CMS-Flow:Wind Pressure: Difference between revisions

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The wind drag coefficient <math> C_d </math> is calculated using the Hsu (1988)
The wind drag coefficient <math> C_d </math> is calculated using the Hsu (1988)


       <math> C_d = \biggl ( \frac{\kappa}{14.56 - 2 \ln W}\biggr ) ^2 </math>  
       <math> C_d = \biggl ( \frac{\kappa}{14.56 - 2 \ln W} \biggr ) ^2 </math>  


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)
      <math> W = W_z ^2 \biggl ( \frac{10}{z} \biggr )^{1/7} </math>


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Revision as of 14:52, 14 May 2010

Wind

In CMS-Flow the wind shear stress is calculated as

     τWi=ρaCd|W|Wi 

The wind drag coefficient Cd is calculated using the Hsu (1988)

     Cd=(κ14.562lnW)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=Wz2(10z)1/7 
Symbol Description Units
τW Wind shear stress Pa
ρa Atmospheric density (~1.2 kg/m^3) kg/m^3
Cd Wind drag coefficient none
W 10-min averaged wind speed at 10 m above the sea surface m/sec
θ Wind direction m/sec



References

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


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