Related Experiment Video
Updated: Apr 3, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
9.1K
Perspective on "Active Brownian particles moving in a random Lorentz gas"
C Reichhardt1, C J O Reichhardt2
1Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.
The European Physical Journal. E, Soft Matter
|April 2, 2026
Summary
Active matter particles in disordered media show similar subdiffusive behavior to Brownian particles near percolation. However, active particles reach steady states faster and exhibit lower effective diffusion at high activity due to self-trapping.
Area of Science:
- Physics
- Soft Matter Physics
- Statistical Mechanics
Background:
- Active matter systems, driven by internal energy, exhibit distinct dynamics compared to passive Brownian motion.
- Disordered media, such as porous materials or crowded environments, significantly influence particle transport.
Purpose of the Study:
- To compare the transport dynamics of active matter particles and Brownian particles in a random obstacle array.
- To investigate the effect of activity and obstacle density on particle diffusion and steady-state attainment.
Main Methods:
- Numerical simulations comparing active and Brownian particles in a 2D random obstacle array.
- Analysis of subdiffusive behavior and effective diffusion coefficients near the percolation threshold.
Main Results:
- Both active and Brownian particles exhibit identical subdiffusive behavior near the obstacle percolation density.
- Active particles attain a steady state more rapidly than Brownian particles.
- At high activity levels, active particles display reduced effective diffusion due to increased self-trapping.
Conclusions:
- Active matter dynamics in disordered media differ significantly from Brownian motion, particularly concerning steady-state attainment and effective diffusion.
- The findings highlight the importance of self-trapping effects in active matter within disordered environments.
- This research opens avenues for studying active particles in biological systems (e.g., bacteria in porous media) and engineered colloids.
Related Concept Videos
01:24The Kinetic Model of Gases
99
The kinetic model of gases explains the properties of a perfect gas using three main assumptions: molecules move in ceaseless random motion, their size is negligible compared to the distances between them, and they do not interact except during perfectly elastic collisions. The total energy of a gas is the sum of the kinetic energies of all its constituent molecules. The pressure exerted by the gas arises from the continual bombardment of the container walls by billions of colliding molecules.
99
01:10First Law: Particles in One-dimensional Equilibrium
8.5K
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...
8.5K
01:27Distribution of Molecular Speeds
6.0K
The motion of molecules in a gas is random in magnitude and direction for individual molecules, but a gas of many molecules has a predictable distribution of molecular speeds. This predictable distribution of molecular speeds is known as the Maxwell-Boltzmann distribution. The distribution of molecular speeds in liquids is comparable to that of gases but not identical and can help to understand the phenomenon of the boiling and vapor pressure of a liquid. Consider that a molecule requires a...
6.0K
01:12Kinetic Theory of an Ideal Gas
5.3K
A mole is defined as the amount of any substance that contains as many molecules as there are atoms in exactly 12 grams of carbon-12. An Italian scientist Amedeo Avogadro (1776–1856) formed the hypothesis that equal volumes of gas at equal pressure and temperature contain equal numbers of molecules, independent of the type of gas. Later, the hypothesis was developed to form the SI unit for measuring the amount of any substance.
The number of molecules in one mole is called...
The number of molecules in one mole is called...
5.3K
01:18First Law: Particles in Two-dimensional Equilibrium
17.0K
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...
17.0K
02:43Basic Postulates of Kinetic Molecular Theory: Particle Size, Energy, and Collision
39.1K
The ideal-gas equation, which is empirical, describes the behavior of gases by establishing relationships between their macroscopic properties. For example, Charles’ law states that volume and temperature are directly related. Gases, therefore, expand when heated at constant pressure. Although gas laws explain how the macroscopic properties change relative to one another, it does not explain the rationale behind it.
39.1K