Thermal expansion effects and heat conduction in granular materials
Watson L Vargas1, J J McCarthy
1Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 13, 2007
Summary
Thermal expansion in granular systems significantly increases particle forces and induces controllable compaction. Raising and lowering temperature, without mechanical input, enhances granular packing, aligning with experimental findings.
Area of Science:
- Physics
- Materials Science
- Computational Science
Background:
- Granular systems exhibit complex behaviors under thermal stress.
- Thermal expansion is known to influence particle interactions and system properties.
Purpose of the Study:
- To investigate the impact of thermal expansion on force distribution in 2D granular systems.
- To analyze the relationship between thermal heating, boundary conditions, and granular packing.
Main Methods:
- A simulation study was conducted on a 2D system of disks.
- Thermal heating was applied under two distinct boundary conditions (fixed walls).
- Steel particles were simulated with temperature increases of 50°C and 100°C.
Main Results:
- A significant increase in average force was observed for steel particles in fixed-wall systems.
- Thermal expansion induced particle compaction, leading to increased granular packing.
- Granular packing fraction evolution was accurately modeled by a fractional relaxation model (Mittag-Leffler law).
Conclusions:
- Thermal expansion is a controllable mechanism for enhancing granular packing without mechanical energy input.
- Simulation results are consistent with previous experimental observations of thermal expansion effects in granular materials.
- The Mittag-Leffler law effectively describes the packing fraction dynamics driven by thermal cycles.
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