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)

     $C_d=(\frac{\kappa }{14.56-2\ln W}{)}^2$ 

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)

     $W=W_z(\frac{10}{z}{)}^{1/7}$ 

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

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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