Hydrodynamics and turbulence of free-surface flow over a backward-facing step
Hydrodynamics and turbulence of free-surface flow over a backward-facing step
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DOI：
10.1080/00221686.2023.2239751
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发表时间：
2023-09
影响因子：
2.3
通讯作者：
Qianyu Luo;T. Stoesser;R. Jalalabadi;Zhihua Xie
中科院分区：
文献类型：
--
作者：
Qianyu Luo;T. Stoesser;R. Jalalabadi;Zhihua Xie
本文采用三个大涡模拟方法研究了淹没对后台阶下游水流的湍流、水动力和水面变形的影响。水面的变形、回流区的范围以及剪切层的强度是相对淹没的函数。台阶下游的所有流动都表现出较高的湍流剪切应力水平，并含有大量的湍流动能。瞬时流动的特点是紧挨在台阶后面的滚子和从剪切层脱落的马蹄形涡流，后者被平流输送到水面，在那里它们引起变形。研究表明，这些涡流可以起源于沿着分裂流线的任何位置;然而，它们越接近其起源的平均附着位置，所包含的能量就越多。
Three large-eddy simulations of open channel flow over a backward-facing step are performed to investigate the effect of submergence on the turbulence, hydrodynamics, and water surface deformation downstream of the step. The deformation of the water surface, the extent of the recirculation zone as well as the strength of the shear layer are a function of relative submergence. All flows downstream of the step exhibit elevated levels of turbulent shear stress and contain significant amounts of turbulent kinetic energy. The instantaneous flow features rollers immediately behind the step and horseshoe-shaped vortices shed from the shear layer, the latter being advected towards the water surface where they cause deformations. It is shown that these vortices can originate from any location along the dividing streamline; however, they contain more energy the closer to the mean attachment location they originate.