Source code for pyts.profModels.power

"""
The NWTC power-law profile model.
"""
from .base import profModelBase, profObj


class nwtc(profModelBase):

    r"""Power-law wind profile model.

    .. math::

           \bar{U}(z) = U_{ref} * ( z / Z_{ref} )^{PLexp}

    Parameters
    ----------
    URef :      float
                Reference velocity for the wind profile [m/s].
    Zref  :     float
                Reference height of the reference velocity [m].
    PLexp :     float
                The power-law exponent to be utilized for this
                simulation [non-dimensional], default=1/7.

    """

    def __init__(self, Uref, Zref, PLexp=1. / 7.):
        self.Uref = Uref
        self.Zref = Zref
        self.PLexp = PLexp

    def _sumfile_string(self, tsrun, ):
        sumstring_format = """
        Profile model used                               =  {dat.model_desc}
        Reference velocity (URef)                        =  {dat.Uref:0.2f} [m/s]
        Reference Height (Zref)                          =  {dat.Zref:0.2f} [m]
        Power-low exponent (PLexp)                       =  {dat.PLexp:0.2f}
        """
        return sumstring_format.format(dat=self)

    def model(self, z):
        """
        The function for calculating the mean velocity profile.
        """
        # Note: this function is separated from the __init__ routine so that it
        # can be utilized by other modules
        return self.Uref * (z / self.Zref) ** self.PLexp

    def __call__(self, tsrun):
        """
        Create and calculate the mean-profile object for a `tsrun`
        instance.

        Parameters
        ----------
        tsrun :         :class:`.tsrun`
                        A TurbSim run object.

        Returns
        -------
        out :           :class:`.profObj`
                        A power-law wind-speed profile for the grid in `tsrun`.

        """
        out = profObj(tsrun)
        out[0] = self.model(out.grid.z)[:, None]
        return out