Externally generated turbulence by a vertically oscillating grid plate and its impact on sediment transport rate

Ojha, Satya P.; Mazumder, B. S.; Carstensen, Stefan; Fredsøe, Jørgen

doi:10.1080/21664250.2019.1619251

Cited by 3 publications

(3 citation statements)

References 34 publications

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“…Besides the microscopic particle properties, other factors that may also play important roles in the variation of the transport relation include the presence of external agitation (N. Cheng et al., 2020; Ojha et al., 2019; Sumer et al., 2003) and vegetation (Vargas‐Luna et al., 2015; C. Liu et al., 2021). It should also be noted that here we have only considered the case of simple channel geometry, whereas in actual riverbeds there are a number of channel morphologic features we have not considered that can make a difference, including bedforms (Parker, 1978) and the ratio of grain diameter to flow depth, especially if boulders are present that are not fully submerged (Venditti, 2013; Venditti et al., 2017; Yager et al., 2007).…”

Section: Discussionmentioning

confidence: 99%

Section: What Is (Not) Responsible For the Variability In The Observe...mentioning

confidence: 99%

“…We use the Discrete Element Method‐Lattice Boltzmann Method (DEM‐LBM) simulation data to derive continuum models of sediment transport that apply to a range of flow conditions and sediment characteristics. For simplicity, we will limit our investigation to the bedload sediment transport of mono‐disperse particles without considering vegetation (C. Liu et al., 2021; Vargas‐Luna et al., 2015), external agitation of the turbulence (N. Cheng et al., 2020; Ojha et al., 2019; Sumer et al., 2003), or channel morphology that is known to influence the transport relation, such as bedform patterns (Venditti, 2013; Venditti et al., 2017) or the presence of large (possibly not fully submerged) boulders (Yager et al., 2007).…”

Section: Bedload Transport Of Spherical Grainsmentioning

confidence: 99%

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Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

et al. 2022

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Bedload sediment transport is ubiquitous in shaping natural and engineered landscapes, but the variability in the relation between sediment flux and driving factors is not well understood. At a given Shields number, the observed dimensionless transport rate can vary over a range in controlled systems and up to several orders of magnitude in natural streams. Here, we (a) experimentally validate a resolved fluid‐grain numerical scheme (Lattice Boltzmann Method‐Discrete Element Method or DEM‐LBM), and use it to (b) explore the parameter space controlling sediment transport in simple systems. Wide wall‐free simulations show the dimensionless transport rate is not influenced by the slope, fluid depth, mean particle size, particle surface friction, or grain‐grain damping for gentle slopes (0.01–0.03) at a medium to high fixed Shields number. (c) Examination of small‐scale fluid‐grain interactions shows fluid torque is non‐negligible for the entrainment and sediment transport near the threshold. And (d) the simulations guide the formulation of continuum models for the transport process. We present an upscaled two‐phase continuum model for grains in a turbulent fluid and validate it against bedload transport DEM‐LBM simulations. To model the creeping granular flow under the bed surface, we use an extension of the Nonlocal Granular Fluidity model, which was previously shown to account for flow cooperativity from grain‐size‐effects in dry media. The model accurately predicts the exponentially decaying velocity profile deeper into the bed.

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Section: Discussionmentioning

confidence: 99%

Section: What Is (Not) Responsible For the Variability In The Observe...mentioning

confidence: 99%

Section: Bedload Transport Of Spherical Grainsmentioning

confidence: 99%

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Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

et al. 2022

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Flow structure and bottom friction of the nonlinear turbulent boundary layer under stormy waves

Xie

Zhang

et al. 2021

Coastal Engineering

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Higher-Order Turbulence Around Different Circular Cylinders Using Particle Image Velocimetry

Misuriya

Eldho

Mazumder

2021

Journal of Fluids Engineering

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Wakes and higher-order turbulence around circular cylinder of different diameters are investigated using particle image velocimetry measurements. The cylinder Reynolds number (Red) is defined by the depth averaged velocity, cylinder diameter and kinematic viscosity. The influence of Red on third-order moment of velocity fluctuations, turbulent kinetic energy (TKE) flux, TKE budget and turbulent length scales are presented. The intermittency factor and quadrant analysis around the cylinders are discussed for Red values ranging from 12,600 to 21,000. Intermittency factor increased with Red. Red effect modulated the energy budget mainly near free surface upstream and near bed downstream. Stream-wise and transverse TKE fluxes decreased significantly with Red, but not the vertical flux. Stream wise skewness changed sign from positive to negative with a certain critical distance on downstream, while vertical skewness showed reversed with Red. Negative stream-wise skewness and positive vertical skewness indicate the occurrence of ejection events. Production and dissipation rates increased with Red on the downstream, whereas opposite trend was observed for dissipation on the upstream. Increase of Red led to increase in Kolmogorov length-scale much higher on the upstream than downstream, whereas it showed depleting effect on Taylor's length-scale on upstream and increasing effect on the downstream. Ejection and sweep events were more prominent in the downstream near the cylinder than upstream with higher values of shear stress on the downstream. The sum of shear stress contributions of all quadrant events increased consistently with increase in Red near the cylinder.

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Externally generated turbulence by a vertically oscillating grid plate and its impact on sediment transport rate

Cited by 3 publications

References 34 publications

Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

Fluid‐Driven Transport of Round Sediment Particles: From Discrete Simulations to Continuum Modeling

Flow structure and bottom friction of the nonlinear turbulent boundary layer under stormy waves

Higher-Order Turbulence Around Different Circular Cylinders Using Particle Image Velocimetry

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