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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…

We numerically investigate the morphology and disclination line dynamics of active nematic droplets in three dimensions. Although our model only incorporates the simplest possible form of achiral active stress, active nematic droplets…

Soft Condensed Matter · Physics 2021-04-07 Liam J. Ruske , Julia M. Yeomans

From incompressible flows to electrostatics, harmonic functions can provide solutions to many two-dimensional problems and, similarly, the director field of a planar nematic can be determined using complex analysis. We derive a closed-form…

Soft Condensed Matter · Physics 2024-12-03 Simon Čopar , Žiga Kos

The spontaneous creation of disclinations is a defining characteristic of active nematics, which is rarely observed in equilibrium systems or other active matter systems. Thus, understanding the mechanics of disclinations is crucial for…

Soft Condensed Matter · Physics 2025-07-01 Yingyou Ma , Christopher Amey , Aparna Baskaran , Michael F. Hagan

Nematic liquid crystals can dramatically reconfigure under dynamic forcing, providing exciting opportunities in active matter. Here, we study a hybrid disk colloid rotated by an external field which generates a dynamic companion topological…

Soft Condensed Matter · Physics 2026-05-26 Qi Xing Zhang , Claire Dore , Mojtaba Rajabi , Edward B. Steager , Kathleen J. Stebe

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

We investigate similarities in the micro-structural dynamics between externally driven and actively driven nematics. Walls, lines of strong deformations in the director field, and topological defects are characteristic features of an active…

Soft Condensed Matter · Physics 2015-04-28 Sumesh P. Thampi , Ramin Golestanian , Julia M. Yeomans

Topological defects are one of the most conspicuous features of liquid crystals. In two dimensional nematics, they have been shown to behave effectively as particles with both, charge and orientation, which dictate their interactions. Here,…

Soft Condensed Matter · Physics 2021-07-14 Daniel J. G. Pearce , Karsten Kruse

While studies of active nematics in two dimensions have shed light on various aspects of the flow regimes and topology of active matter, three-dimensional properties of topological defects and chaotic flows remain unexplored. By confining a…

Soft Condensed Matter · Physics 2018-07-18 Tyler N. Shendruk , Kristian Thijssen , Julia M. Yeomans , Amin Doostmohammadi

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

We describe a numerical investigation of a continuum model of an active nematic, concentrating on the regime of active turbulence. Results are presented for the effect of three parameters, activity, elastic constant and rotational diffusion…

Soft Condensed Matter · Physics 2015-06-18 Sumesh P. Thampi , Ramin Golestanian , Julia M. Yeomans

The study of liquid crystals at equilibrium has led to fundamental insights into the nature of ordered materials, as well as to practical applications such as display technologies. Active nematics are a fundamentally different class of…

Soft Condensed Matter · Physics 2015-08-19 Stephen J. DeCamp , Gabriel S. Redner , Aparna Baskaran , Michael F. Hagan , Zvonimir Dogic

We study the active flow around isolated defects and the self-propulsion velocity of $+1/2$ defects in an active nematic film with both viscous dissipation (with viscosity $\eta$) and frictional damping $\Gamma$ with a substrate. The…

Soft Condensed Matter · Physics 2022-01-28 Jonas Rønning , M. Cristina Marchetti , Mark J. Bowick , Luiza Angheluta

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

We investigate the effects of extrinsic curvature on the turbulent behavior of a 2D active nematic confined to the surface of a cylinder. The surface of a cylinder has no intrinsic curvatrue and only extrinsic curvature. A nematic field…

Soft Condensed Matter · Physics 2020-08-26 D. J. G. Pearce

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

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

We study emergent dynamics in a viscous drop subject to interfacial nematic activity. Using hydrodynamic simulations, we show how the interplay of nematodynamics, activity-driven flows and surface deformations gives rise to a sequence of…

Soft Condensed Matter · Physics 2024-04-19 Mohammadhossein Firouznia , David Saintillan

Point-like topological defects are singular configurations that occur in a variety of in and out of equilibrium systems with two-dimensional orientational order. As they are associated with a nonzero circuitation condition, the presence of…

Statistical Mechanics · Physics 2023-07-13 Jacopo Romano , Benoît Mahault , Ramin Golestanian

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