Gas-mediated impact dynamics in fine-grained granular materials.
John R Royer1, Eric I Corwin, Peter J Eng
1James Franck Institute and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA.
Physical Review Letters
|August 7, 2007
Summary
The presence of interstitial gas significantly alters how noncohesive granular media respond to impact. Removing gas changes behavior from fluid-like to highly compressible and dissipative.
Area of Science:
- Physics of granular materials
- Fluid dynamics
- Material science
Background:
- Noncohesive granular media display unique behaviors under impact, distinct from solids and liquids.
- The role of interstitial gas in mediating these responses is not fully understood.
Purpose of the Study:
- To investigate the influence of interstitial gas on the dynamic response of granular media.
- To characterize the transition in material behavior with varying gas presence.
Main Methods:
- High-speed X-ray radiography was employed to track the motion of a steel sphere.
- Experiments were conducted in a bed of fine, loose granular material with controlled gas evacuation.
Main Results:
- A transition in behavior was observed with changes in gas pressure.
- At atmospheric pressure, the granular medium exhibited near-incompressible, fluid-like motion.
- With gas evacuation, the medium showed highly compressible and dissipative characteristics.
Conclusions:
- Interstitial gas plays a critical role in the impact response of granular media.
- The findings provide insights into drag forces within granular systems.
- Understanding these gas-mediated effects is crucial for modeling granular material dynamics.
