Decouple Hub Height from Grid in TurbSim

[jjonkman]

In TurbSim, the location and extent of the full-field grid is set based on input parameters HubHt, GridHeight, and GridWidth. Together with the wind profile, the HubHt is used by TurbSim as the reference height for the wind speed used to define the wind-speed standard deviations and spatial coherence in the IEC turbulence models, as well as the advection speed (in InflowWind) for all models. This is often OK because one often wants the grid set based on the actual wind turbine hub height. But when using TurbSim to generate turbulent wind inflow for FAST.Farm, one often wants to set the grid well beyond the rotor (both laterally and vertically) to consider the meandering of wakes. As a result, when using TurbSim to generate turbulent wind inflow for FAST.Farm, it is often necessary to set TurbSim input HubHt different from (typically much higher than) the actual wind turbine hub height. Thus, the resulting wind-speed standard deviations and spatial coherence in the IEC turbulence models, as well as the advection speed (in InflowWind) will likely not be what is expected. To address this issue, TurbSim should be changed so that the HubHt input is decoupled from the specification of the full-field grid.

[RuiliangWang]

Is fast.farm available?

[jjonkman]

@RuiliangWang,

Not yet. See the following post on our forum for more information: https://wind.nrel.gov/forum/wind/viewtopic.php?f=13&t=2117&p=11820.

From the list of topics we are still working on in preparation for a release from my post dated Sep 24, 2018, we have recently completed assessing the sensitivity of FAST.Farm predictions to the use of synthetic versus high-fidelity precursor ambient wind data and are presenting a paper on that topic this week at the AIAA SciTech 2019 conference. We are currently working on the other items in this list.

Best regards,

[JianYZHANG]

@jjonkman

I want to confirm whether the decoupled problem has been solved in the updated TurbSim submodule? The version of TurbSim I employed is V2.00.00 updated in 2016 and any newer release? Thx

Best regards,

[jjonkman]

Dear @JianYZHANG,

TurbSim has not yet been changed to decouple the hub height from the grid as requested above.

Regarding newer releases of TurbSim, the TurbSim source code is included in this OpenFAST repository. The version of TurbSim included in this OpenFAST repository is based on TurbSim v2.00.07a-bjj, with a couple minor updates; the input files are the same as for TurbSim v2.00.

Best regards,

[JianYZHANG]

Dear @jjonkman,

Got it, and Thank you for your reply.

Best regards,