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Flow patterns and free-surface dynamics in hydraulic jump on pebbled rough bed
Proceedings of the Institution of Civil Engineers - Water Management ( IF 1.1 ) Pub Date : 2021-04-26 , DOI: 10.1680/jwama.20.00040
Farhad Bahmanpouri 1 , Carlo Gualtieri 2 , Hubert Chanson 3
Affiliation  

Some basic characteristics of a classic hydraulic jump flow over a pebbled rough bed, as well as on a smooth bed as a reference, are presented in this experimental study. For the experiments, an inflow Froude number Fr1 from 1.54 to 4.94 and inflow Reynolds number Re1 from 42 000 to 230 000 were considered. Visual observations and measurements suggested some differences between the formation of a hydraulic jump on rough and smooth bed configurations, including different air entrainment processes, larger vortical structures in the roller length and stronger backward flow in the upper layer. Furthermore, the jump roller and aerated flow lengths were shorter on a pebbled rough bed than on a smooth bed, while the dimensionless advection velocity of large vortices was the same for both bed types. The instantaneous jump toe perimeter showed the largest variation at the largest Fr1 and was generally larger on rough bed than on smooth bed. Larger oscillations of the free-surface profile were observed on smooth bed, highlighting that roughness resulted in smaller free-surface oscillations, suggesting the higher rate of energy dissipation.

中文翻译:

卵石粗糙床上水跃的流动模式和自由表面动力学

本实验研究介绍了在鹅卵石粗糙床上以及作为参考的光滑床上的经典水力跳跃流的一些基本特征。对于实验,流入弗劳德数 Fr 1从 1.54 到 4.94 和流入雷诺数 Re 1考虑了 42 000 到 230 000。目视观察和测量表明,在粗糙床和光滑床配置上形成水跃之间存在一些差异,包括不同的空气夹带过程、辊长度中较大的涡流结构和上层中较强的回流。此外,在鹅卵石粗糙床上的跳跃辊和曝气流长度比在光滑床上短,而大涡流的无量纲平流速度对于两种床类型是相同的。瞬时跳趾周长在最大 Fr 1处变化最大并且在粗糙的床上通常比在光滑的床上大。在光滑床上观察到自由表面轮廓的较大振荡,突出表明粗糙度导致较小的自由表面振荡,表明能量耗散率较高。
更新日期:2021-04-26
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