Comparison of Speed-Up Over Hills Derived from Wind-Tunnel Experiments, Wind-Loading Standards, and Numerical Modelling
Comparison of Speed-Up Over Hills Derived from Wind-Tunnel Experiments, Wind-Loading Standards, and Numerical Modelling
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DOI：
10.1007/s10546-018-0350-x
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发表时间：
2018-03
影响因子：
4.3
通讯作者：
A. A. Safaei Pirooz-A.;R. Flay
中科院分区：
文献类型：
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作者：
A. A. Safaei Pirooz-A.;R. Flay
我们通过与分别在 1:500 标称比例和全比例下进行的风洞测量和数值预测进行比较，评估了几种风荷载标准中提供的加速的准确性。使用雷诺平均纳维-斯托克斯方法以及压力驱动的大气边界层和三种不同的湍流模型对二维和三维钟形山上的气流进行数值模拟。详细研究了网格尺寸对加速和流动分离的影响，以及数值模拟中由此产生的不确定性。加速比、尾流区域大小和位置的数值预测与大涡模拟和风洞结果吻合良好。数值结果表明，与大涡模拟相比，能够以相当少的计算时间准确地预测山上的气流。对三维山丘的数值模拟表明，由于三维山丘周围存在二次流，与二维山丘上的流动相比，加速和尾流区域显着减小。对不同的山坡和形状进行数值模拟，以研究山坡轮廓对加速的影响。与更尖的山峰相比，平顶山在山顶至大约一半山高的高度处的加速比较低，对此没有一个标准给出完全令人满意的加速值。总体而言，最新版本的加拿大国家建筑规范以及澳大利亚和新西兰标准给出了孤立山丘风速的最佳预测。
We evaluate the accuracy of the speed-up provided in several wind-loading standards by comparison with wind-tunnel measurements and numerical predictions, which are carried out at a nominal scale of 1:500 and full-scale, respectively. Airflow over two- and three-dimensional bell-shaped hills is numerically modelled using the Reynolds-averaged Navier–Stokes method with a pressure-driven atmospheric boundary layer and three different turbulence models. Investigated in detail are the effects of grid size on the speed-up and flow separation, as well as the resulting uncertainties in the numerical simulations. Good agreement is obtained between the numerical prediction of speed-up, as well as the wake region size and location, with that according to large-eddy simulations and the wind-tunnel results. The numerical results demonstrate the ability to predict the airflow over a hill with good accuracy with considerably less computational time than for large-eddy simulation. Numerical simulations for a three-dimensional hill show that the speed-up and the wake region decrease significantly when compared with the flow over two-dimensional hills due to the secondary flow around three-dimensional hills. Different hill slopes and shapes are simulated numerically to investigate the effect of hill profile on the speed-up. In comparison with more peaked hill crests, flat-topped hills have a lower speed-up at the crest up to heights of about half the hill height, for which none of the standards gives entirely satisfactory values of speed-up. Overall, the latest versions of the National Building Code of Canada and the Australian and New Zealand Standard give the best predictions of wind speed over isolated hills.