Von Kármán constant

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A unitless constant describing the logarithmic velocity profile of a turbulent fluid near a no-slip boundary. The equation for such boundary layer flow profiles is:

$u=\frac{u_{\star}}{k}\ln\frac{z}{z_0}$

where $u$ is the velocity at height $z$ above the roughness height $z 0$ where $u$ goes to 0. $k$ is the von Kármán constant (typically the value 0.41 is used), and $u_{\star}$ is the "friction velocity" which describes the amount of turbulence in the flow.

Used in boundary layer meteorology to calculate fluxes of momentum, heat and moisture from the atmosphere to the land surface. Named for Theodore von Kármán.

[edit] References

Bonan, G. B. 2005. Land Surface Model (LSM 1.0) for Ecological, Hydrological, Atmospheric Studies. Model product. Available on-line [1] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.