Quantitative comparison of hydrodynamic and elastoplastic approaches for modeling granular flow in silo

Abstract

Hydrodynamic and elastoplastic theories are two commonly used continuum approaches for modeling granular materials. Here, the elastoplastic approach is extended to incorporate the rheology of dense granular flow, which therefore allows a quantitative comparison with the hydrodynamic approach under the same setting of rheological laws, material parameters, and numerical method. The flow patterns yielded by two approaches are apparently similar and the discharge rates are close. Yet the elastoplastic approach creates a narrow dome‐like flow zone in contrast to the wide cone‐like flow zone generated by the hydrodynamic approach. The shear localization is also less prominent in elastoplastic modeling owing to the existence of elastic deformation. The stresses predicted by two approaches match well in flow zones but show significant differences in stagnant zones. The proposed elastoplastic approach incorporating flow rheology can be used generally in both solid and fluid states of granular materials. © 2019 American Institute of Chemical Engineers AIChE J, 65: e16533, 2019

Analysis of granular rheology in a quasi-two-dimensional slow flow by means of discrete element method based simulations

“…Granular rheology, which has the objective of developing constitutive models for flow of particles, has been the subject of in-depth study for more than six decades , with the pioneering work of R. A. Bagnold 22 being an important initial milestone. Today, it is reasonably well-understood to the point that it is being employed for continuum simulations of many different kinds of granular flows [48][49][50][51] . Kinetic theory applied to grains has provided the theoretical foundation for development of granular rheology 23,24 .…”

DEM simulation of dense granular flows in a vane shear cell: Kinematics and rheological laws

“…Dense granular flows are widely found in industrial processing equipment such as silos [1,2], pneumatic conveyors [3], vibrating inclined planes [4] and rotating drums [5]. Difficulties are reported in the simulation of granular flows in such devices due to the lack of a universal rheological model [2,6].…”

“…Dense granular flows are widely found in industrial processing equipment such as silos [1,2], pneumatic conveyors [3], vibrating inclined planes [4] and rotating drums [5]. Difficulties are reported in the simulation of granular flows in such devices due to the lack of a universal rheological model [2,6]. Rheological behaviors of dry granular flows are often described in three flow regimes, which are distinguished as quasi-static (I 0.001), intermediate (0.001 I 1.0) and collisional (I 1.0) regimes based on an inertial number parameter I =γd p / P/ρ p withγ being the shear rate, d p particle diameter, ρ p particle intrinsic density, and P the confining pressure [7,8,9].…”

“…MiDi [7] suggested a µ(I) relation, which has successfully described the rheological behaviors of dense granular flows [7,8,18]. Its modified versions have been applied to modeling of dense granular flows in several flow configurations [1,2,3,19,20,21]. The formulation developed by Jop et al [19] is written as…”

A Review of Computational Models for the Flow of Milled Biomass Part II: Continuum-Mechanics Models

“…For conventional granular materials (i.e., dense and incompressible grains), efforts were made by superimposing hypoplastic and viscousrheology models, 21,87,89,136 and by the introduction of rheology into the frictional term of the Drucker−Prager model. 137,138 For milled biomass materials, bridging multiregime flow behavior with single a comprehensive constitutive model and an appropriate numerical framework is so far an unexplored area that deserves dedicated study. The challenge of calibration for constitutive parameters comes from the variability of biomass feedstocks.…”