PIV-based pressure estimation in the canopy of urban-like roughness
PIV-based pressure estimation in the canopy of urban-like roughness
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DOI：
10.1007/s00348-020-2904-1
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发表时间：
2020-02
影响因子：
2.4
通讯作者：
M. A. Ferreira;B. Ganapathisubramani
中科院分区：
文献类型：
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作者：
M. A. Ferreira;B. Ganapathisubramani
摘要本文利用PIV测量的面内速度数据，通过二维RANS和二维TH方法，对两个不同高度分布的长方体交错排列的座舱盖上和座舱盖内的压力场进行了估算。这种方法的可行性进行检查，首先比较平均阻力剖面对报告的风洞测量，进行了类似的试验条件和数值模拟（LES和DNS）。表面阻力从粗糙度元素周围最近的数据点外推。第二，摩擦速度和零平面位移高度的估计，通过对每个单独障碍物上的轴向压力差进行积分获得，假设它是展向均匀的。这些进行了比较，对直接测量的壁面剪应力从浮动元件平衡和压力抽头立方体，以及对间接方法的估计。除了平均压力图，压力场的快照是通过2D-TH获得的，基于泰勒假设，用于计算立方体表面上的压力波动的RMS。计算结果表明，2D-RANS和2D-TH的计算性能良好，能够提供平均压力分布和边界层流动参数的合理估计值，优于依赖于平衡假设的间接方法，而平衡假设往往无法得到验证。
AbstractIn-plane velocity measurements from PIV are used to estimate the pressure field above and within the canopy of two staggered arrays of cuboids, with distinct height distributions, via 2D-RANS and 2D-TH. The viability of this approach is examined by first comparing the mean drag profiles against reported wind-tunnel measurements that were carried out under similar test conditions and numerical simulations (LES and DNS). The surface drag is extrapolated from the nearest data point surrounding the roughness elements. Second, estimates of the friction velocityand the zero-plane displacement heightare obtained by integrating the axial pressure difference across each individual obstacle, assuming it is spanwise uniform. These are compared against direct measurements of the wall-shear stress from a floating-element balance and a pressure-tapped cube, as well as against estimates from indirect methods. In addition to mean pressure maps, snapshots of the pressure field are obtained via 2D-TH, based on Taylor’s Hypothesis, which are used to compute the RMS of the pressure fluctuations on the surface of a cube. The results indicate that 2D-RANS and 2D-TH perform adequately, providing reasonable estimates of the mean pressure distribution and of the boundary-layer flow parameters, outperforming indirect methods which rely on equilibrium assumptions that are often not verified.Graphic abstract