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InflowWind Overview

Overview

This section presents a very brief synopsis of the operation of InflowWind, using information sourced directly from the InflowWind program documentation, reproduced with the permission of NREL. Refer to the NREL InflowWind documentation for further information.

InflowWind is a module for processing wind-inflow that has been coupled into OpenFAST. It supports several wind file formats including the following (corresponding to the WindType switch in the input file):

i.Steady wind (calculated internally using the Steady Wind Conditions section)

ii.Uniform wind (read externally from a Uniform Wind File)

iii.Binary TurbSim full-field wind file

iv.Binary Bladed-style FF wind file

v.Binary HAWC-style FF wind files

vi.User defined using the UserWind subroutine (to be supplied by and compiled by the end user; template IfW_UserWind.f90 file is provided)

The parameters in InflowWind’s primary input file are divided into several sections. The text of an example InflowWind input file is included in Example L01 - OC4 Semi-Submersible. Please note that there are multiple inputs with the same name in different sections of this input file (for example, RefHt, the reference height for the wind file). The parameters in each section are specific to the section in which they are defined. For example, the RefHt used in Steady Wind Conditions section is used only for the steady wind calculations; the RefHt in the HAWC-format section is used only for HAWC-style files.

At each time step, InflowWind receives from the driver code (either the standalone driver or the OpenFAST glue code) the coordinate position of various points and InflowWind returns the undisturbed wind-inflow velocities at these positions. There are no states in the module: each wind velocity component is calculated as a function of the input coordinate positions and internal time-varying parameters, undisturbed from interaction with the wind turbine. For full-field wind data types, InflowWind uses Taylor’s frozen turbulence hypothesis - valid only for stationary conditions - to translate wind defined in two-dimensional planes into three spatial dimensions, using the mean wind speed as the advection speed.

InflowWind OUTPUT Parameters

A list of all possible output parameters for the InflowWind module is presented below.