Flow and clogging of soft particles in 2D hoppers Öffentlichkeit

Abstract

I study the outflow of soft particles through quasi-two-dimensional hoppers with both experiments and simulations. The experiments utilize spheres made with soft hydrogel, silicone rubber and glass. The hopper chamber has an adjustable exit width and tilt angle (the latter to control the magnitude of gravitational forcing). My simulation mimics the experiments using purely two-dimensional soft particles with viscous interactions but no friction. Results from both simulations and experiments demonstrate that clogging is easier for reduced gravitational force or stiffer particles. For particles with low or no friction, the average number of particles in a clogging arch depends only on the ratio between hopper exit width and particle’s diameter. In contrast for the silicone rubber particles with larger frictional interactions, arches are larger than the low friction case. Additionally, an analysis of the number of particles left in the hopper when clogging occurs provides evidence for a hydrostatic pressure effect that is relevant for the clogging of soft particles, but not so for the harder (glass) or frictional (silicone rubber) particles. Through simulations, I also studied the flux of soft particles flowing through two-dimensional hoppers. I derived a flux law to describe the flux under different gravitational conditions and varying exit width. The flux law agrees with simulation data except when the exit width is too large.

Table of Contents

Introduction............................................................ 1

Experimental Methods............................................ 2

Simulation Methods................................................ 6

Results.................................................................... 8

Conclusion............................................................ 25

Bibliography.......................................................... 27

About this Honors Thesis

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School	Emory College
Department	Physics
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Physics, Condensed Matter Physics, General
Stichwort	Granular particles Soft matter Clogging
Committee Chair / Thesis Advisor	Eric R. Weeks, Emory University
Committee Members	Suresh Venapally, Emory University Effrosyni Seitaridou, Emory University

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