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Related papers: Defect Dynamics in Active Polar Fluids vs. Active …

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Polar active matter - including animal herds, aggregates of motile cells and active colloids - often forms coordinated migration patterns, such as flocking. This orderly motion can be disrupted by full-integer topological defects…

Soft Condensed Matter · Physics 2026-05-26 Luiza Angheluta , Anna Lång , Emma Lång , Stig Ove Bøe

We report on the emergence of stable self-propelled bound defects in monolayers of active nematics, which form virtual full-integer topological defects in the form of vortices and asters. Through numerical simulations and analytical…

Soft Condensed Matter · Physics 2020-10-26 Kristian Thijssen , Amin Doostmohammadi

Topological defects in active polar fluids exhibit complex dynamics driven by internally generated stresses, reflecting the deep interplay between topology, flow, and non-equilibrium hydrodynamics. Feedback control offers a powerful means…

Soft Condensed Matter · Physics 2025-07-28 Abhinav Singh , Petros Koumoutsakos

Living materials at different length scales manifest active nematic features such as orientational order, nematic topological defects, and active nematic turbulence. Using numerical simulations we investigate the impact of fluid inertia on…

Soft Condensed Matter · Physics 2022-08-10 Roozbeh Saghatchi , Mehmet Yildiz , Amin Doostmohammadi

Active nematics, in their pure form, have demonstrated a plethora of dynamic and steady state behaviors, including large-scale dynamic structures, collective flows, and intricate multi-spatial temporal dynamics. This complexity further…

Statistical Mechanics · Physics 2024-07-09 Partha Sarathi Mondal , Pawan Kumar Mishra , Tamás Vicsek , Shradha Mishra

The growing interest in active nematics and the emerging evidence of the relevance of topological defects in biology asks for reliable data analysis tools to identify, classify and track such defects in simulation and microscopy data. We…

Soft Condensed Matter · Physics 2020-02-10 Dennis Wenzel , Michael Nestler , Sebastian Reuther , Maximilian Simon , Axel Voigt

The presence and significance of active topological defects is increasingly realised in diverse biological and biomimetic systems. We introduce a continuum model of polar active matter, based on conservation laws and symmetry arguments,…

Soft Condensed Matter · Physics 2021-06-08 Aboutaleb Amiri , Romain Mueller , Amin Doostmohammadi

We study the spatiotemporal patterns that emerge when an active nematic film is topologically constraint. These topological constraints allow to control the non-equilibrium dynamics of the active system. We consider ellipsoidal shapes for…

Soft Condensed Matter · Physics 2017-03-13 Francesco Alaimo , Christian Köhler , Axel Voigt

Active nematics contain topological defects which under sufficient activity move, create and annihilate in a chaotic quasi-steady state, called active turbulence. However, understanding active defects under confinement is an open challenge,…

Soft Condensed Matter · Physics 2019-10-02 Simon Čopar , Jure Aplinc , Žiga Kos , Slobodan Žumer , Miha Ravnik

We numerically study the coarsening of topological defects in 2D polar active matter and make several interesting observations and predictions. (i) The long time state is characterized by nonzero density of defects, in stark contrast to…

Soft Condensed Matter · Physics 2025-09-30 Soumyadeep Mondal , Pankaj Popli , Sumantra Sarkar

Active matter is naturally out of equilibrium which results in the emergence of diverse dynamic steady states, including the omnipresent chaotic state known as the active turbulence. However, much less is known how active systems…

Soft Condensed Matter · Physics 2023-04-07 Nika Kralj , Miha Ravnik , Žiga Kos

We use numerical simulations to investigate the hydrodynamic behavior of the interface between nematic (N) and isotropic (I) phases of a confined active liquid crystal. At low activities, a stable interface with constant shape and velocity…

Soft Condensed Matter · Physics 2021-02-25 Rodrigo C. V. Coelho , Nuno A. M. Araújo , Margarida M. Telo da Gama

Topological defects are singularities in material fields that play a vital role across a range of systems: from cosmic microwave background polarization to superconductors, and biological materials. Although topological defects and their…

Soft Condensed Matter · Physics 2017-10-06 Luca Giomi , Žiga Kos , Miha Ravnik , Anupam Sengupta

Topological defects are fundamental to the collective dynamics of non-equilibrium systems and in active matter, mediating spontaneous flows, dynamic self-organization, and emergent pattern formation. Here, we reveal critical states in…

Liquid crystals inevitably possess topological defect excitations generated through boundary conditions, applied fields or in quenches to the ordered phase. In equilibrium pairs of defects coarsen and annihilate as the uniform ground state…

Soft Condensed Matter · Physics 2013-06-05 Luca Giomi , Mark J. Bowick , Xu Ma , M. Cristina Marchetti

We numerically model a two-dimensional active nematic confined by a periodic array of fixed obstacles. Even in the passive nematic, the appearance of topological defects is unavoidable due to planar anchoring by the obstacle surfaces. We…

Soft Condensed Matter · Physics 2024-01-25 Cody D. Schimming , C. J. O. Reichhardt , C. Reichhardt

Using novel micro-printing techniques, we develop a versatile experimental setup that allows us to study how lateral confinement tames the active flows and defect properties of the microtubule/kinesin active nematic system. We demonstrate…

Active nematics are an important new paradigm in soft condensed matter systems. They consist of rod-like components with an internal driving force pushing them out of equilibrium. The resulting fluid motion exhibits chaotic advection, in…

The persistent dynamics in systems out of equilibrium, particularly those characterized by annihilation and creation of topological defects, is known to involve complicated spatiotemporal processes and is deemed difficult to control. Here…

Soft Condensed Matter · Physics 2022-11-22 Zhi-Feng Huang , Hartmut Löwen , Axel Voigt

Using agent-based simulations of self-propelled particles subject to short-range repulsion and nematic alignment we explore the dynamical phases of a dense active material confined to the surface of a sphere. We map the dynamical phase…

Soft Condensed Matter · Physics 2018-04-25 Silke Henkes , M. Cristina Marchetti , Rastko Sknepnek