Research Projects

Active matter systems are ubiquitously found in nature from microscopic to macroscopic length scales, exhibiting various emergent complex non-equilibrium phenomena such as flocking of birds, swarms, fish schools, etc. These systems deal with particles that are capable of consuming energy and converting it into directed motions. The constant energy flow makes the system out of equilibrium, where the usual descriptions of equilibrium statistical mechanics are not warranted. Also, the detailed understanding of these phenomena is still lacking due to the complexity of the system, making the field an active field of research. In earlier studies, model systems consisting of active Brownian particles have been considered to investigate non-equilibrium phenomena such as collective dynamics, giant number fluctuations, and motility-induced phase separation. Further intriguing non-equilibrium effects have also been observed for the model systems consisting of self-propelled polymers or filaments made of active particles. The studies on active filaments are very crucial to understand the structural organization of bacterial systems and the dynamics of cells due to the active motion of microtubules or actin bio-polymers in the presence of motor proteins. Therefore, the system consisting of active filaments has gained significant attention. Previous studies on the collective dynamics of active Brownian particles have shown that confinement can lead to phase behaviors distinct from those observed in unconfined systems. It is expected that the spatial confinement can alter the collective properties of active filaments. Nevertheless, confinement occurs in biological systems due to the finite size of the cells and can play a significant role in the function of biological systems. In this context, we aim to study the effects of confinement on the collective motion and structural organization of active filaments in two dimensions. Each filament is to be modeled as a chain of active Brownian particles (i.e., monomers). Molecular dynamics simulations are to be performed in the LAMMPS software by solving the Langevin equation for each active monomer of each filament. In simulations, steric interactions among the monomers are considered to avoid the overlapping among the filaments, and active forces act along the local tangents of the filaments, giving rise to the directed motion. We aim to explore collective dynamics and structural organization of the system by varying various model parameters such as number density, rigidity, and activity of the filaments. Cyanobacteria are known to reverse their self-propelled direction randomly in time. Therefore, we also aim to investigate the effect of velocity reversal on the phase behavior of confined systems. Our study is expected to provide valuable insights into the collective behavior of active filaments, contributing to a better understanding of dynamic processes in biological systems.