RHEOLOGY OF DENSE GRANULAR FLOW

2001 ◽  
Vol 04 (04) ◽  
pp. 419-428
Author(s):  
THOMAS C. HALSEY ◽  
DENIZ ERTAŞ ◽  
GARY S. GREST ◽  
LEONARDO E. SILBERT ◽  
DOV LEVINE
Keyword(s):  
Granular Flow ◽  
Three Dimensions ◽  
Scaling Relations ◽  
Constant Density ◽  
Numerical Studies ◽  
Flow Geometry ◽  
Stress Directions ◽  
Coulomb Type ◽  
Dense Granular Flow ◽  
Dense Granular Flows

We have performed numerical studies of dense granular flows on an incline with a rough bottom in two and three dimensions. This flow geometry produces a constant density profile that satisfies scaling relations of the Bagnold, rather than the viscous, kind. No surface-only flows were observed. The bulk and the surface layer differ in their rheology, as evidenced by the change in principal stress directions near the surface; a Mohr–Coulomb type failure criterion is seen only near the surface. In the bulk, normal stress anomalies are observed both in two and in three dimensions. We do not observe isostaticity in static frictional piles obtained by arresting the flow.

Magnetic-Based Particle Tracking in a Dense Granular Shear Flow

2019 ◽  
Author(s):  
Xingtian Tao ◽  
Huixuan Wu
Keyword(s):  
Particle Tracking ◽  
Granular Flow ◽  
Magnetic Particle ◽  
Individual Particle ◽  
Shear Stresses ◽  
Dense Granular Flow ◽  
Couette Cell ◽  
Granular Shear ◽  
Individual Particles ◽  
Dense Granular Flows

Abstract Granular material is ubiquitous in nature and plays a significant role in industry. Researchers have paid a lot of attention to density and velocity distributions of dense granular flows. However, the motion of individual particle is hard to capture because visualizing individual particles in a dense granular flow, especially in 3D, is very difficult and could be expansive. Here we use the magnetic particle tracking (MPT) technique to capture the motion of a single particle in a sheared dense granular flow. The accuracy of MPT is quantified using experimental results. The sheared granular flow is generated in a Couette cell by rotating a plate at the bottom of a cylinder container. It is able to generate different shear stresses by controlling the speed of the plate. By tracking the magnetic particle in the cylinder, we can capture the velocity of an individual particle at different locations in the granular flow.

A Convex Complementarity Approach for Simulating Large Granular Flows

2010 ◽  
Vol 5 (3) ◽  
Author(s):  
Alessandro Tasora ◽  
Mihai Anitescu
Keyword(s):  
Granular Flow ◽  
Complementarity Problems ◽  
Particle Interaction ◽  
Granular Flows ◽  
Rigid Bodies ◽  
Integration Time ◽  
Frictional Contacts ◽  
Physical Experiments ◽  
Dense Granular Flow ◽  
Number Of Particles

Aiming at the simulation of dense granular flows, we propose and test a numerical method based on successive convex complementarity problems. This approach originates from a multibody description of the granular flow: all the particles are simulated as rigid bodies with arbitrary shapes and frictional contacts. Unlike the discrete element method (DEM), the proposed approach does not require small integration time steps typical of stiff particle interaction; this fact, together with the development of optimized algorithms that can run also on parallel computing architectures, allows an efficient application of the proposed methodology to granular flows with a large number of particles. We present an application to the analysis of the refueling flow in pebble-bed nuclear reactors. Extensive validation of our method against both DEM and physical experiments results indicates that essential collective characteristics of dense granular flow are accurately predicted.

Experimental and computational studies of dense granular flow: Transition from quasi-static to intermediate regime in a Couette shear device

2012 ◽  
Vol 220 ◽  
pp. 7-14 ◽  
Author(s):  
V. Vidyapati ◽  
M. Kheiripour Langroudi ◽  
J. Sun ◽  
S. Sundaresan ◽  
G.I. Tardos ◽  
...  
Keyword(s):  
Granular Flow ◽  
Computational Studies ◽  
Flow Transition ◽  
Intermediate Regime ◽  
Dense Granular Flow

Regularization by compressibility of the μ(I) model of dense granular flow

2018 ◽  
Vol 30 (7) ◽  
pp. 073302 ◽  
Author(s):  
J. D. Goddard ◽  
J. Lee
Keyword(s):  
Granular Flow ◽  
Dense Granular Flow

Vibratory Finishing of Immobilized Cylinders

2012 ◽  
Vol 565 ◽  
pp. 278-283 ◽  
Author(s):  
Stephen Wan ◽  
Takashi Sato ◽  
Andry Hartawan
Keyword(s):  
Surface Roughness ◽  
Flow Field ◽  
Granular Flow ◽  
Flow Direction ◽  
General Purpose ◽  
Vibratory Finishing ◽  
Cfd Simulations ◽  
Dense Granular Flow ◽  
The Media ◽  
Computational Fluid Dynamics Cfd

We report preliminary results from an on-going study investigating the effect of fixing workpieces within the media flow field contained in a typical vibratory finishing bowl. To this end, we studied the surface roughness evolution over the surfaces of workpieces with generic geometries such as cylinders. A granular flow dynamics model applicable to dense granular flow and a previously derived process equation were invoked in order to respectively describe the flow of the abrasive media; and the roughness distribution in terms of the granular pressure and velocity. By solving the granular flow field for the pressure and velocity distribution on a given geometry using a general purpose computational fluid dynamics (CFD) code, we were able to analyse changes in surface roughness distribution from the process equation. The immobilized cylinders were submerged in the top portion of the media flow field so as to facilitate comparison between media flow past the workpieces as experimentally observed and as predicted by the CFD simulations. We conclude with an analysis, based on both experimental and predicted results, of the way in which media flow direction biases the surface roughness distribution on an immobilized cylinder.

scholarly journals Numerical Simulations for Large Deformation of Geomaterials Using Molecular Dynamics

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Ziyang Zhao ◽  
Jun Zhang
Keyword(s):  
Molecular Dynamics ◽  
Large Deformation ◽  
Granular Flow ◽  
Three Dimensional ◽  
Damping Force ◽  
Viscous Material ◽  
Runout Distance ◽  
Models Comparison ◽  
Dense Granular Flow ◽  
High Degree

From the microperspective, this paper presents a model based on a new type of noncontinuous theoretical mechanical method, molecular dynamics (MD), to simulate the typical soil granular flow. The Hertzian friction formula and viscous damping force are introduced in the MD governing equations to model the granular flow. To show the validity of the proposed approach, a benchmark problem of 2D viscous material flow is simulated. The calculated final flow runout distance of the viscous material agrees well with the result of constrained interpolated profile (CIP) method as reported in the literature. Numerical modeling of the propagation of the collapse of three-dimensional axisymmetric sand columns is performed by the application of MD models. Comparison of the MD computational runout distance and the obtained distance by experiment shows a high degree of similarity. This indicates that the proposed MD model can accurately represent the evolution of the granular flow. The model developed may thus find applications in various problems involving dense granular flow and large deformations, such as landslides and debris flow. It provides a means for predicting fluidization characteristics of soil large deformation flow disasters and for identification and design of appropriate protective measures.

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