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