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<p>This study investigates the structural responses of shear layers and wall regions to three-dimensional obstacles of varying heights in continuous-inflow density currents. A custom-designed particle image velocimetry (PIV) system was employed to capture quasi-three-dimensional flow structures and reduce the inter-run variability inherent in traditional multi-section measurements. An optimized two-stage diffuser was used to ensure uniform spanwise inflow and prevent lateral momentum errors. This configuration enabled separate examination of plumes and underflows, revealing distinct dynamic behaviors. Results show two distinct response regimes. Plumes, consisting solely of a shear layer, consistently responded via efficient lateral bypassing, a mechanism that remained dominant even for obstacles in the low-profile regime where overtopping was easier. In contrast, underflows, featuring a wall region, were consistently dominated by upstream blockage and vertical deflection, with lateral bypassing remaining suppressed even for obstacles that created the most substantial lateral pressure gradients in the protruding case. Flow thickness analysis corroborates these distinct patterns. In the plume cases, obstacles force the central flow to bypass laterally, thinning the downstream layer and leading to a thinner and faster layer downstream of the obstacle. Underflows, however, exhibit increased thickness near the centerline due to upward fluid displacement from the wall region, with minimal spanwise redistribution. Turbulence intensity patterns also underscore these differences: plumes display peaks in areas of lateral flow diversion and downstream convergence, whereas underflows show high turbulence where upward-deflected wall region flow enters the shear layer.</p>

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Experimental investigation of shear layer and wall region responses to three-dimensional obstacles in steady density currents

  • 期刊论文

  • 发表日期：

    2026年6月20日

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  • Jingyao Chen,
  • Yanan Chen,
  • Benjamin Kneller,
  • Dongrui Han,
  • Eckart Meiburg,
  • Zhiguo He

摘要

This study investigates the structural responses of shear layers and wall regions to three-dimensional obstacles of varying heights in continuous-inflow density currents. A custom-designed particle image velocimetry (PIV) system was employed to capture quasi-three-dimensional flow structures and reduce the inter-run variability inherent in traditional multi-section measurements. An optimized two-stage diffuser was used to ensure uniform spanwise inflow and prevent lateral momentum errors. This configuration enabled separate examination of plumes and underflows, revealing distinct dynamic behaviors. Results show two distinct response regimes. Plumes, consisting solely of a shear layer, consistently responded via efficient lateral bypassing, a mechanism that remained dominant even for obstacles in the low-profile regime where overtopping was easier. In contrast, underflows, featuring a wall region, were consistently dominated by upstream blockage and vertical deflection, with lateral bypassing remaining suppressed even for obstacles that created the most substantial lateral pressure gradients in the protruding case. Flow thickness analysis corroborates these distinct patterns. In the plume cases, obstacles force the central flow to bypass laterally, thinning the downstream layer and leading to a thinner and faster layer downstream of the obstacle. Underflows, however, exhibit increased thickness near the centerline due to upward fluid displacement from the wall region, with minimal spanwise redistribution. Turbulence intensity patterns also underscore these differences: plumes display peaks in areas of lateral flow diversion and downstream convergence, whereas underflows show high turbulence where upward-deflected wall region flow enters the shear layer.