3D avalanching of rod-like granular materials

Aspect ratio versus angle of repose

By Walter Hopkins

Ken Desmond

Jess Gallagher

Scott Barker

Background

• Aspect ratio

• Angle of repose

• Maximum angle

Motivation

• Application with mixing polymers

• Oil Industry

• Transition between solid body behavior and granular behavior?

Set up of Experiment

• There are four rollers guiding the cell

• Camera mounted to take video through cell center

• Cell rotates slowly

• Belt driven on the non transparent side of the cell

• Acrylic cell and rods

• Quasi static

Rods

We will be looking at the behavior of the following prolate granular materials:

• Acrylic rods with aspect ratios from 8 to 40

• Rice grains

The acrylic rods will have diameters ranging between 1/16” and ¼”

The cell

• Different diameter cells will be used

• No variable cell material

• Variable end cap.

• Non transparent end of cell driven by motor

Acquiring Data

• One camera mounted at the center of the rotating drum

• Might try to do particle tracking by coloring and additional camera

• The video data is used to determine the different states of avalanche

Analyzing Data

• Averaging the images will give us the angle of repose

• Subtracting the images shows us which particles are moving

• Programs are written in IDL

Goals

• Maximum angle dependent on aspect ratio

• Do the dimensions of the cell have any relevance

• Are there any other interesting effects that occur in rod avalanching that doesn’t occur with other granular materials