Law of the wall

(Difference between revisions)
 Revision as of 14:53, 5 September 2011 (view source)GeeZ (Talk | contribs) (changing "B" constant in formula to "C" constant so that the formula gets consistent with the "Where :" list of parameters)← Older edit Revision as of 20:15, 5 September 2011 (view source)Peter (Talk | contribs) m (Changed constant in formula and table from C to B to match formula in plot)Newer edit → Line 1: Line 1: In the log layer the velocity profile can be estimated with the log law: In the log layer the velocity profile can be estimated with the log law: - :$u^+ = \frac{1}{\kappa} \, ln(y^+) + C$ + :$u^+ = \frac{1}{\kappa} \, ln(y^+) + B$ and close to the wall in the viscous sublayer and close to the wall in the viscous sublayer Line 17: Line 17: |$\kappa$ || von Karman's constant ($\approx 0.41$) |$\kappa$ || von Karman's constant ($\approx 0.41$) |- |- - |$C$ || Constant ($\approx 5.1$) + |$B$ || Constant ($\approx 5.1$) |} |}

Revision as of 20:15, 5 September 2011

In the log layer the velocity profile can be estimated with the log law:

$u^+ = \frac{1}{\kappa} \, ln(y^+) + B$

and close to the wall in the viscous sublayer

$u^+ = y^+$

Where:

 $u^+$ Dimensionless velocity $y^+$ Dimensionless wall distance $\kappa$ von Karman's constant ($\approx 0.41$) $B$ Constant ($\approx 5.1$)

We should have a lin-log plot here of a typical turbulent boundary layer to illustrate where the log-law is valid, anyone have one handy?

In the image y is replaced with the letter n.