about fast.farm set hubheight

[robytian]

Dear all, I have found the test of Tsinflow given in Fast. Farm, in which the .inp file points out that the hubheight is set to 175m, as we all know, the hub height of 5MW fan is 90m, I think it may be related to the change of wake plane, but is this setting reasonable? If I calculate the OC4-semi example and change the hubheight to 90, my grid width is 175 as required, it can also be calculated, but the following warning will be displayed during the calculation.

[jjonkman]

Dear @robytian,

The low- and high-resolution domains defined in FAST.Farm should be aligned with the domain defined in TurbSim to avoid excessive interpolation. I wouldn't change these arbitrarily.

When generating ambient wind for low-resolution domain of FAST.Farm, TurbSim input parameter HubHt should be set much higher than the actual hub height to ensure that the low-resolution domain is sufficiently larger than the rotor to accommodate wake meandering within FAST.Farm. For more information, see the "Inflow Wind Generation" section of the online FAST.Farm User's Guide and Theory Manual on OpenFAST readthedocs: https://openfast.readthedocs.io/en/main/source/user/fast.farm/ModelGuidance.html#inflow-wind-generation. See also: https://github.com/OpenFAST/openfast/issues/199.

Best regards,

[robytian]

Dear jjonkman， Thank you for your timely reply. I can understand that when I run fast. farm, the Hubheight set in Turbsim can not be set according to the actual hub height of the wind turbine, but can be set to be larger. Do I understand this correctly?

[jjonkman]

Dera @robytian,

Yes, that is correct when generating the ambient for the low-resolution domain of FAST.Farm using TurbSim.

Best regards,