Numerical and experimental investigation of flow field around high-rise buildings

The external flow around a bluff body shows a complex, time-dependent, vortical and turbulent behavior. According to the shape of the object and the wind speed and direction, pressure differences occur on the surfaces of the body. In this thesis study, flow around high-rise buildings are investigated numerically and experimentally. Steady-state Computational Fluid Dynamics (CFD) simulations are performed by using unstructured grids and by solving Reynolds-Averaged Navier-Stokes equations. First, CFD simulations of flow around a wall-mounted cube are performed as a validation test case by using different grids, different turbulence models and different boundary conditions and the results are compared with the other experimental and numerical studies in the literature. Then, by choosing the turbulence model and boundary conditions which give the best results in these simulations, the flow around a high-rise building model is investigated. CFD simulations around a 20 cm x 15 cm x 50 cm high rise building model are performed for three different inlet velocity profiles (empty tunnel and tunnel with the roughness elements used to have atmospheric boundary layers for B and C exposure categories) and for two different wind angles (0° and 30°). In addition, for the same conditions, the experiments are performed in the Ankara Wind Tunnel for the high-rise building model that was built during this study. The mean surface pressure measurements by using pressure taps located on the front, top, rear and side surfaces of the building model and the velocity measurements by using hot-wire velocimetry in the wake of the building model are done. The computational results are compared with the experiments. Although there are differences in the results obtained, similar trends are obtained with the experiments. Finally, as examples for flows around complex shaped real buildings and building grups, the CFD simülations for the TOBB ETU Campus Buildings and TOBB ETU Student Guest House Buildings are performed and discussed.