Lynn Daniels
PhD, University of Pennsylvania, 2010



Top-down view of plastic rods. The rods are 1/2" in length and have aspect ratio 5.3, occupying an area fraction of 65%. At such high area fractions, interplay between volume exclusion interactions and the inclination of each rod to propel itself along its long axis results in dramatic compression waves. (For comparable systems of bidisperse spheres, waves are not observed.) The slowly-fillng voids remaining after the wave front has passed through give rise to anomalously large number fluctuations.

1 ball
2 ball