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Title: A numerical investigation of the contact dynamics and bulk behaviour of adhesive particles
Author: Wilson, Robert
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2017
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Adhesive interactions between individual particles in a granular system often lead to complex and unintuitive phenomena on the macro-scale. In this thesis the behaviour of adhesive particles in various situations is investigated numerically, using the Discrete Element Method. The first system of interest is the fluidized bed. The effects of varying the elastic modulus, coefficient of restitution, and coefficient of friction of adhesive particles on fluidized bed dynamics are investigated. By considering the effects that these parameters have on the statistics of macroscopic system properties, and the motion of bubbles in the system, a number of complex relationships have been uncovered. The influence of surface roughness and contact adhesion on the rolling of dry particles is also studied. Rough particle surfaces are approximated using an array of spheres, the properties of which are informed by random processes. This approach has allowed the derivation of an analytical model, which accurately describes the resistance to initial rolling of a static particle, and the slowing of a rolling particle. Finally, the properties of piles of adhesive particles are investigated. The angle of repose is found to increase with increasing adhesive forces, but also to decrease with increasing pile size for adhesive particles. A study of the pressure distribution at the base of the pile has revealed that adhesion and friction both contribute to a measurable drop in pressure under the centre. Results suggest that the manifestation of this phenomenon may relate to the packing density of the particles in the pile.
Supervisor: Dini, Daniele ; van Wachem, Berend ; Haynes, Peter Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral