CMS-Flow:Wind Pressure

Wind

In CMS-Flow the wind shear stress is calculated as

     $\tau _{Wi}=\rho _{a}C_{d}|W|W_{i}$ 

The wind drag coefficient $C_{d}$ is calculated using the Hsu (1988)

     $C_{d}={\biggl (}{\frac {\kappa }{14.56-2\ln W}}{\biggr )}^{2}$ 

For measurements of wind speed made at heights other than 10 m, an approximation of the 10-m wind speed is (Shore Protection Manual 1984)

     $W=W_{z}{\biggl (}{\frac {10}{z}}{\biggr )}^{1/7}$ 

Symbol	Description	Units
$\tau _{W}$	Wind shear stress	Pa
$\rho _{a}$	Atmospheric density (~1.2 kg/m^3)	kg/m^3
$C_{d}$	Wind drag coefficient	none
$W$	10-min averaged wind speed at 10 m above the sea surface	m/sec
$\theta$	Wind direction	m/sec

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References

Hsu, S.A. (1988) Coastal meteorology. Academic Press, San Diego, CA.

Shore Protection Manual (1984) 4th ed., 2nd Vol, U.S. Army Engineer Waterways Experiment Station, U.S. Government Printing Office, Washington, DC.

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