# ACTUAL Velocity profile in the viscous layer

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 March 20, 2014, 03:07 ACTUAL Velocity profile in the viscous layer #1 New Member   Join Date: Mar 2014 Posts: 5 Rep Power: 12 Can anyone sum up all the differences in actual velocity profile (not the normalized one) when a "log-law" wall condition is applied to if it had been a theoretical laminar or turbulent profile here ?

 March 20, 2014, 03:50 #2 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,793 Rep Power: 71 in the viscous sublayer you get a laminar profile, very different from the log-law as it behaves like u+=y+

 March 20, 2014, 04:17 #3 New Member   Join Date: Mar 2014 Posts: 5 Rep Power: 12 No. I am talking about y+ <30.....where both laminar and turbulent exist. What I would like to know is how this normalized log-law eqn....u+ = (y+ / k) + c gets plotted in a u v/s. y plot, not u+ v/s. y+......and also if I could get a plot of our well known turbulent and laminar profiles on the same plot, it would be very helpful because I want to compare all the three....for ex:- which one stays up or goes down for how long.....Please assume any relevant value for k and c above to give me this plot ?

March 20, 2014, 04:24
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Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,793
Rep Power: 71
Quote:
 Originally Posted by Ankur Sawhney No. I am talking about y+ <30.....where both laminar and turbulent exist. What I would like to know is how this normalized log-law eqn....u+ = (y+ / k) + c gets plotted in a u v/s. y plot, not u+ v/s. y+......and also if I could get a plot of our well known turbulent and laminar profiles on the same plot, it would be very helpful because I want to compare all the three....for ex:- which one stays up or goes down for how long.....Please assume any relevant value for k and c above to give me this plot ?

just assume to know u_tau and the viscosity of the fluid, you can transform the laws (u+,y+) in (u,y)...

 March 20, 2014, 04:34 #5 New Member   Join Date: Mar 2014 Posts: 5 Rep Power: 12 Yes....sure.Thank you Mr. Denaro

 Tags viscous layer, wall boundary condition, wall distance