Default Viscous sublayer thickness
Bo Busk Jensen
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Hallo All

I have seen in the literature that the thickness of the viscous sublayer in a fully developed flow is approx. y+ = 10. But is there any equation for the thickness as a function of the distance from a pipe inlet??



PS.: I know this i snot a Fluid Mechnics Forum - is there one where I could ask instead??
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Old   August 17, 2002, 09:15
Default Re: Viscous sublayer thickness
Axel Rohde
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I don't know the answer to your question, but you are definitely in the right place here. You can also try which also has a discussion board. I believe you have to register first though.
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Old   August 18, 2002, 14:50
Default Re: Viscous sublayer thickness
Jan Rusaas
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Hej Bo'

Have you checked the book by schlichting, (not sure if it is spelled correct don't have the book on my desk) boundary layer theory. There exist news groups with fluid mechanics, sci.mech.fluids and some other relevant sci.geo.fluid sci.physics.computational.fluid-dynamics

Regards Jan
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Old   September 10, 2002, 18:31
Default Re: Viscous sublayer thickness
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Here is a crude way to estimate. This is based upon flat plate theory:

for a y+ value of 10 you are right at the begining of what is known as the log region in the wall law plot.

yu*/nu=y+ u*=sqrt(cf/2)Ue cf=.664/sqrt(Rex) Rex=(rho*V*x)/Nu

Ue = edge velocity rho=density nu=viscosity x=length downstream of the entrance.

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Old   April 13, 2011, 01:25
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Does there exist a rule or a law how many boundary layers should be built to model the viscous sublayers?
I can only find the dimensionsless wall distance. But there is no information about how many layers are required.

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