Cross-sectional imaging of refractive-index-matched liquid-granular flows

Ni, Wei-Jay; Capart, Hervé

doi:10.1007/s00348-015-2034-3

Cited by 19 publications

(16 citation statements)

References 33 publications

(68 reference statements)

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“…For each voxel swept by the laser, we can also determine the occupancy χ S , set to 1 if the voxel center is within a solid grain and 0 otherwise. The solid fraction or volumetric granular concentration can then be determined over a region of interest as the average

c_{S} = {\overset{χ}{true}}_{S}

(Drew, ; Ni & Capart, ). For the lateral scans, the laser plane is oriented parallel to the flow, scanned from side to side, and imaged by the camera from the left and from the right.…”

Section: Methodsmentioning

confidence: 99%

“…The solid particles can also be tracked, yielding granular velocity components u S , w S that are checked to agree with those acquired from the longitudinal scans. The algorithms used to perform these tasks are described in detail in Ni and Capart (). After scans are completed, we intercept the channel outflow over a brief timed interval to obtain direct estimates of the solid and liquid discharges Q S and Q L in the channel.…”

Section: Methodsmentioning

confidence: 99%

“…To overcome these limitations, we make bed load layers transparent by using solid and liquid materials of matched refractive index. We then scan a laser light sheet across the medium to record liquid and granular motions over a three‐dimensional volume and measure velocities and concentration using the imaging algorithms described in Ni and Capart (). Similar techniques have earlier been applied to laminar bed load (Allen & Kudrolli, ; Aussillous et al, ; Houssais et al, ) and other systems of hard or soft particles immersed in liquids (Dijksman et al, , ; Wiederseiner et al, ).…”

Section: Introductionmentioning

confidence: 93%

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Stresses and Drag in Turbulent Bed Load From Refractive Index‐Matched Experiments

Capart

2018

Geophysical Research Letters

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We report steady open‐channel flow experiments that resolve the internal dynamics of turbulent bed load layers at subgrain diameter resolution. Optical access is gained by using materials of matched refractive index, and a laser light sheet is scanned across the medium to capture both the solid and liquid motions over a 3‐D volume. The imaging measurements yield vertical profiles of granular concentration, solid and liquid mean velocity, and velocity fluctuation statistics including the granular temperature and the Reynolds stress. This makes it possible to determine all principal contributions to the momentum balance of each phase. In particular, experimental profiles are obtained for the stresses and interphase drag force. They are used to test constitutive relationships derived from kinetic theory, turbulence theory, and fluidization cell experiments.

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c_{S} = {\overset{χ}{true}}_{S}

(Drew, ; Ni & Capart, ). For the lateral scans, the laser plane is oriented parallel to the flow, scanned from side to side, and imaged by the camera from the left and from the right.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

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Stresses and Drag in Turbulent Bed Load From Refractive Index‐Matched Experiments

Capart

2018

Geophysical Research Letters

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“…In this study, we used the X-ray microtomography device of Laboratoire One of the advantages of this technique is that the spatial resolution can be isotropic, contrary to other scanning techniques, such as confocal microscopy, laser scanning or refractive index matched scanning [12,[26][27][28][29]. This allows to get information on the microstructure with the same accuracy in all planes.…”

Section: X-ray Microtomographymentioning

confidence: 99%

Imaging non-Brownian particle suspensions with X-ray tomography: Application to the microstructure of Newtonian and viscoplastic suspensions

Debœuf

Lenoir

Hautemayou

et al. 2018

Journal of Rheology

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“…The median diameter was d p = d 50 = 8 mm. A bimodal size distribution has been used because otherwise the beads arrange itself in structured parallel layers causing undesirable bias in the averaged porosity and velocity profiles (as observed by Ni & Capart (2015)).…”

Section: Setupmentioning

confidence: 99%

Modeling turbulent stream flows over rough permeable beds

Rousseau¹,

Pascal²,

Ancey³

2020

River Flow 2020

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In steep streams, turbulent flows run over coarse sediments that are similar in size to flow depth. Under these conditions, a significant part of the flow may seep through the permeable bed. Based on experimental data, this paper presents a model able to reproduce the vertical structure of flows over rough permeable beds in low relative submergence conditions. Experiments were performed on open-channel flows passing over tilted coarse-grained beds with slopes within the 0.5% -4% range. Fluid velocities were measured by Particle Image Velocimetry (PIV) and a technique called Refractive Index-Matched Scanning (RIMS), allowing the interior of the bed to be examined. By applying the double averaging methodology, porosity and mean velocity, as well as turbulent and dispersive stresses profiles were collected from the subsurface to the free surface. A turbulent boundary layer over the rough bed was observed while experiments were run at intermediate Reynolds numbers, i.e. Re = O(1000). Under these flow conditions, viscosity played a non-negligible role through the van Driest damping effect. Based on the Prandtl mixing length theory, we propose a model for the turbulent stress that takes into account the continuous porosity profile, damping and dispersive effects. Finally, we show a good agreement between the model and classic flow resistance laws employed for river studies. Our model contrasts with existing boundary-layer models which generally assume a discontinuous porosity profile at bed interface, whether the bed is permeable or impermeable.

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Cross-sectional imaging of refractive-index-matched liquid-granular flows

Cited by 19 publications

References 33 publications

Stresses and Drag in Turbulent Bed Load From Refractive Index‐Matched Experiments

Stresses and Drag in Turbulent Bed Load From Refractive Index‐Matched Experiments

Imaging non-Brownian particle suspensions with X-ray tomography: Application to the microstructure of Newtonian and viscoplastic suspensions

Modeling turbulent stream flows over rough permeable beds

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