Numerical investigation of interference effects on the critical wind velocity of tall buildings

Abstract

The main aim of this study is to evaluate the upstream and downstream interference effect of two CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall buildings using Computational Fluid Dynamics (CFD). To that end, the Large Eddy Simulation (LES) turbulence model is employed for the three-dimensional simulations of turbulent wind flow with Reynolds numbers of 1.4×104<Re<8×104. The aerodynamic response of the principal building in different interference cases is investigated using mean and fluctuating coefficients of lift and drag forces, pressure distribution and Strouhal number. To better understand the involved physics, streamlines and vorticity contours are presented and their relationship with the aerodynamic results is interpreted. In addition, an isolated CAARC standard tall building is considered for comparison with interference cases and to validate our results compared to previous experimental and numerical studies. In contrast with the isolated case, in most of the interference cases, the shielding effect of the interfering building results in a lower mean drag coefficient of the principal building. Also, compared to the isolated building and, depending on the location of the interfering building, the fluctuating lift coefficient either increases or decreases. While the mean pressure coefficient at the windward surface is not significantly sensitive to the interference states, it is strongly influenced by the different states of the interference at the lateral and leeward surfaces. Also, the principal building’s Strouhal numbers for different interference states and different Reynolds numbers are calculated using spectral analysis of lift signals. It is then shown that Strouhal numbers are highly dependent on the location of the interfering building and are inversely related to the width of the wake region. Our results, furthermore, demonstrate that the aerodynamic parameters have little sensitivity to Reynolds number variations in the considered range. Finally, the critical wind velocity corresponding to the aeroelastic instabilities is estimated based on Strouhal numbers and it is shown that upstream interference cases, will increase the critical velocity of the wind, thereby reducing the likelihood of occurrence of aeroelastic instabilities.