Dynamics of sedimenting active Brownian particles

Area of Science:

• Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Active Brownian particles (ABPs) exhibit self-propelled motion, leading to complex collective behaviors.
• Understanding the dynamics of individual ABPs is crucial for predicting emergent phenomena in active matter systems.
• Gravity and passive fluctuations significantly influence particle trajectories and system-level properties.

Purpose of the Study:

• To develop an analytical model for the stochastic dynamics of a single sedimenting active Brownian particle in 3D.
• To investigate the time evolution of particle density and polarization.
• To compare theoretical predictions with Brownian dynamics simulations and experimental data.

Main Methods:

• Analytical solution of the Fokker-Planck equation for a 3D active Brownian particle.
• Brownian dynamics simulations to study collective motion and particle activity effects.
• Comparison of theoretical results with experimental data from Palacci et al. (2010).

Main Results:

• The analytical solution accurately describes the dynamics of a single active Brownian particle.
• The model captures the time evolution of density and polarization, including steady-state solutions.
• Simulations and experiments show good qualitative agreement with the developed theoretical framework.

Conclusions:

• The study provides a robust theoretical framework for understanding the behavior of sedimenting active Brownian particles.
• The findings highlight the importance of activity and external forces in governing active matter dynamics.
• The excellent agreement with experimental data validates the proposed model for active particle systems.