scholarly journals Experimental and numerical study of granular flow and fence interaction

2004 ◽  
Vol 38 ◽  
pp. 135-138 ◽  
Author(s):  
Thierry Faug ◽  
Mohamed Naaim ◽  
Florence Naaim-Bouvet
Keyword(s):  
Granular Flow ◽  
Numerical Study ◽  
Slope Angle ◽  
Granular Flows ◽  
Snow Avalanches ◽  
Shallow Water Theory ◽  
Gravity Driven ◽  
Deposition Processes ◽  
Set Up ◽  
Good Agreement

AbstractDense snow avalanches are regarded as dry granular flows. This paper presents experimental and numerical modelling of deposition processes occurring when a gravity-driven granular flow meets a fence. A specific experimental device was set up, and a numerical model based on shallow-water theory and including a deposition model was used. Both tools were used to quantify how the retained volume upstream of the fence is influenced by the channel inclination and the obstacle height. We identified two regimes depending on the slope angle. In the slope-angle range where a steady flow is possible, the retained volume has two contributions: deposition along the channel due to the roughness of the bed and deposition due to the fence. The retained volume results only from the fence effects for higher slopes. The effects of slope on the retained volume also showed these two regimes. For low slopes, the retained volume decreases strongly with increasing slope. For higher slopes, the retained volume decreases weakly with increasing slope. Comparison between the experiments and computed data showed good agreement concerning the effect of fence height on the retained volume.

Numerical Simulation and Experimental Study of Particle Dynamics in a Rotating Drum with Flights

2017 ◽  
Vol 899 ◽  
pp. 65-70 ◽  
Author(s):  
Suellen Mendonça Nascimento ◽  
F.P. de Lima ◽  
Claudio Roberto Duarte ◽  
Marcos Antonio de Souza Barrozo
Keyword(s):  
Experimental Data ◽  
Granular Flow ◽  
Numerical Study ◽  
Operating Conditions ◽  
Particle Dynamic ◽  
Multiphase Model ◽  
Theoretical Studies ◽  
Rotating Drum ◽  
Dynamics Of Particles ◽  
Good Agreement

Rotary dryers are widely used in various industries. Although numerous research efforts have focused on characterizing the dynamics of these equipments, the design of rotating dryers is complex, and theoretical studies are necessary to gain an in-depth understanding of the dynamics of particles in these dryers. This paper aims to investigate the particle dynamic behavior in a rotating drum with flights, based on CFD and experimental results. In the numerical study it was used the Eulerian-Eulerian multiphase model along with the kinetic theory of granular flow. The holdups of solids in the flights were compared with experimental data, using a methodology created specifically for this purpose. The simulated results were in good agreement with the experimental data and the present work has shown that the Eulerian approach has been able to predict the fluid dynamics behavior in different operating conditions.

scholarly journals Force fluctuations at the transition from quasi-static to inertial granular flow

Soft Matter ◽  
2019 ◽  
Vol 15 (42) ◽  
pp. 8532-8542 ◽  
Author(s):  
A. L. Thomas ◽  
Zhu Tang ◽  
Karen E. Daniels ◽  
N. M. Vriend
Keyword(s):  
Granular Flow ◽  
Granular Flows ◽  
Force Fluctuations ◽  
Gravity Driven

We analyse the rheology of gravity-driven, dry granular flows in experiments where individual forces within the flow bulk are measured.

scholarly journals A simple analytical model for pressure on obstacles induced by snow avalanches

2010 ◽  
Vol 51 (54) ◽  
pp. 1-8 ◽  
Author(s):  
Thierry Faug ◽  
Benoit Chanut ◽  
Rémi Beguin ◽  
Mohamed Naaim ◽  
Emmanuel Thibert ◽  
...  
Keyword(s):  
Analytical Model ◽  
Dead Zone ◽  
Granular Flows ◽  
Mitigation Measures ◽  
Snow Avalanches ◽  
Simple Analytical Model ◽  
Inclined Plane ◽  
Gravity Driven ◽  
D Model ◽  
Protection Dams

AbstractThe forces snow avalanches are able to exert on protection dams or buildings are of crucial interest in order to improve avalanche mitigation measures and to quantify the mechanical vulnerability of structures likely to be damaged by snow avalanches. This paper presents an analytical model that is able to calculate these forces taking into account dead-zone mechanisms. First, we present a 2-D analytical hydrodynamic model describing the forces on a wall overflown by gravity-driven flows down an inclined plane. Second, the 2-D model is successfully validated on discrete simulations of granular flows. Third, we provide ingredients to extend the 2-D model to flows of dry and cold snow. Fourth, we propose a simplified 3-D analytical model taking into account lateral fluxes. Finally, the predictions from the simplified 3-D analytical model are successfully compared to recent measurements on two full-scale snow avalanches released at the Lautaret site in France.

scholarly journals Pullout simulation of post installed chemically bonded anchors in UHPFRC

2018 ◽  
Vol 199 ◽  
pp. 11007
Author(s):  
Fabien Delhomme ◽  
Michael Brun
Keyword(s):  
Numerical Model ◽  
High Performance ◽  
Failure Modes ◽  
Numerical Study ◽  
Design Stage ◽  
Embedment Depth ◽  
Concrete Damage ◽  
Pullout Failure ◽  
Set Up ◽  
Good Agreement

An experimental and numerical study was completed in order to examine the mechanical behaviour of post-installed bonded anchors in ultra-high performance fibre reinforced concrete with a compressive strength higher than 130 MPa. The aim was to analyse the failure mechanisms in static pullout tests and to suggest a simple numerical model, which can be employed in a design stage, to reproduce the global behaviour of the anchor. The experimental observations show that a combined pullout and concrete cone failure occurred for an embedment depth of 40 mm and a steel rod failure for an embedment depth of 100 mm. The numerical model was set up using Abaqus software, by adopting the concrete damage plastic model and a surface-based cohesive behaviour for the interface concrete-anchor. The obtained failure modes and ultimate loads are in good agreement with experimental results. A minimum embedment depth of 50 mm was assessed to prevent a pullout failure of the anchor.

A Lattice-Based Cellular Automata Modeling Approach for Granular Flow Lubrication

2005 ◽  
Vol 128 (2) ◽  
pp. 358-364 ◽  
Author(s):  
Venkata K. Jasti ◽  
C. Fred Higgs
Keyword(s):  
Cellular Automata ◽  
Granular Flow ◽  
Solid Lubricant ◽  
Granular Flows ◽  
Complex Flows ◽  
The Past ◽  
Modeling Approach ◽  
Ca Model ◽  
Model Benchmark ◽  
Good Agreement

Liquid lubricants break down at extreme temperatures and promote stiction in micro-/nanoscale environments. Consequently, using flows of solid granular particles as a “dry” lubrication mechanism in sliding contacts was proposed because of their ability to carry loads and accommodate surface velocities. Granular flows are highly complex flows that in many ways act similar to fluids, yet are difficult to predict because they are not well understood. Granular flows are composed of discrete particles that display liquid and solid lubricant behavior with time. This work describes the usefulness of employing lattice-based cellular automata (CA), a deterministic rule-based mathematics approach, as a tool for modeling granular flows in tribological contacts. In the past work, granular flows have been modeled using the granular kinetic lubrication (GKL) continuum modeling approach. While the CA modeling approach is constructed entirely from rules, results are in good agreement with results from the GKL model benchmark results. Velocity results of the CA model capture the well-known slip behavior of granular flows near boundaries. Solid fraction results capture the well-known granular flow characteristic of a highly concentrated center region. CA results for slip versus roughness also agree with GKL theory.

Granular Flow Lubrication: A Lattice-Based Cellular Automata Modeling Approach

2005 ◽  
Author(s):  
V. K. Jasti ◽  
C. F. Higgs
Keyword(s):  
Cellular Automata ◽  
Granular Flow ◽  
Solid Lubricant ◽  
Granular Flows ◽  
Complex Flows ◽  
Shear Cell ◽  
Modeling Approach ◽  
Ca Model ◽  
Model Benchmark ◽  
Good Agreement

Liquid lubricants break down at extreme temperatures and promote stiction in micro/nano-scale environments. Consequently, using flows of solid granular particles as a “dry” lubrication mechanism in sliding contacts was proposed, because of their ability to carry loads and accommodate surface velocities. Granular flows are highly complex flows that in many ways act similar to fluids, yet are difficult to predict because they are not well understood. Granular flows are composed of discrete particles which display fluid and solid lubricant behavior with time. This work describes the usefulness of employing lattice-based cellular automata (CA) as a tool for modeling granular flows in tribological contacts. The granular kinetic lubrication (GKL) continuum modeling approach has been successful at predicting trends gleaned from experiments conducted with granules in a couette shear cell. These results are used as a benchmark for determining the effectiveness of the CA modeling results. While the CA model was constructed entirely from rule-based mathematics, velocity and solid fraction results from the simulations were in good agreement with those from the GKL model benchmark results.

Numerical study of gravity-driven dense granular flows on flow behavior characterization

2016 ◽  
Vol 297 ◽  
pp. 144-152 ◽  
Author(s):  
Yu Li ◽  
Nan Gui ◽  
Xingtuan Yang ◽  
Jiyuan Tu ◽  
Shengyao Jiang
Keyword(s):  
Numerical Study ◽  
Flow Behavior ◽  
Granular Flows ◽  
Gravity Driven ◽  
Dense Granular Flows

scholarly journals Laboratory Measurements of Light Scattering by Dust Particles

1996 ◽  
Vol 150 ◽  
pp. 409-413
Author(s):  
Patrick P. Combet ◽  
Philippe L. Lamy
Keyword(s):  
Light Scattering ◽  
Laser Beam ◽  
Mie Theory ◽  
Spherical Particles ◽  
Dust Particles ◽  
Laboratory Measurements ◽  
Scattering Function ◽  
Hene Laser ◽  
Set Up ◽  
Good Agreement

AbstractWe have set up an experimental device to optically study the scattering properties of dust particles. Measurements over the 8 — 174° interval of scattering angles are performed on a continuously flowing dust loaded jet illuminated by a polarized red HeNe laser beam. The scattering is averaged over the population of the dust particles in the jet, which can be determined independently, and give the “volume scattering function” for the two directions of polarization directly. While results for spherical particles are in good agreement with Mie theory, those for arbitrary particles show conspicuous deviations.

scholarly journals A numerical study of gravity-driven instability in strongly coupled dusty plasma. Part 1. Rayleigh–Taylor instability and buoyancy-driven instability

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Vikram S. Dharodi ◽  
Amita Das
Keyword(s):  
Dusty Plasma ◽  
Numerical Study ◽  
Fluid Model ◽  
Density Region ◽  
Strongly Coupled ◽  
Rising Bubble ◽  
Inhomogeneous Density ◽  
Gravity Driven ◽  
The Individual ◽  
Strongly Coupled Dusty Plasma

Rayleigh–Taylor (RT) and buoyancy-driven (BD) instabilities are driven by gravity in a fluid system with inhomogeneous density. The paper investigates these instabilities for a strongly coupled dusty plasma medium. This medium has been represented here in the framework of the generalized hydrodynamics (GHD) fluid model which treats it as a viscoelastic medium. The incompressible limit of the GHD model is considered here. The RT instability is explored both for gradual and sharp density gradients stratified against gravity. The BD instability is discussed by studying the evolution of a rising bubble (a localized low-density region) and a falling droplet (a localized high-density region) in the presence of gravity. Since both the rising bubble and falling droplet have symmetry in spatial distribution, we observe that a falling droplet process is equivalent to a rising bubble. We also find that both the gravity-driven instabilities get suppressed with increasing coupling strength of the medium. These observations have been illustrated analytically as well as by carrying out two-dimensional nonlinear simulations. Part 2 of this paper is planned to extend the present study of the individual evolution of a bubble and a droplet to their combined evolution in order to understand the interaction between them.

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