May 22-27, 2016
Many fluidization processes like granulation, agglomeration, encapsulation or coating exhibit conditions where liquid bridges form between particles (1), resulting in strong particle-particle interactions at the microscopic scale. DEM and DEM-CFD simulations are able to show how the particle-scale phenomena determine the overall behavior of a wet particulate material in industrial systems.
Description of the capillary interaction between spherical particles in the pendular regime (i.e. with liquid bridges forming on a one-to-one basis) has been long studied and characterized, particularly in the case of spheres of the same size. When polydisperse systems are considered, the formation, interaction force and rupture of a liquid bridge follow paths that can differ significantly from the monodisperse case. For example, the validity of the toroidal or parabolic approximation of the bridge shape (2) is much more limited. Additionally, upon rupture the relative amount of liquid remaining with the bigger or smaller particles has not been addressed in general.
In the present work, the rigorous solutions of the Young-Laplace equations for the determination of the liquid bridge shape, its interaction force and rupture characteristics are found by means of an effective continuation technique. Use of the code allows critical (e.g. rupture) conditions to be found relatively easily as a function of the prescribed size ratio, liquid volume, contact angle, inter-particle distance. Also, it is shown that the volume repartition upon rupture can be estimated by assuming the bridge to break at the neck. Exemplary results for various ranges of the parameters will be shown and discussed.
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- D. Megias-Alguacil, L.J. Gauckler. Accuracy of the toroidal approximation for the calculus of concave and convex liquid bridges between particles. Granular Matter, 13: 487-492, 2011.
Alberto Di Renzo, Andrea Lorenti, and Francesco P. Di Maio, "Microscopic modelling of capillary liquid bridge force and volume repartition for DEM simulations of polydisperse systems" 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/156