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Abstract
An analytical model for the streamwise velocity spacetime correlations in turbulent flows is derived and applied to the special case of velocity fluctuations in large wind farms. The model is based on the KraichnanTennekes random sweeping hypothesis, capturing the decorrelation in time while including a mean wind velocity in the streamwise direction. In the resulting model, the streamwise velocity spacetime correlation is expressed as a convolution of the pure space correlation with an analytical temporal decorrelation kernel. Hence, the spatiotemporal structure of velocity fluctuations in wind farms can be derived from the spatial correlations only. We then explore the applicability of the model to predict spatiotemporal correlations in turbulent flows in wind farms. Comparisons of the model with data from a large eddy simulation of flow in a large, spatially periodic wind farm are performed, where needed model parameters such as spatial and temporal integral scales and spatial correlations are determined from the large eddy simulation. Good agreement is obtained between the model and large eddy simulation data showing that spatial data may be used to model the full spatiotemporal structure of fluctuations in wind farms.
Original language  English 

Pages (fromto)  474487 
Number of pages  14 
Journal  Wind energy 
Volume  21 
Issue number  7 
Early online date  12 Mar 2018 
DOIs  
Publication status  Published  1 Jul 2018 
Keywords
 Large eddy simulation
 Power output fluctuations
 Spacetime correlations
 Turbulent flows
 Wind farms
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 1 Oral presentation

Modeling spacetime correlations of velocity fluctuations in wind farms
Richard Johannes Antonius Maria Stevens (Speaker)
18 Nov 2011Activity: Talk or presentation › Oral presentation