how to calculate y+
How do you calculate y+ and in which range should it be?
Re: how to calculate y+
Y+ = Y/Nu * Utau
Y = distance from the nearest wall, Nu = Kinematic viscosity, Utau = skin friction velocity.
In the region nearest to the wall known as the viscous sublayer (Y+ <30) Utau is given by Newtons law -
Utau = sqrt((Mu*(du/dy))/rho)
Where Mu is dynamic viscosity = Nu*rho
rho - density
Outside the viscous sublayer the log-law is asssumed to aspply.
U+ = (1/K) log(y+) + C
U+ = (1/K) Log(Ey+)
With K= von Karman constant = 0.41 C = 5.5 or E = 9
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