Dear NREL Team,
I hope you are well.
I have a few questions regarding the FAST.Farm wake planes and their relationship with DT_Low, as detailed in the FAST.Farm manual:
- The manual states that “The low-resolution domain in FAST.Farm is primarily responsible for wake meandering and merging.” Based on this, I understand that the low-resolution wind fields are convected at the DT_Low time step, and the wake planes are updated simultaneously. If this interpretation is correct, could you clarify why the manual suggests generating the low-resolution wind field using DT_High when using the multi-scale TurbSim wind fields approach? Is this recommendation mainly to obtain the hub-height wind time series needed for generating the high-resolution wind fields? If so, does this imply that some information from the low-resolution TurbSim domain might be lost during the FAST.Farm simulation because of using DT_Low instead of DT_High for interpolating the low-resolution wind field planes?
- Regarding the wake planes in the axisymmetric wake solution, my understanding from the manual is that the wake planes are updated every DT_Low seconds, with their propagation speed varying depending on their position within the farm (as opposed to the ambient wind planes, which propagate at V_advect). To estimate “NumPlanes,” the manual advises using V_dash, the average convection speed of the wake.
- Is it correct to assume that at each DT_Low interval, a new wake plane is emitted behind the turbine, and that each wake plane is then propagated downstream across the “NumPlanes” planes?
- Could you please confirm whether my understanding of the wake plane dynamics is accurate?
- Lastly, could you provide guidance on how to track the location of the wake center at a fixed distance downstream?
Thank you very much for your time and assistance in addressing these questions.
Kind regards,