Fluidization of irregular particles - Part I: A discrete element method to model collisions between non-convex particles
May 22-27, 2016
The flow dynamics of a fluidized bed can be very complicated. As the solid volume fraction is generally high, particle-particle collisions cannot be ignored. Many studies in the literature deal with perfectly spherical particles while very few deal with non-spherical ones and even less with angular or non-convex particles. However, these irregularly shaped particles are not uncommon in chemical engineering. Among others, Escudié et al (1) showed that the particle shape influences markedly the dynamics of such a system. We suggest an accurate and efficient way to model collisions between particles of (almost) arbitrary shape, that can be integrated into a comprehensive modeling of a fluidized bed. For that purpose, we develop a Discrete Element Method (DEM) combined with a soft particle contact model that treats the contact between bodies of various shape and size (2). In particular, for non-convex bodies, our strategy is based on decomposing a non-convex body into a set of convex ones (3). Therefore, our novel method can be called “glued convex method”, as an extension of the popular “glued-spheres” method (4). It hence uses all the features involved in DEM simulations of convex bodies, such as the contact detection strategy based on a Gilbert-Johnson-Keerthi algorithm (5) and the linked-cell spatial sorting which accelerates the contact resolution (6). The problem of multiple contact requires a particular attention (4,7). The method is implemented in our granular dynamics code Grains3D. As an illustration of the powerful modelling capabilities of Grains3D, we show results of simulation of settling non-convex catalytic pellets in a cylindrical chemical reactor.
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Andriarimina Daniel Rakotonirina, Anthony Wachs, Jean-Yves Delenne, and Farhang Radjai, "Fluidization of irregular particles - Part I: A discrete element method to model collisions between non-convex particles" in "Fluidization XV", Jamal Chaouki, Ecole Polytechnique de Montreal, Canada Franco Berruti, Wewstern University, Canada Xiaotao Bi, UBC, Canada Ray Cocco, PSRI Inc. USA Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/fluidization_xv/182
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