Abstract
The presence of solitary trees in a flat terrain introduce heterogeneities, which modify the characteristics of the wind. Trees act like obstacles that extract energy from the mean flow and increase the turbulence of the wind. This has an impact on the momentum flux and thus is of particular interest in climate related studies. Furthermore, the wind-trees interaction is a topic of study also in applied research areas, like wind energy, where the estimation of wind resources and associated turbulence levels is necessary to describe accurately the wind conditions over an area. In the case of rough landscapes typical uncertainties in the estimation of the terrain roughness can result to 10% uncertainty in the annual energy production estimate [1]. In order to contribute to the understanding of the aforementioned topics a project called Single Tree was initiated in the Wind Energy Department of the Technical University of Denmark (DTU), with the objective to characterize the flow around a solitary tree. For the needs of this study a European Oak tree (Quercus robur), located on the shore of the Roskilde fjord in Denmark, was selected. Such a tree is commonly found in forests or solitarily in urban and rural environments in temperate regions. Using a commercial terrestrial laser scanner, the dimensions and the detailed geometry of the tree were measured (see Figure 1 and Figure 2, left) and two meteorological masts equipped with multiple in-situ sonic anemometers were used to provide reference measurements of the wind conditions. A phenomenon that describes the wind-trees interaction is the wake of a tree, since it is the result of the momentum extracted from the wind due to the presence of the tree, which acts as a porous obstacle with a complex geometry. This complex geometry creates challenges in the numerical prediction of wind-trees interactions and thus the generation of high quality experimental flow data is paramount. Such an investigation is feasible using three short-range WindScanners, which are mobile remote sensing instruments developed in the Wind Energy Department of DTU [2].
Info
Conference Abstract, 2018
UN SDG Classification
DK Main Research Area
Science/Technology
