Wind Shear

Wind shear is the variation of steady state mean wind speed with height. Three alternative models are provided, to relate the wind speed \(V(h)\) at height \(h\) above the ground to the wind speed \(V(h_0)\) at some reference height \(h_0\).

No flow shear

The user can select a uniform flow field in which case the mean wind speed does not vary with height due to wind shear contribution.

Exponential model

This model is defined in terms of a wind shear exponent \(\alpha\):

\[ \begin{equation} V(h)=V(h_0)\left(\frac{h}{h_0}\right)^\alpha \end{equation} \]

Specifying the exponent as zero results in no wind speed variation with height.
The exponential wind shear model is also known as the power law model in other references.

Logarithmic model

This model is defined in terms of the ground roughness length \(z_0\):

\[ \begin{equation} V(h)=V(h_0)\left(\frac{log{(}h/z_0)}{log{(}h_0/z_0)}\right) \end{equation} \]

User-defined model

A different shear profile may be defined by entering a lookup table giving a wind speed multiplication factor as a function of height. To obtain the required speed at the reference height, the multiplication factor must be 1.0 at the reference height.

Last updated 30-08-2024