The flow structure around circular cylinders is an interesting research topic. At the Institute for Aerodynamics and Flow Technology (DLR), cylindrical devices are investigated as passive stall control for helicopters. These so called Leading Edge Vortex Generators (LEVOGS) force the boundary layer to transition from laminar to turbulent. The Tubercle Engineering Group GmbH (TEG) in Munich is interested in the transferabil- ity of these devices for wind turbines to minimise abrasion due to dynamic stall. Simulations of these cylindrical devices are supposed to show how the boundary layer of a surface with wall mounted cylinders is affected. The benchmark publication of Pattenden et al. is the starting point of this thesis since it is the lowest aspect ratio for validation data found in literature. In their paper, the authors investigated the flow pattern around a wall mounted cylinder with height and diameter = 150 mm in a wind-channel with a free-stream velocity of 20 m/s and a Reynolds number of 200 000 with regard to the diameter. In their simulations, Pattenden et al. replicated this case and solved it using DES and LES simulations. Both simulation types had their advantages and disadvantages. In the simulations of this thesis, the findings of Pattenden et al. are used to develop an im- proved case set-up. RANS, DES, DDES and LES simulations are performed using different turbulence models, meshes and discretisation schemes. The RANS simulations are applied to examine the influence of boundary conditions and to provide a basis for comparing the DES results. According to Pattenden et. al, the further investigation of the DES model bears the greatest potential. However, the improvement of the different parameters of the DES simulation does not deliver the desired improvement of the results. Therefore, first investigations of improved LES simulations are introduced in this thesis but a detailed development was beyond the scope of this thesis. Regarding the purpose to investigate the flow structure over a wind turbine blade with wall mounted LEVOGS, it can be stated that it is not possible with the computational resources available today.     «

The flow structure around circular cylinders is an interesting research topic. At the Institute for Aerodynamics and Flow Technology (DLR), cylindrical devices are investigated as passive stall control for helicopters. These so called Leading Edge Vortex Generators (LEVOGS) force the boundary layer to transition from laminar to turbulent. The Tubercle Engineering Group GmbH (TEG) in Munich is interested in the transferabil- ity of these devices for wind turbines to minimise abrasion due to dynam...     »