| Summary: | The group influence of three high-rise buildings was modelled by considering the buildings as three circular cylinders. The typical wind tunnel tests of flow around one circular cylinder at a Reynolds number of 3900 and around three circular cylinders in equilateral-triangular arrangements were numerically simulated. The numerical results were in good agreement with wind tunnel test results, demonstrating the feasibility of the numerical model. In the subsequent studies, a two-dimensional model of three circular cylinders in equilateral-triangular arrangements was used as a simplified model for the simulation of flow around the three high-rise buildings. The result showed that at a small spacing ratio, the wake behind two parallel structures downstream of the three was asymmetrical; this result was explained by the phenomenon of bistable flow around practical structures. With an increase in spacing ratios, the asymmetrical wakes of the two parallel structures disappeared, and the range of the critical spacing ratio of bistable flow was identified. The changing tendency of the drag coefficients and the lift coefficients of two parallel structures downstream was not a simple decrease, and was more complicated than that of two side-by-side cylinders. At small spacing ratios, the bistable flow generated an across-wind force.
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