WRG Interpolation from fixed CFD heights to required height to use within Windfarmer

[Pablo Faúndez]

Hello,

I need a wind resource grid (wrg) at 112m high (turbine hub height) as an input to Windfarmer. Wasp CFD calculates wind resource at fixed heights (5, 10, 20, 33, 48, 65, 80, 100, 120, 150, 200, 250 and 300 m). How is the mathematical process of interpolation from these fixed heights to the required wrg height within Wasp CFD? 

 

Thanks!

[Rogier]

WAsP CFD (I guess you are talking about the cfdres files) only calculates speedup factors from the terrain. There is no way to get from those files to a wrg file because that format also needs to know the wind distribution (e.g. frequency that the wind is blowing from a certain wind direction sector), which is not present in the cfdres files. So to get from those to the wind resource at 112 m, you will just need to run WAsP itself. That means it does all the steps in the generalization and downscaling of WAsP, using log profile, geostrophic drag law and stability effects. You can read more about those vertical and horizontal extrapolation steps in the European wind atlas and some more recent papers describing the stability model:

https://backend.orbit.dtu.dk/ws/portalfiles/portal/112135732/European_Wind_Atlas.pdf

https://link.springer.com/article/10.1007/s10546-023-00803-3

[Pablo Faúndez]

Hi Rogier, Thanks for your answer and links to the articles.

So I presume WAsP uses the speedups at different fixed heights from the cfdres files in order to get a better log profile and a better estimate of the geostrophic wind than with the IBZ model. Is this correct?

Thanks!

[Rogier]

Yes exactly :)