Flow Patterns and Wall Stresses in a Mass-Flow Bunker

Blair-Fish, P. M.; Bransby, P. L.

doi:10.1115/1.3438096

Cited by 51 publications

(20 citation statements)

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“…As reported above, studies on two-dimensional hoppers 13,14 show that the flow of granular material in a twodimensional hopper occurs in an unsteady manner, first flowing down one side of the hopper then down the other. In addition, these and other studies [11][12][13][14] show the presence of asymmetric rupture surfaces, within which the solid fraction of the material falls below its average value ͑although no quantitative density measurements were made͒. These rupture surfaces are apparently formed as a by-product of the asymmetric unsteadiness in the flow.…”

Section: Results Of the Simulation Unsteady Hopper Flowsmentioning

confidence: 66%

“…This unsteadiness was attributed to periodic stress fluctuations measured by Blair-Fish and Bransby. 13 ͑Langston and Tüzün 17 observed a similar unsteadiness in their funnel-flow computer simulations.͒ The unsteady flow was associated with the lower density rupture zones [11][12][13][14] although they gave no quantitative measurement of the magnitude of the velocity fluctuations. By itself, the unsteadiness seems to contradict the general assumption that the material is simultaneously yielding at every internal point and the density changes seem to contradict the general assumption of incompressibility and critical state behavior.…”

Section: Introductionmentioning

confidence: 87%

“…Very little can be done also to determine appropriate boundary conditions to be applied near the exit; this is a very practical concern since these conditions determine the hopper discharge rate. 7 Some of the most interesting experiments [11][12][13][14][15][16] examined the interior flow in two-dimensional hoppers by the use of x rays. The earliest of these studies, by Athey et al, 11 noticed distinct low density rupture zones that roughly followed stress characteristics and remained in the hopper at the termination of flow.…”

Section: Introductionmentioning

confidence: 99%

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Computer simulation of hopper flow

Potapov

Campbell

1996

Physics of Fluids

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This paper describes two-dimensional computer simulations of granular flow in plane hoppers. The simulations can reproduce an experimentally observed asymmetric unsteadiness for monodispersed particle sizes, but also could eliminate it by adding a small amount of polydispersity. This appears to be a result of the strong packings that may be formed by monodispersed particles and is thus a noncontinuum effect. The internal stress state was also sampled, which among other things, allows an evaluation of common assumptions made in granular material models. These showed that the internal friction coefficient is far from a constant, which is in contradiction to common models based on plasticity theory which assume that the material is always at the point of imminent yield. Furthermore, it is demonstrated that rapid granular flow theory, another common modeling technique, is inapplicable to this problem even near the exit where the flow is moving its fastest.

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Section: Results Of the Simulation Unsteady Hopper Flowsmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Computer simulation of hopper flow

Potapov

Campbell

1996

Physics of Fluids

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“…Concerning the general flow behaviour during discharge of silos, numerous experimental studies have been carried out [6,[12][13][14][15][16]. General characterisation of the funnel flow, which may be subdivided into the semi-mass flow and the internal funnel flow, has been established for the flat-bottomed silos.…”

Section: Introductionmentioning

confidence: 99%

A numerical study of wall pressure and granular flow in a flat-bottomed silo

Yin

Ooi

2015

Powder Technology

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JY 2015, 'A numerical study of wall pressure and granular flow in a flat-bottomed silo ', Powder Technology, vol. 282,. https://doi. AbstractThis paper presents a numerical study of the granular flow in the discharge of a flat-bottomed model silo.The behaviour of the stored granular material is modelled using the finite element (FE) method based on an Arbitrary Lagrangian-Eulerian (ALE) frame of reference, which has shown advantageous performance over the classical FE methods in simulating the silo filling and discharge process in a series of studies leading up to this investigation. Experimental results have been used to validate the computational model using the ALE technique. The spatial distribution and time history of the pressures acting on the vertical silo walls predicted by the FE model are found to resemble well the test results. A semi-mass flow pattern has been predicted by the numerical model, which is very consistent with the corresponding experimental observation. With the validated numerical model, the flow behaviour specifically under a flat-bottomed geometry of silos is examined. Based on the velocity distribution in the granular material, a critical velocity ratio criterion is proposed and used to identify the flow channel boundary. A further numerical study has shown that the flow behaviour in the flat-bottomed silo is closely related to the shear strength of the material, which is represented by the internal friction angle for the cohesionless sand considered in the present study.

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“…Optical techniques are commonly used in the analysis of velocity profiles near the transparent silo walls. The X-ray technique was frequently applied to obtain information from deeper flow layers [36,37]. Also, other non-invasive measurement techniques were applied to register granular flow, density and velocity fields in flowing zones, among others spy-holes, radio transmitters, positron emission [38], magnetic resonance imaging, radioactive tracers, and ultrasonic speckle velocimetry.…”

Section: Methodsmentioning

confidence: 99%