Symmetry of the wake behaviour in FAST.Farm

Wind & Water Wind Farm Modeling
1

Dear all,

I hope this finds you well.

I have a question regarding the wake model in FAST.Farm. I am planning to run several simulations involving two wind turbines initially aligned with the global axial direction, where I vary the wind direction between -15 to 15 degrees by rotating the wind farm.

Specifically, I want to know if the wake effects are symmetrical around the zero-degree wind direction. If this symmetry exists, could I simplify my testing by only simulating wind directions from 0 to 15 degrees and assume that the results for -15 to 0 degrees would be the same?

I understand that some differences might occur due to the distribution of turbulent structures in the wind field. However, my main concern is whether the wake model in FAST.Farm inherently causes any asymmetry in wake behaviour that I need to consider in my simulations.

Kind regards

2

Dear @Abdulbaset.Alazhare,

FAST.Farm could include asymmetry in the wake, depending on the settings you are using. The polar wake model is always axisymmetric about the wake centerline, but the wake centerline could deflect more to one side if the horizontal wake deflection correction model. The curled wake model is not axisymmetric, and if you have Swirl enabled, the torque will shift the asymmetry (kidney shape of the wake resulting from skewed inflow) to one side depending on the skew axis and torque.

Best regards,

3

Thank you, @Jason.Jonkman.

4

Dear @Jason.Jonkman, does the wake in FAST.Farm rotate as it travels through the wind farm?

Kind regards

5

Dear @Abdulbaset.Alazhare,

The axisymmetric polar wake model of FAST.Farm does not include wake rotation, but the curled wake model does include wake rotation when Swirl is enabled in FAST.Farm.

Best regards,