Related Experiment Video
Updated: Sep 20, 2025
03:32
Author Spotlight: Collective Behavioral Analysis of the Nematode, Caenorhabditis elegans
Published on: August 25, 2023
1.1K
Small Obstacle in a Large Polar Flock
Joan Codina1,2, Benoît Mahault3, Hugues Chaté4,5,6
1Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325001, China.
Physical Review Letters
|June 10, 2022
Summary
A single obstacle can disrupt large polar flocks, causing flow reversals and chaotic dynamics. This new disordered phase emerges in simulations of self-propelled particles and Boltzmann equation truncations.
Area of Science:
- Physics
- Complex Systems
- Statistical Mechanics
Background:
- Polar flocks exhibit collective motion.
- Understanding emergent behaviors in large systems is crucial.
Purpose of the Study:
- Investigate the impact of obstacles on polar flock dynamics.
- Explore the emergence of new disordered phases.
Main Methods:
- Simulations of aligning self-propelled particles.
- Analysis of continuous-level phenomena using Boltzmann equation truncations.
Main Results:
- A small obstacle triggers counterpropagating bands and flow reversals.
- Interacting bands in large systems lead to chaotic dynamics and a new disordered phase.
Conclusions:
- Polar flocks are sensitive to local perturbations.
- The study reveals a novel disordered phase in active matter systems.
Related Concept Videos
01:29Potential Due to a Polarized Object
478
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
478
02:04Conservation of Small Populations
13.7K
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less...
13.7K
01:24Pole and System Stability
439
The transfer function is a fundamental concept representing the ratio of two polynomials. The numerator and denominator encapsulate the system's dynamics. The zeros and poles of this transfer function are critical in determining the system's behavior and stability.
Simple poles are unique roots of the denominator polynomial. Each simple pole corresponds to a distinct solution to the system's characteristic equation, typically resulting in exponential decay terms in the system's...
Simple poles are unique roots of the denominator polynomial. Each simple pole corresponds to a distinct solution to the system's characteristic equation, typically resulting in exponential decay terms in the system's...
439
01:01Group Polarization
35.7K
Group polarization is the strengthening of an original group attitude following the discussion of views within a group (Teger & Pruitt, 1967). That is, if a group initially favors a viewpoint, after discussion the group consensus is likely a stronger endorsement of the viewpoint. Conversely, if the group was initially opposed to a viewpoint, group discussion would likely lead to stronger opposition.
35.7K
01:18First Law: Particles in Two-dimensional Equilibrium
5.2K
Recall that a particle in equilibrium is one for which the external forces are balanced. Static equilibrium involves objects at rest, and dynamic equilibrium involves objects in motion without acceleration; but it is important to remember that these conditions are relative. For instance, an object may be at rest when viewed from one frame of reference, but that same object would appear to be in motion when viewed by someone moving at a constant velocity.
Newton's first law tells us about...
Newton's first law tells us about...
5.2K
01:10First Law: Particles in One-dimensional Equilibrium
7.1K
Newton's first law of motion states that a body at rest remains at rest, or if in motion, remains in motion at constant velocity, unless acted on by a net external force. It also states that there must be a cause for any change in velocity (a change in either magnitude or direction) to occur. This cause is a net external force. For example, consider what happens to an object sliding along a rough horizontal surface. The object quickly grinds to a halt, due to the net force of friction. If...
7.1K