RANS simulations of aerodynamic forces on a tall building under twisted winds considering horizontal homogeneity

Abstract

The direction of the approaching wind could be significantly affected by mechanical forces in the atmospheric boundary layer (ABL) such as local topography and the Coriolis effect. The variation of wind directions along with the height (i.e., twisted wind or veering wind) might significantly influence the aerodynamic forces acting on tall buildings. In this study, a set of inflow boundary conditions based on RANS (Reynolds Averaged Navier-Stokes Equations) simulations are developed to mimic the twisted wind field with special emphasis on the horizontal homogeneity. Moreover, the aerodynamic forces acting on a squared tall building are predicted based on the simulated twisted winds. The results reveal that the horizontal homogeneity of the inflow conditions for twisted winds at the ground surface is significantly improved by appropriate tuning of the turbulence dynamic viscosity in the MMK (Murakami-Mochida-Kondo) model. The twisted-wind-induced flow around the building and associated wind pressure distribution can be well mimicked based on the developed boundary conditions and application of the MMK turbulence model. The developed inflow boundary conditions have been extended to the SST k-ω model and the predicting aerodynamic forces on the squared tall building under twisted winds are in good correspondence with experimental measurements.