三圆柱形相邻高层建筑间风场干扰的CFD模拟

CFD simulation of aerodynamic interference effects of three cylindrical tall buildings

以三圆柱体模拟相邻高层建筑群体,首先对风洞试验中的正三角形布置的三个圆柱绕流进行数值模拟,数值模拟结果与风洞试验结果符合良好,验证了数值模型的可靠性.然后以高雷诺数(1.6×107)下二维正三角形排列的三个圆柱作为高层建筑群的简化模型进行数值模拟,结果表明:当间距比较小时,后排并列两结构尾流宽窄不同,说明在实际结构中也存在偏流现象;后排并列的两结构的平均阻力系数随着间距比的增加而振荡变化,变化幅值逐渐减小并趋同于单体结构平均阻力系数;三个结构体的斯特劳哈尔数变化趋势与风洞试验结果相似,且随结构间距比增加逐渐趋同于单体结构,但三体结构斯特劳哈尔数趋同的临界间距比与风洞试验结果不同,显示临界间距比可能与雷诺数有关.

The group effect of tall buildings were modeled by three circular cylinders.Firstly,the wind tunnel tests of three parallel circular cylinders in equilateral-triangular arrangements were numerically simulated.The numerical results are in a good agreement with test results,which verified the feasibility of the numerical model.Then,the two dimensional model of three circular cylinders in equilateral-triangular arrangements was used as a simplified model for the simulation of flow around three tall buildings in the following studies.It is shown that in small spacing ratio,the wake behind two back parallel circular structures of the three is asymmetrical,and it is explained as the phenomenon of bistable flow around actual structures.With the increasing spacing ratios,the mean drag coefficients of three circular structures fluctuate,while the amplitude of fluctuation decreases,and tend to be the same with that of the single one.The changing tendency of Strouhal numbers of the three circular cylinders are the same as that of the experimental results.The values of the three circular structures approach to the same of that of the single circular cylinder with the increasing spacing ratios.It is found that the critical spacing ratio is different from the experimental ones,indicating that the critical spacing ratio may probably be affected by Reynolds numbers.