Monopile
=====================

The :code:`monopile` is defined similar to the :code:`tower`.

.. literalinclude:: ../../test/turbine/IEA-15-240-RWT.yaml
    :start-after: monopile
    :end-before: airfoils

:code:`reference_axis` : Object
    The field :code:`reference_axis` describe the three-dimensional shape of the reference axis of the monopile via three sub-fields, namely :code:`x`, :code:`y`, and :code:`z`. The three sub-fields contain the pairs of arrays :code:`grid` and :code:`values`. The former is nondimensional, while the latter is expressed in meters. :code:`x`, :code:`y`, and :code:`z` are expressed in the monopile reference system, with :code:`x` parallel to the ground pointing downwind, :code:`y` parallel to the ground and to the rotor plane, and :code:`z` perpendicular to the ground pointing upwards. Standard monopiles are only defined along :code:`z`.

:code:`outer_diameter.values` : Array of floats, m
    Diameters of the monopile defined from monopile base (grid = 0) to monopile top (grid = 1).

:code:`drag_coefficient.values` : Array of floats
    This is the equivalent drag coefficient used to compute the aerodynamic forces generated by the monopile immersed in the flow. Standard aeroelastic solvers use this parameter.

:code:`outfitting_factor` : Float
    Multiplier of monopile mass to account for the mass of the auxiliary systems, such as paint or extra structural elements. This can be used to convert the mass of the steel cylinders to the total mass of the monopile.

The field :code:`layers` mimic the same field of the blade/tower.