RECOMMENDED PRACTICES WHEN ANALYZING WIND FLOW NEAR A FOREST EDGE WITH WASP

摘要

In recent years, wind prediction models have been used more and more frequently to characterize wind resource. The main advantage of these models is that they require the installation of a minimum number of costly measurement masts. However, they are very sensitive to the position of the measurement masts, especially in the presence of forest. This paper analyzes wind flow predictions obtained from WAsP using different reference masts near a forest edge. The solution dependency on the mast position was analyzed, and results were compared to numerical predictions from a Computational Fluid Dynamics (CFD) model. The model was validated using field measurements from two different authors. The CFD model used a porous media approach combined with a modified k-ε turbulence model to simulate momentum losses and turbulence generation within the forest. The momentum losses were represented by a drag coefficient and a leaf area density. In WAsP, the forest was represented by a roughness length and a displacement height that was calculated using the forest height. Two wind directions were analyzed: wind flow entering and wind flow leaving the forest. Results indicated that, to obtain acceptable results from WAsP, the measurement mast should be located outside the forest. If this is not possible, it should be located at an altitude greater than at least five times the forest height.