Dear Jason,

I would like to know if I understood correctly that if I generate two bts files with the same grid, using the same seeds, but different timestep sizes, the realizations of the the turbulent wind field are different. I am referring to your remark in this post:

TurbSim Random Seeds:

Best regards,

Duncan van der Heul

Dear @Duncan.vanderHeul,

Yes, that is correct. The time step is inversely proportional to the highest frequency resolved.

Best regards,

Dear Jason,

Thank you for confirming that. Pardon my ignorance but I am still a bit confused:

Suppose I would receive a wind field realization as a bts file.

Then given all the *modelling* parameters of that particular input wind field realization (wind model, mean wind speed, turbulence intensity/intensities, reference height, shear model ) then in order to create a statistically equivalent turbulent wind field (with the same spectral density distribution) I would also need to know the exact temporal and spatial resolution used in the creation of the original bts file.

This is because the spectrum effectively depends on the temporal resolution.

Did I understand this correctly?

Thank you again and best regards,

Duncan

Dear @Duncan.vanderHeul,

The underlying spectrum (a continuous function of frequency) does not depend on the resolution. But within TurbSim, the spectrum is discretized based on the time step and simulation length (or equivalently, maximum frequency and frequency step). Changing the time step or simulation length would result a different discretization of the underlying spectrum.

Best regards,