How wind shear is modeled in WT_Perf?

I’d like to consider wind shear effects on performance optimization of a wind turbine. I guess WT_Perf should take wind shear into account by averaging its effects over a complete period (360 deg.) with a specific step size.
Is this right? If true, then how much this step size is?
So many thanks.

Dear Hossein,

I apologize for not keeping up with the forums, but it’s been hard trying to find some time to do so.

WT_Perf is a steady-state, non-time-marching code. There is no time step.

You specify the number of sectors to use in the simulation. If you have no shear, there is no need to use more than one sector (unless you have a skewed wake due to yaw error or shaft tilt), as the wind speed is the same across the rotor. The more sectors you specify with sheared flow, the better the shear definition. If you specify just two sectors, they will cover the left and right half of the rotor and the elevations used will be the centers of those sectors, which means hub height and so it would not see any shear. Because of that, I force the number of sectors to be a minimum of four for sheared analyses. This causes the analysis to be done at 45, 135, 225, and 315 degrees, with zero being up. I recommend you use more than the minimum of four sectors, but keep in mind that the execution time is proportional to the number of sectors. That’s not really noticeable for a single run, but it can add up if you are running many cases. You have to balance pain with accuracy.


Dear Mr. Buhl,
Thank you so much for your precise and thorough answer.

Best Regards,