ACTUAL Velocity profile in the viscous layer

Ankur Sawhney · March 20, 2014, 04:07

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 ?

FMDenaro · March 20, 2014, 04:50

in the viscous sublayer you get a laminar profile, very different from the log-law as it behaves like u+=y+

Ankur Sawhney · March 20, 2014, 05:17

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 ?

FMDenaro · March 20, 2014, 05:24

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)...

Ankur Sawhney · March 20, 2014, 05:34

Yes....sure.Thank you Mr. Denaro

March 20, 2014, 04:07	ACTUAL Velocity profile in the viscous layer	#1
Ankur Sawhney 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 ?

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March 20, 2014, 04:50		#2
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,896 Rep Power: 73	in the viscous sublayer you get a laminar profile, very different from the log-law as it behaves like u+=y+

March 20, 2014, 05:17		#3
Ankur Sawhney 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, 05:34		#5
Ankur Sawhney New Member Join Date: Mar 2014 Posts: 5 Rep Power: 12	Yes....sure.Thank you Mr. Denaro