Spatiotemporal chaotic unjamming and jamming in granular avalanches
1Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China.
Scientific Reports
|January 31, 2015
Summary
Researchers measured particle dynamics in a rotating drum, revealing entangled spatiotemporal chaotic dynamics during avalanches. These findings validate theoretical models and offer insights into jamming and unjamming transitions.
Area of Science:
- Physics
- Complex Systems
- Statistical Mechanics
Background:
- Granular materials exhibit complex behaviors like jamming and unjamming.
- Avalanches in granular systems are driven by spatiotemporal chaotic dynamics.
- Understanding particle motion during transitions is crucial for modeling granular flow.
Purpose of the Study:
- To investigate the spatiotemporal chaotic dynamics of particle unjamming and jamming in a rotating drum experiment.
- To directly measure the first Lyapunov vector and particle velocity for insights into spatial correlations.
- To validate theoretical models of granular flow dynamics.
Main Methods:
- Utilized a rotating drum partially filled with bidisperse disks to simulate avalanches.
- Directly measured the magnitudes of the first Lyapunov vector (δu(t)) and particle velocity (v(t)).
- Analyzed the spatial correlation (Cδu,v) between the Lyapunov vector and velocity.
Main Results:
- Spatial correlation (Cδu,v) was found to be slightly larger near unjamming than jamming.
- Particle velocity (v(t)) exhibited exponential growth for unstable particles and decay with fluctuations after a maximum.
- Direct measurements validated theoretical models by Banigan et al. (2013).
Conclusions:
- Spatiotemporal chaotic dynamics of avalanche particles are entangled, leading to temporal correlations in macroscopic system properties.
- The study provides the first experimental validation of theoretical models for granular avalanche dynamics.
- A simple model is proposed to explain the observed particle dynamics and correlations.
Related Concept Videos
01:15Elastic Collisions: Case Study
21.3K
Elastic collision of a system demands conservation of both momentum and kinetic energy. To solve problems involving one-dimensional elastic collisions between two objects, the equations for conservation of momentum and conservation of internal kinetic energy can be used. For the two objects, the sum of momentum before the collision equals the total momentum after the collision. An elastic collision conserves internal kinetic energy, and so the sum of kinetic energies before the collision equals...
21.3K
01:00Elastic Collisions: Introduction
15.8K
An elastic collision is one that conserves both internal kinetic energy and momentum. Internal kinetic energy is the sum of the kinetic energies of the objects in a system. Truly elastic collisions can only be achieved with subatomic particles, such as electrons striking nuclei. Macroscopic collisions can be very nearly, but not quite, elastic, as some kinetic energy is always converted into other forms of energy such as heat transfer due to friction and sound. An example of a nearly...
15.8K
01:16Precipitate Formation and Particle Size Control
7.2K
In precipitation gravimetry, the precipitating agent should react specifically or selectively with the analyte. While a specific reagent reacts with the analyte alone, a selective reagent can react with a limited number of chemical species.
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...
The obtained precipitate should be either a pure substance of known composition or easily converted to one by a simple process, such as ignition or drying. In addition, the precipitate should be insoluble and easily filterable. In general, filterability...
7.2K
01:06Forced Oscillations
8.3K
When an oscillator is forced with a periodic driving force, the motion may seem chaotic. The motions of such oscillators are known as transients. After the transients die out, the oscillator reaches a steady state, where the motion is periodic, and the displacement is determined.
8.3K
01:23Propagation of Action Potentials
16.0K
The propagation of an action potential refers to the process by which a nerve impulse, or "action potential," travels along a neuron.
Neurons (nerve cells) have a resting membrane potential, with a slightly negative charge inside compared to outside. This is maintained by ion channels, such as sodium (Na+) and potassium (K+) channels, which control the flow of ions. When a stimulus, like a touch or a signal from another neuron, triggers the neuron, sodium channels open, allowing sodium ions to...
Neurons (nerve cells) have a resting membrane potential, with a slightly negative charge inside compared to outside. This is maintained by ion channels, such as sodium (Na+) and potassium (K+) channels, which control the flow of ions. When a stimulus, like a touch or a signal from another neuron, triggers the neuron, sodium channels open, allowing sodium ions to...
16.0K
00:59Propagation of Uncertainty from Random Error
2.2K
An experiment often consists of more than a single step. In this case, measurements at each step give rise to uncertainty. Because the measurements occur in successive steps, the uncertainty in one step necessarily contributes to that in the subsequent step. As we perform statistical analysis on these types of experiments, we must learn to account for the propagation of uncertainty from one step to the next. The propagation of uncertainty depends on the type of arithmetic operation performed on...
2.2K