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To enhance the understanding of the behavior of active nematic, it is important to understand the behavior of topological defects. In this paper, we study the configuration of topological defects of a two-dimensional active nematic around a…

Soft Condensed Matter · Physics 2026-02-16 Hiroki Matsukiyo , Jun-ichi Fukuda

We formulate the statistical dynamics of topological defects in the active nematic phase, formed in two dimensions by a collection of self-driven particles on a substrate. An important consequence of the non-equilibrium drive is the…

Soft Condensed Matter · Physics 2018-09-12 Suraj Shankar , Sriram Ramaswamy , M. Cristina Marchetti , Mark J. Bowick

Non-equilibrium dynamics of topological defects can be used as a fundamental propulsion mechanism in microscopic active matter. Here, we demonstrate swimming of topological defect-propelled colloidal particles in (passive) nematic fluids…

Soft Condensed Matter · Physics 2021-09-30 Tianyi Yao , Žiga Kos , Yimin Luo , Edward B. Steager , Miha Ravnik , Kathleen J. Stebe

Active fluids display spontaneous turbulent-like flows known as active turbulence. Recent work revealed that these flows have universal features, independent of the material properties and of the presence of topological defects. However,…

Soft Condensed Matter · Physics 2026-03-19 Ido Lavi , Ricard Alert , Jean-François Joanny , Jaume Casademunt

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

Active processes drive and guide biological dynamics across scales -- from subcellular cytoskeletal remodelling, through tissue development in embryogenesis, to population-level bacterial colonies expansion. In each of these, biological…

Topological defects play a key role in two-dimensional active nematics, and a transient role in two-dimensional active polar fluids. In this paper, we study both the transient and long-time behavior of defects in two-dimensional active…

Soft Condensed Matter · Physics 2020-09-24 Farzan Vafa

Active materials are those in which individual, uncoordinated local stresses drive the material out of equilibrium on a global scale. Examples of such assemblies can be seen across scales from schools of fish to the cellular cytoskeleton…

Soft Condensed Matter · Physics 2022-09-30 Nitin Kumar , Rui Zhang , Steven A. Redford , Juan J. de Pablo , Margaret L. Gardel

In confluent cell monolayers, patterns of cell forces and motion are systematically altered near topological defects in cell shape. In turn, defects have been proposed to alter cell density, extrusion, and invasion, but it remains unclear…

Biological Physics · Physics 2025-08-11 Pradip K. Bera , Molly McCord , Jun Zhang , Jacob Notbohm

Inspired by recent experiments that highlight the role of nematic defects in the morphogenesis of epithelial tissues, we develop a minimal framework to study the dynamics of an active curved surface driven by its nematic texture. Allowing…

Soft Condensed Matter · Physics 2022-09-14 Farzan Vafa , L. Mahadevan

We develop an approximate, analytical model for the velocity of defects in active nematics by combining recent results for the velocity of topological defects in nematic liquid crystals with the flow field generated from individual defects…

Soft Condensed Matter · Physics 2024-11-27 Cody D. Schimming , C. J. O. Reichhardt , C. Reichhardt

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

Liquid shells (e.g. double emulsions, vesicles etc.) are susceptible to interfacial instability and rupturing when driven out of mechanical equilibrium. This poses a significant challenge for the design of liquid shell based micro-machines,…

Soft Condensed Matter · Physics 2019-10-30 Babak Vajdi Hokmabad , Kyle A. Baldwin , Carsten Krüger , Christian Bahr , Corinna C. Maass

Cultured stem cells have become a standard platform not only for regenerative medicine and developmental biology but also for biophysical studies. Yet, the characterization of cultured stem cells at the level of morphology and macroscopic…

Soft Condensed Matter · Physics 2022-06-23 Kyogo Kawaguchi , Ryoichiro Kageyama , Masaki Sano

Topological defects are increasingly being identified in various biological systems, where their characteristic flow fields and stress patterns are associated with continuous active stress generation by biological entities. Here, using…

Soft Condensed Matter · Physics 2022-11-09 Lasse Bonn , Aleksandra Ardaseva , Romain Mueller , Tyler N. Shendruk , Amin Doostmohammadi

We characterise the particlelike kinematics of charge-carrying topological defects in nematic media via a geometric field theory. This differs from the theory of electromagnetism, with which it is often compared, due to the absence of…

Soft Condensed Matter · Physics 2026-05-22 Joseph Pollard , Richard G. Morris

Topological defects play a central role in the physics of many materials, including magnets, superconductors and liquid crystals. In active fluids, defects become autonomous particles that spontaneously propel from internal active stresses…

Soft Condensed Matter · Physics 2024-06-12 Suraj Shankar , Luca V. D. Scharrer , Mark J. Bowick , M. Cristina Marchetti

We present a hydrodynamic model for a thin spherical shell of active nematic liquid crystal with an arbitrary configuration of defects. The active flows generated by defects in the director lead to the formation of stable vortices,…

Soft Condensed Matter · Physics 2017-11-13 Diana Khoromskaia , Gareth P. Alexander

In pulsating active matter, topological defects are motile despite the absence of any macroscopic flows and microscopic self-propulsion. We reveal that this motility arises from a ratchet effect: the mechanochemical coupling between local…

Soft Condensed Matter · Physics 2026-05-26 Luca Casagrande , Alessandro Manacorda , Etienne Fodor

Active nematics are fluids in which the components have nematic symmetry and are driven out of equilibrium due to the microscopic generation of an active stress. When the active stress is high, it drives flows in the nematic and can lead to…

Soft Condensed Matter · Physics 2025-11-10 Daniel J. G. Pearce , Berta Martínez-Prat , Jordi Ignés-Mullol , Francesc Sagués