A Study on Granular Media: Packing, Intruding, and Shocking

Open Access
Author:
Costantino, Daniel Jeffrey
Graduate Program:
Physics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
April 24, 2009
Committee Members:
  • Peter E Schiffer, Dissertation Advisor
  • Peter E Schiffer, Committee Chair
  • Moses Hung Wai Chan, Committee Member
  • Dezhe Jin, Committee Member
  • Chris J Marone, Committee Member
Keywords:
  • granular media
  • intruders
  • packing fraction
  • mechanical impacts
  • initiation motion
Abstract:
We studied four different aspects of granular media. The effect of filling parameters on packing fraction was investigated. We found that in sufficiently large containers compared to the grains, packing fraction is reasonably constant as long as the grains to do not enter free fall during the filling process. We also examined the force needed to initiate the upward motion of an intruder buried under grains. This force is linearly dependent on the size of the particles making up the pile and also increases with the diameter of the intruder itself. By submerging grains in different liquids, we altered the effective acceleration due to gravity and explored the effect of this on the force needed to drag a cylinder through the grains. This force was linearly dependent on the acceleration due to gravity; we propose a geometric explanation for its magnitude. A container of grains with a hole in its center was subjected to impacts. We considered the resulting flux of grains and looked for changes in behavior depending on the bottom surface of the container.