Simulation of flow and mixing of particles in a rotating and rocking cylinder

Abstract

Granular material in a cylindrical vessel undergoing rotational and rocking motions is modeled using a discrete element method. Rotational motion supplemented by rocking is compared to purely rotational motion via linear density profiles, velocity fields, and axial concentration profiles. The rocking motion, which imparts a time-dependent flow perturbation to purely rotational motion, dramatically enhanced mixing in laborat o y studies. Simulation results appear to agree well with experimental results and observations. IntroductionMany technical fields deal with mixing of granular materials, including chemical, agricultural, ceramic, mechanical, civil and soil engineering, the life sciences, physics, and pharmacy. Although researchers in these fields consider a wide range of physical characteristics and flow regimes, they share a common interest: the need to understand and characterize bulkflow powder behavior. Powder processing has been recently characterized by chemical engineers as having a legacy of neglect (Ennis et al., 1994). Awareness of this neglect has motivated a recent resurgence of both experimental investigations (McCarthy et al., 1996;Hill and Kakalios, 1995;Brone et al., 1997) and theoretical approaches (Johnson et al., 1990;Edwards and Mounfield, 1996). It has become fashionable in a sense to study powders, not only because of their complexity but also because there is a growing need in industry to reliably manufacture high-quality products.Although practitioners have attempted to handle powder problems using empirical approaches, more detailed studies of the physics of powders are required. Some researchers have suggested that granular materials might be a different state of matter (Jaeger et al., 1996). Interest in the physics of powders has increased dramatically in the past decade, starting with the analysis of sand piles (Baxter et al., 1989(Baxter et al., , 1993Bak and Chen, 1991), prompted by analogies with self-organized critical systems (Bak et al., 1988). Fundamental questions concerning how and why granular materials behave alternaCorrespondence concerning this article should be addressed to F. J. Muzrio tively like a liquid when flowing down an inclined chute and like a solid when forming a sloping surface remain to be answered (Glanz, 1995). A growing research community is currently investigating microscopic theories (Jaeger et al., 1996;Jaeger and Nagel, 1992;Evesque and Stefani, 1991;Evesque et al., 1992; Mehta, 19941, as well as unit operations typically found in industry, such as blending, sampling, discharge, fluidization, and granulation. The kinetic theory developed for fast-flowing low-density solids has achieved some success in modeling Couette flows and flows down inclined planes, but industrial systems are often more complex. Civil and soil engineers are mainly interested in strain effects (failure) produced by external forces and the effect of time on the development of strain. The chemical engineering community, on the other hand, has focused primarily on mixing and tran...

Niobium carbide synthesis by solid-gas reaction using a rotating cylinder reactor

“…5) The recirculation pattern inside the cylinders without the occurrence of stagnation points was observed for a filling fraction ( ) of (Wightman et al, 1998) …”

Material and Interaction Properties of Selected Grains and Oilseeds for Modeling Discrete Particles

“…Different modeling techniques such as continuum models and discrete element models (Wightman et al, 1998) have potential to simulate grain commingling in elevator equipment. The discrete element method (DEM) is considered one of the most promising techniques to simulate movement of individual particles (Wightman et al, 1998) such as grain kernals in bucket elevator equipment.…”

“…The discrete element method (DEM) is considered one of the most promising techniques to simulate movement of individual particles (Wightman et al, 1998) such as grain kernals in bucket elevator equipment. DEM is an explicit numerical scheme in which particle interaction is monitored contact by contact and the motion of individual particles is modeled (LoCurto et al, 1997b).…”

“…Limited data on grain commingling during handling in grain elevators (Ingles et al, 2003(Ingles et al, , 2006 make it difficult to accurately predict levels of impurities that would propagate through grain handling systems. Thus, a validated mechanistic model for predicting grain commingling in various types of elevator equipment will be valuable for extending the knowledge of grain commingling beyond current experimental studies.Different modeling techniques such as continuum models and discrete element models (Wightman et al, 1998) have potential to simulate grain commingling in elevator equipment. The discrete element method (DEM) is considered one of the most promising techniques to simulate movement of individual particles (Wightman et al, 1998) such as grain kernals in bucket elevator equipment.…”

Optimization of Operating Conditions in a High-Shear Mixer Using DEM Model: Determination of Optimal Fill Level.

“…Such reported examples included particle behavior in fluidized bed, 10,11) as well as kinetic motion of particles and mixing processes 12) in a coating drum, 13,14) Vbender 15) and double corn bender. 15,16) However, there seem to be no reports available about the simulation of kinetic motion and mixing processes, with attention given to a highshear mixer frequently used in preparation of pharmaceuticals or about the research on optimization of operating conditions on the basis of discrete element method.…”