Meandering of instantaneous large-scale structures in open-channel flow over longitudinal ridges
Meandering of instantaneous large-scale structures in open-channel flow over longitudinal ridges
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DOI：
10.1007/s10652-023-09934-0
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发表时间：
2023-08
影响因子：
2.2
通讯作者：
Qian Luo;T. Stoesser;S. Cameron;V. Nikora;A. Zampiron;W. Patella
中科院分区：
文献类型：
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作者：
Qian Luo;T. Stoesser;S. Cameron;V. Nikora;A. Zampiron;W. Patella
给出了两个代表性展向间距下展向异质表面脊上的明渠流的大涡模拟结果。考虑了具有流向矩形脊的光滑河床上中等弗劳德数和雷诺数的流动。脊间距对流动具有深远的影响：在小间距时，出现相对较小的次生细胞，而在大脊间距时，次生细胞占据整个流动深度。瞬时流动具有二次流动不稳定性和交替的低动量区域和高动量区域的蜿蜒特征。对于两个脊间距，瞬时大范围运动的曲折的准周期性质被可视化和量化。尽管时间平均顺时针和逆时针二次电流单元关于脊轴对称，但它们在蜿蜒周期内表现出尺寸的准周期性增加和减小以及空间的横向和垂直运动。
The results of large-eddy simulations of open-channel flows over spanwise heterogeneous surface ridges at two representative spanwise spacings are presented. Flows at moderate Froude and Reynolds numbers over smooth channel beds with streamwise-orientated rectangular ridges are considered. The ridge spacing has a profound effect on the flow: at small spacing relatively small secondary cells occur, whilst at large ridge spacing secondary cells occupy the entire flow depth. The instantaneous flow features secondary flow instabilities and the meandering of alternating low- and high-momentum regions. The quasi-periodical nature of the meandering of the instantaneous large-scale motion is visualised and quantified for both ridge spacings. Although time-averaged clockwise and counter-clockwise secondary current cells are symmetrical about the ridge-axis, they exhibit quasi-periodical increase and decrease in size as well as lateral and vertical movement in space over the meandering period.