Particle–wall collisions in a viscous fluid

Joseph, G. G.; Zenit, Roberto; Hunt, M. L.; Rosenwinkel, A. M.

doi:10.1017/s0022112001003470

Cited by 330 publications

(324 citation statements)

References 16 publications

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“…The particle decelerates before it rebounds. This deceleration prior to impact was also observed in the experiments of Joseph et al (2001) and the simulations of Ardekani & Rangel (2008). As the gap decreases to less than δ ss , the elastic force stops the approach of the particle.…”

Section: Particle Velocitysupporting

confidence: 67%

“…As a sphere approaches the wall, the hydrodynamic pressure increases in the fluid layer between the two solid surfaces; with the increased pressure, the surfaces deform and collision happens either through the layer of fluid between the surfaces or between the roughness elements (see Davis et al 1986;Barnocky & Davis 1989;Joseph et al 2001). In addition as the fluid is compressed, its density and viscosity may increases, which may further limit the approach of the surfaces.…”

Section: Elastic Forcementioning

confidence: 99%

“…The later work by Davis, Rager & Good (2002) also used a thin layer of fluid but the investigators measured the impact and rebound velocity to determine the effective coefficient of restitution. In contrast, Joseph et al (2001) measured the approach and rebound of a fully immersed collision between a particle suspended as a pendulum and a wall to determine the coefficient of restitution as a function of Stokes number. From their experimental measurements they showed that below a Stokes number of approximately 10, no rebound of the particle occurs.…”

Section: Introductionmentioning

confidence: 99%

“…The dry coefficient of restitution depends on the properties of the solid phases and impact speed. The study by Joseph et al (2001) measured e d of around 0.90 for glass, steel and Nylon particles colliding against a Lucite wall with impact speeds from 40 to 360 mm s −1 ; e d was higher (approximately 0.97) when these particles impacted a harder glass or Zerodur surface. The dependence of the coefficient of restitution on the Stokes number was also presented in the work by Gondret, Lance & Petit (2002); in this study, the authors measured the normal trajectory of the particle over multiple bounces.…”

Section: Introductionmentioning

confidence: 99%

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A contact model for normal immersed collisions between a particle and a wall

Hunt

Colonius

2011

J. Fluid Mech.

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The incompressible Navier-Stokes equations are solved numerically to predict the coupled motion of a falling particle and the surrounding fluid as the particle impacts and rebounds from a planar wall. The method is validated by comparing the numerical simulations of a settling sphere with experimental measurements of the sphere trajectory and the accompanying flow field. The normal collision process is then studied for a range of impact Stokes numbers. A contact model of the liquid-solid interaction and elastic effect is developed that incorporates the elasticity of the solids to permit the rebound trajectory to be simulated accurately. The contact model is applied when the particle is sufficiently close to the wall that it becomes difficult to resolve the thin lubrication layer. The model is calibrated with new measurements of the particle trajectories and reproduces the observed coefficient of restitution over a range of impact Stokes numbers from 1 to 1000.

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Section: Particle Velocitysupporting

confidence: 67%

Section: Elastic Forcementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A contact model for normal immersed collisions between a particle and a wall

Hunt

Colonius

2011

J. Fluid Mech.

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“…Note, however, that the asymptotic expansions have been derived for a perfectly smooth and inelastic sphere/wall and are based on the assumption that the Stokes equations still hold for the flow in the intervening film when → 0. From experiments it is known that surface roughness elements of the sphere/wall cause actual sphere-sphere/wall contact when the gap width ( R) is of the order of the typical size of the surface roughness elements (Joseph et al 2006). This will hamper further drainage of the intervening film and the drainage process will eventually stop when many roughness elements have made contact with each other.…”

Section: Appendix Details On Numerical Methodsmentioning

confidence: 99%

Active suspensions in thin films: nutrient uptake and swimmer motion

et al. 2013

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A numerical study of swimming particle motion and nutrient transport is conducted for a semidilute to dense suspension in a thin film. The steady squirmer model is used to represent the motion of living cells in suspension with the nutrient uptake by swimming particles modelled using a first-order kinetic equation representing the absorption process that occurs locally at the particle surface. An analysis of the dynamics of the neutral squirmers inside the film shows that the vertical motion is reduced significantly. The mean nutrient uptake for both isolated and populations of swimmers decreases for increasing swimming speeds when nutrient advection becomes relevant as less time is left for the nutrient to diffuse to the surface. This finding is in contrast to the case where the uptake is modelled by imposing a constant nutrient concentration at the cell surface and the mass flux results to be an increasing monotonic function of the swimming speed. In comparison to non-motile particles, the cell motion has a negligible influence on nutrient uptake at lower particle absorption rates since the process is rate limited. At higher absorption rates, the swimming motion results in a large increase in the nutrient uptake that is attributed to the movement of particles and increased mixing in the fluid. As the volume fraction of swimming particles increases, the squirmers consume slightly less nutrients and require more power for the same swimming motion. Despite this increase in energy consumption, the results clearly demonstrate that the gain in nutrient uptake make swimming a winning strategy for micro-organism survival also in relatively dense suspensions.

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Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

Heyman

Bohorquez

Ancey

2016

J. Geophys. Res. Earth Surf.

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International audienceIn gravel bed rivers, bed load transport exhibits considerable variability in time and space. Recently, stochastic bed load transport theories have been developed to address the mechanisms and effects of bed load transport fluctuations. Stochastic models involve parameters such as particle diffusivity, entrainment, and deposition rates. The lack of hard information on how these parameters vary with flow conditions is a clear impediment to their application to real-world scenarios. In this paper, we determined the closure equations for the above parameters from laboratory experiments. We focused on shallow supercritical flow on a sloping mobile bed in straight channels, a setting that was representative of flow conditions in mountain rivers. Experiments were run at low sediment transport rates under steady nonuniform flow conditions (i.e., the water discharge was kept constant, but bed forms developed and migrated upstream, making flow nonuniform). Using image processing, we reconstructed particle paths to deduce the particle velocity and its probability distribution, particle diffusivity, and rates of deposition and entrainment. We found that on average, particle acceleration, velocity, and deposition rate were responsive to local flow conditions, whereas entrainment rate depended strongly on local bed activity. Particle diffusivity varied linearly with the depth-averaged flow velocity. The empirical probability distribution of particle velocity was well approximated by a Gaussian distribution when all particle positions were considered together. In contrast, the particles located in close vicinity to the bed had exponentially distributed velocities. Our experimental results provide closure equations for stochastic or deterministic bed load transport models. ©2016. American Geophysical Union. All Rights Reserved

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Particle–wall collisions in a viscous fluid

Cited by 330 publications

References 16 publications

A contact model for normal immersed collisions between a particle and a wall

A contact model for normal immersed collisions between a particle and a wall

Active suspensions in thin films: nutrient uptake and swimmer motion

Entrainment, motion, and deposition of coarse particles transported by water over a sloping mobile bed

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