Environment

Environment contains shared wind, wave, and soil models.

Wind

This module defines a wind speed profile at locations z, all wind speeds below z_0 are 0. The parameters Uref and zref allow for scaling of a profile shape. Specific implementations of this base component include PowerWind and LogWind. PowerWind assumes a power-law distribution of wind speeds of the form

\[U(z) = U_{ref} \left(\frac{z - z_0}{z_{ref} - z_0}\right)^\alpha\]

The logarithmic profile is of the form

\[U = U_{ref} \left[\frac{\log\left(\frac{z - z_0}{z_{roughness}}\right) }{\log\left(\frac{z_{ref} - z_0}{z_{roughness}}\right)}\right]\]

class wisdem.commonse.environment.WindBase[source]

class wisdem.commonse.environment.PowerWind[source]

class wisdem.commonse.environment.LogWind[source]

Wave

Hydrodynamic speed distributions are estimated using linear wave theory (LinearWaves). According to linear wave theory, the maximum horizontal velocity of a wave is given as

\[U_{current} = \omega \frac{h}{2} \frac{\cosh(k(z+D))}{\sinh(kD)} \cos(\omega t)\]

and the corresponding maximum acceleration is

\[A_{current} = \omega U_{current}\]

class wisdem.commonse.environment.WaveBase[source]

class wisdem.commonse.environment.LinearWaves[source]

Soil

The soil is assumed to not contribute any inertial or applied forces and only affects the stiffness of the foundation. The user may specify directions which are considered rigid. For the other directions, effective spring constants are estimated based on the soil properties (TowerSoil). A simple textbook model is used in this implementation [1]. The model allows for computation of an effective spring constant for all six degrees of freedom, each computed as a function of the shear modulus and Poisson’s ratio of the soil.

For example:

\[k_z = \frac{4 G r}{1- \nu} \left( 1 + 0.6(1-\nu)\frac{h}{r} \right)\]

where h is the depth of the foundation below the soil.

class wisdem.commonse.environment.SoilBase

class wisdem.commonse.environment.TowerSoil[source]