Numerical study and LiDAR based validation of the wind field in urban sites

Abstract

Within the project "Windy Cities"the economic use of small wind turbines in urban areas is investigated in Tübingen, Germany. This test-site contains complex terrain, forested areas and various types of buildings making the local wind field more turbulent and complex. To avoid damages and reduced life times of small wind turbines caused by high turbulence a detailed prediction of the wind field is essential in the present study. This is done using CFD. The scope of this study is the validation of the setup including terrain and vegetation. For this, on-site planar wind field LiDAR data are utilized to define the inflow boundary condition for highly resolved Detached Eddy Simulations (DES) using ANSYS Fluent. The required preprocessing steps of the LiDAR data are explained in detail and their assumptions, which are made to interpolate the data onto the numerical inflow plane. Since the inflow region is covered by forested zones a forest model is introduced with a local tree height adaption based on Laser scan data. LiDAR data, which are measured further downstream, are used to validate the forest model. Simulations with and without the considered forest are compared to investigate the influence of the forested region.