Influence of Weak Bed-Load Transport on Mean Flow Characteristics over Immobile Smooth Bed Surface under Dynamic Equilibrium Flow Conditions

Malakar, Pritam; Datta, Akash; Das, Ratul

doi:10.1007/s11269-020-02702-5

Cited by 2 publications

(1 citation statement)

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“…The mean velocity (U), flow Reynolds number (Re), flow Froude number (F) and bed-load transport rate (gb) varied in the following ranges: 0.48 m/s ≤ U ≤ 0.67 m/s, 1.8 × 10 5 ≤ Re ≤ 3.4 × 10 5 , 0.44 ≤ F ≤ 0.53 and 1.03 × 10 -2 kg/(ms) ≤ gb ≤ 3.28 × 10 -2 kg/(ms). The experimental details can be found in Malakar et al (2020). In order to achieve dynamic equilibrium conditions, the sediment transport rate was initially quantified by collecting the transported grains in a sediment collector installed at downstream.…”

Section: Methodsmentioning

confidence: 99%

Relative role of sediment entrainments on log-law parameters of longitudinal velocity distributions in mobile bed flows

Malakar

Das

2021

Journal of Hydrology and Hydromechanics

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In alluvial channel, the non-cohesive bed particles are frequently accelerated by the flows and there has been an inconclusive debate on the deviations of logarithmic law parameters that demonstrate the velocity distributions in flows. Present study aims to elucidate the current knowledge of overwhelming theoretical and experimental evidences in this regard within the scope of near-bed turbulent flow characteristics. The study was conducted in two folds collecting instantaneous velocity of flow over a rigid sand bed under clear water flow conditions and compared to those over mobile sand beds under equilibrium bed-load. Results corroborated additional support to confirm the upward shifting of zero-velocity level in mobile bed flows. Most importantly, the conventional value of von Kármán coefficient significantly deviates in mobile bed flows compared to those in rigid sand bed. Also, the frictional velocity obtained from the bed slope consistently differs to those obtained from the Reynolds shear stress (RSS) distributions owing to transfer of stress aliquot to the bed particles. The mechanism is well demonstrated with the energy-momentum transfer within the framework of energy budget concept which shows near-bed negative pressure energy diffusion rates with increasing turbulence production in mobile bed flows.

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Section: Methodsmentioning

confidence: 99%