arXiv subjects

Sattwik Sadhu

Publications and source records attributed to Sattwik Sadhu.

2 recordsLinked to original sources

arXiv2026

Dynamics and stability of inertial flexible chains under follower activity

The dynamics of flexible polymers and chains under follower activity is known to produce diverse nonequilibrium states. A prominent feature of such systems is the emergence of periodic motion arising from the coupling between internal activity and chain conformation. Recently, it has been shown that flexible and extensible chains of active particles exhibit rich dynamical patterns in the overdamped limit, where inertia is negligible. Here, we study the complex dynamics of a flexible and extensible chain of active particles under follower activity when inertia is significant. Using numerical simulations, we quantify the chain dynamics as a function of chain length ($N$), segment mass, and activity. To rationalize the numerical results, we develop theoretical descriptions in the limit of short chains ($N=3$) and long chains ($N \gg 1$). In both these limits, we derive approximate expressions for the bond lengths and bond angles along the contour, which show excellent agreement with the numerical results. In addition, for short chains, we derive the stability conditions for a periodic motion as a function of segment mass and activity. For long chains ($N\gg1$) we identify parameter regime in which the circular, periodic solution becomes structurally unstable. Our theoretical and numerical analysis provides insights into the emergence of ordered and periodic behaviour in active chains.

cond-mat.soft↗

arXiv2025

Active chain spirograph: Dynamic patterns formed in extensible chains due to follower activity

Follower activity results in a large variety of conformational and dynamical states in active chains and filaments. These states are formed due to the coupling between chain geometry and the local activity. We study the origin and emergence of such patterns in noiseless, flexible active chains. In the overdamped limit, we observed a range of dynamical steady states for different chain lengths ($N$). The steady-state planar trajectories of the centre-of-mass of the chain include circles, periodic waves, and quasiperiodic, bound trajectories resembling spirographic patterns. In addition, out-of-plane initial configuration also leads to the formation of 3D structures, including globular and supercoiled helical structures. For the shortest chain with three segments $(N=3)$, the chain always moves in a circular trajectory. Such circular trajectories are also observed in the limit of large chain lengths $(N \gg 1)$. We analytically study the dynamical patterns in these two limiting cases, which show quantitative and qualitative matches with numerical simulations. Our analytical study also provides an estimate of the limiting $N$ where the large chain length behaviour is expected. These analyses reveal the existence of such intricately periodic patterns in active chains, arising due to the follower activity.

cond-mat.soft↗