Winds not only creates wind induced waves, but also directly generates loads on marine structures when the superstructure (portion above the mean water surface) is significant.
Winds have three main features:
A mean velocity: An average wind speed over a given period of time (mostly 1 hour) at a standard height above water surface (usually 10m);
A mean speed profile: The velocity of the mean wind variation with height from water surface;
Turbulence or gusts: The time-varying wind speed about the mean speed.
For more information, see [4].
It is assumed that there is no vertical component of the wind velocity in the fixed reference axes (FRA): the wind speed is always in the OXY (horizontal) plane of the FRA.
In Aqwa, the wind drag force is calculated using the wind speed at 10m above mean water surface. If some other reference height is input, Aqwa will firstly calculate the corresponding wind speed at 10m.