arXiv subjects

K. R. Prathyusha

Publications and source records attributed to K. R. Prathyusha.

7 recordsLinked to original sources

arXiv2025

Active polymers translocate faster in confinement

Living organisms employ diverse strategies to navigate confined environments. Inspired by translocation observations on California blackworms (\textit{Lumbriculus variegatus}), we combine biological experiments and active-polymer simulations to examine how confinement and stiffness govern translocation. Active filaments translocate fastest when the channel width is comparable to their diameter, with escape time determined by propulsion speed, filament length, and channel geometry. In wider channels, activity and flexibility induce reorientation-dominated conformational changes that prolong escape. A single dimensionless ratio linking confinement to stiffness captures the transition from axis-aligned escape with short wall deflections for stiffer filaments, to reorientation-controlled motion with blob-like shapes for flexible filaments. These results provide a unified physical framework for active translocation in confinement and suggest design principles for flexible robotic filaments in complex environments.

cond-mat.soft↗

arXiv2025

Collecting Particles in Confined Spaces by Active Filamentous Matter

Biological and robotic systems often operate in confined environments where material must be gathered without centralized control. Inspired by the effective collection strategies of aquatic worms (Lumbriculus variegatus and Tubifex tubifex), we investigate how active filaments autonomously aggregate dispersed particles. We study this process across four platforms: living worms, a robotic chain, Brownian dynamics simulations of active polymers, and a coarse-grained toy model. We show that aggregation emerges from repeated contact and body deformation, and demonstrate that clustering dynamics are governed by filament length and bending stiffness. Across systems, particle gathering follows a shared aggregation-fragmentation process, with the steady-state average cluster size scaling as $\langle s\rangle_L\sim W/D^2$, where W is the effective width of the path cleared by the filament and D the domain size. We find that filament flexibility modulates W, enabling more flexible filaments to sweep larger areas and collect more particles. These results establish a unifying framework for understanding how shape and flexibility influence transport and organization in active filament systems and filamentous robots.

cond-mat.soft↗

arXiv2024

Anomalous fluctuations in a droplet of chemically active colloids or enzymes

Chemically active colloids or enzymes cluster into dense droplets driven by their phoretic response to collectively generated chemical gradients. Employing Brownian dynamics simulation techniques, our study of the dynamics of such a chemically active droplet uncovers a rich variety of structures and dynamical properties, including the full range of fluid-like to solid-like behaviour, and non-Gaussian positional fluctuations. Our work sheds light on the complex dynamics of the active constituents of metabolic clusters, which are the main drivers of non-equilibrium activity in living systems.

cond-mat.soft↗

arXiv2023

Worm Blobs as Entangled Living Polymers: From Topological Active Matter to Flexible Soft Robot Collectives

Recently, long and slender living worms have garnered significant interest because of their impressive ability to exhibit diverse emergent behaviors in highly entangled physical and topological conditions. These worms can form an active viscoelastic, three-dimensional soft entity known as the 'blob', which can behave like a solid, flow like a liquid, and even respond to external stimuli such as light to locomote or change shape. To understand the behavior of the blob, it is crucial to consider the high degree of conformational entanglement that individual units can achieve because of their high aspect ratio and tunable activity. This topologically active collective necessitates reevaluating established soft matter concepts in polymer physics to advance the development of active polymer-like materials. Our understanding of the complex emergent dynamics of the worm blob promises to catalyze further research into the behavior of entangled active polymers and guide the design of synthetic topological active matter and bioinspired tangling soft robot collectives.

cond-mat.soft↗

arXiv2022

A computational study of a transversely propelling polymer and passive particles

Using Langevin dynamics simulations, we study a system of transversely propelling filament and passive Brownian particles. We consider a polymer whose monomers experience a constant propulsion force perpendicular to the local tangent in the presence of passive particles undergoing thermal fluctuations in two dimensions. We demonstrate that the sideways propelling polymer can act as a sweeper to collect the passive Brownian particles, mimicking a shuttle-cargo system. The number of particles the polymer collects during its motion increases with time and finally saturates to a maximum number. Moreover, the velocity of the polymer decreases as the particles get trapped due to the extra drag they generate. Rather than going to zero, the velocity eventually reaches a terminal value close to the contribution from the thermal velocity when it collects the maximum load. We show that, apart from the length of the polymer, the propulsion strength and the number of passive particles are deciding factors for the maximum trapped particles. In addition, we demonstrate that the collected particles arrange themselves in a triangular, closed, packed state, similar to what has been observed in

cond-mat.soft↗

arXiv2022

Emergent conformational properties of end-tailored transversely propelling polymers

We study the dynamics and conformations of a single active semiflexible polymer whose monomers experience a propulsion force perpendicular to the local tangent, with the end beads being different from the inner beads ("end-tailored"). Using Langevin simulations, we demonstrate that, apart from sideways motion, the relative propulsion strength between the end beads and the polymer backbone significantly changes the conformational properties of the polymers as a function of bending stiffness, end-tailoring and propulsion force. Expectedly, for slower ends the polymer curves away from the moving direction, while faster ends lead to opposite curving, in both cases slightly reducing the center of mass velocity compared to a straight fiber. Interestingly, for faster end beads there is a rich and dynamic morphology diagram: the polymer ends may get folded together to 2D loops or hairpin-like conformations that rotate due to their asymmetry in shape and periodic flapping motion around a rather straight state during full propulsion is also possible. We rationalize the simulations using scaling and kinematic arguments and present the state diagram of the conformations. Sideways propelled fibers comprise a rather unexplored and versatile class of self-propellers, and their study will open novel ways for designing, e.g. motile actuators or mixers in soft robotics.

cond-mat.soft↗

arXiv2017

Dynamically Generated Patterns in Dense Suspensions of Active Filaments

We use Langevin dynamics simulations to study dynamical behaviour of a dense planar layer of active semi-flexible filaments. Using the strength of active force and the thermal persistence length as parameters, we map a detailed phase diagram and identify several non-equilibrium phases in this system. In addition to a slowly flowing melt phase, we observe that for sufficiently high activity, collective flow accompanied by signatures of local polar and nematic order appears in the system. This state is also characterised by strong density fluctuations. Furthermore, we identify an activity-driven cross-over from this state of coherently flowing bundles of filaments to a phase with no global flow, formed by individual filaments coiled into rotating spirals. This suggests a mechanism where the system responds to activity by changing the shape of active agents, an effect with no analogue in systems of active particles without internal degrees of freedom.

cond-mat.soft↗