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Abstract <p>Understanding the dynamics of turbulent flow over bimodal sediment beds is essential for predicting sediment transport and channel morphology in natural and engineered water systems. Unlike previous studies that primarily focus on longitudinal turbulence behaviour, the present study elucidates the lateral heterogeneity of turbulence over bimodal sediment beds. A three-dimensional Acoustic Doppler Velocimeter was used to capture velocity fluctuations at multiple lateral subsections. The data were processed using quadrant analysis, evaluation of turbulent kinetic energy flux, spectral analysis, and dissipation rate estimation. Results indicate that sediment roughness and lateral bed heterogeneity significantly influence turbulence structure. Elevated roughness correlates with increased dissipation rates and reduced integral length scales. Ejection and sweep events (Q2 and Q4) dominate near-bed turbulence, facilitating sediment entrainment and transport. Lateral variation in turbulent characteristics was found to be substantial, demonstrating the importance of three-dimensional analysis in sediment-laden flows. These insights can improve the design of sediment control strategies and river restoration measures in bimodal sediment environments.</p> Research highlights <p><UnorderedList Mark="Bullet"> <ItemContent> <p>Bed roughness controls turbulence strength and sediment entrainment patterns.</p> </ItemContent> <ItemContent> <p>Central channel zones show peak turbulence and enhanced erosive activity.</p> </ItemContent> <ItemContent> <p>Coarse particles amplify local turbulence, creating micro-scale scour pits.</p> </ItemContent> <ItemContent> <p>Lateral heterogeneity alters flow coherence and sediment sorting efficiency.</p> </ItemContent> <ItemContent> <p>Integral scales shrink as roughness grows, marking fine-scale eddy breakup.</p> </ItemContent> </UnorderedList></p>

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Characterization of high-order turbulence in bimodal sediment beds in open channel flow

  • 期刊论文

  • 发表日期：

    2026年3月19日

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  • Aryalaxmi Priyadarshini,
  • Nityabinod Sundar Ray,
  • Vikas Kumar Das,
  • Kishanjit Kumar Khatua

摘要

Abstract

Understanding the dynamics of turbulent flow over bimodal sediment beds is essential for predicting sediment transport and channel morphology in natural and engineered water systems. Unlike previous studies that primarily focus on longitudinal turbulence behaviour, the present study elucidates the lateral heterogeneity of turbulence over bimodal sediment beds. A three-dimensional Acoustic Doppler Velocimeter was used to capture velocity fluctuations at multiple lateral subsections. The data were processed using quadrant analysis, evaluation of turbulent kinetic energy flux, spectral analysis, and dissipation rate estimation. Results indicate that sediment roughness and lateral bed heterogeneity significantly influence turbulence structure. Elevated roughness correlates with increased dissipation rates and reduced integral length scales. Ejection and sweep events (Q2 and Q4) dominate near-bed turbulence, facilitating sediment entrainment and transport. Lateral variation in turbulent characteristics was found to be substantial, demonstrating the importance of three-dimensional analysis in sediment-laden flows. These insights can improve the design of sediment control strategies and river restoration measures in bimodal sediment environments.

Research highlights

Bed roughness controls turbulence strength and sediment entrainment patterns.

Central channel zones show peak turbulence and enhanced erosive activity.

Coarse particles amplify local turbulence, creating micro-scale scour pits.

Lateral heterogeneity alters flow coherence and sediment sorting efficiency.

Integral scales shrink as roughness grows, marking fine-scale eddy breakup.