Timm

Hallo WAsP Team, I would like to know how the reference roughness is calculated exactly. I have calculated a roughness rose in WAsP 10.2. Therefore I got the roughness length for each different section in each sector. In the Site effect results I got the reference roughness for each sector. And I can't imagine how this is done. I have read the WAsP Help file but it doesn't give me the answer I was looking for. How are the sections weighted? And how is the reference roughness calculated? Thank you for your help. Best regards. Timm

Hallo Morten, Thank you very much for your detailed explanations. But i have a few more questions. If i want to calculate only the ambient turbulence, i don't need the wind atlas file and i don't need WAT? The wind atlas file is no Input for LINCOM or the turbulence model by Mann? It is only used for the averaging(effecitve turbulence intensity), as you said? What is the input for the LINCOM model? The Orography and roughness data? I hope i get it right this time: To Predict the ambient turbulence intensity at a site: Orography and roughness data are used as input for the LINCOM flow model. The flow results are used as input for the turbulence model by Mann to predict the ambient turbulence intensity. Which also needs the orography and roughness data. Then WAT adapts the WEng turbulence results to the IEC. And adds wake turbulence and calculates effective turbulence. And therefore i need the wind altas file. So the WEng turbulence results (TI_WEng) are saved in a .wtr file. But are this results in the .wtr file, the ambient turbulence intensity in the different sectors at 15m/s? Or is the ambient turbulence intensity at 15m/s given by: I(15)=(15+a*u)*TI_WEng/(a*u) ? Best regards, Timm

Dear WAsP Team, I'm studying Geophysics and Meteorology and currently i'm working at my Bachelor Thesis. One topic of the thesis is a survey of the connection between ambient turbulence and terrain complexity. In one chapter, i want to describe how the ambient turbulence is modelled by WEng 3.0. I don't have to know every little step. But i have to give an overview of the whole process with the main facts. So the first input is the Generalised Wind Climate(.lib file). With this information WEng predicts a wind flow over the turbine site, with the LINCOM model but in a slightly different form. But how does it works exactly? I know that the basic equations are the mass and momentum equations. Then there are lots of conversions until we get to the set of the linear equations, like in ris-r-900 page 13. Is the reason for these conversations to transform the nonlinear to linear equations? These equations are solved with a fourier transformation?! Do the solutions of these equations represent the predicted wind flow? Please correct me if there is anything wrong. With this results the WAT tool models the ambient turbulence TI_WEng? Which model is used? Is it the one from Mann 1994 (uniform gradient turbulence model) or from Kaimal 1972 (spectral and exponential coherencemodel) ? And how does these models work? I know these are a lot of questions, but it would be very nice if someone could help me. Best regards Timm