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 September 18, 2016, 23:53 About Newtons law of viscosity #1 New Member   krishna Atreyapurapu Join Date: Sep 2016 Location: Pune Posts: 2 Rep Power: 0 can anyone brief me, whether newton's law of viscosity works in laminar sub layers zone of Turbulent Boundary Layer ? if it is so why we are going to wall function in that layer.

September 19, 2016, 03:19
#2
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Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,777
Rep Power: 71
Quote:
 Originally Posted by krishnaA can anyone brief me, whether newton's law of viscosity works in laminar sub layers zone of Turbulent Boundary Layer ? if it is so why we are going to wall function in that layer.

the law is valid everywhere in the fluid and the wall function are used when you do not have a enough grid resolution to describe the boundary layer:

http://www.cfd-online.com/Wiki/Wall_functions

September 19, 2016, 04:28
#3
New Member

krishna Atreyapurapu
Join Date: Sep 2016
Location: Pune
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Quote:
 Originally Posted by FMDenaro the law is valid everywhere in the fluid and the wall function are used when you do not have a enough grid resolution to describe the boundary layer: http://www.cfd-online.com/Wiki/Wall_functions
Thank you for your replay, is it right idea to calculate the shear stress in laminar sub layers using liner relationship of newton law of viscosity, and compare for the results what i get from CFD.

My 2nd query is, if i have enough grid resolution near wall (keep the high accept ratio in maid) what make the sense to calculate wall shear stress using the wall function and acting it to the source term in momentum equation with out solve them directly.

 September 19, 2016, 05:06 #4 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,777 Rep Power: 71 I suggest to study the topics in this book https://www.scribd.com/doc/50191605/...ing-CFD-Wilcox

 Tags turbulence models, viscosity model, wall functions, wall y+