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We derive a fully covariant theory of the hydrodynamics of nematic and polar active surfaces, subjected to internal and external forces and torques. We study the symmetries of polar and nematic surfaces and find that in addition to 5…

Soft Condensed Matter · Physics 2023-01-12 Guillaume Salbreux , Frank Jülicher , Jacques Prost , Andrew Callan-Jones

The morphology of a mixture made of a polar active gel immersed in an isotropic passive fluid is studied numerically. Lattice Boltzmann method is adopted to solve the Navier-Stokes equation and coupled to a finite-difference scheme used to…

Soft Condensed Matter · Physics 2019-11-22 Livio Nicola Carenza , Giuseppe Gonnella , Antonio Lamura , Giuseppe Negro

We consider the derivation and numerical solution of the flow of passive and active polar liquid crystals, whose molecular orientation is subjected to a tangential anchoring on an evolving curved surface. The underlying passive model is a…

Computational Physics · Physics 2019-01-18 Ingo Nitschke , Sebastian Reuther , Axel Voigt

We overview the properties of nonlinear guided waves and (bright and dark) spatial optical solitons in a periodic medium created by a sequence of linear and nonlinear layers. First, we consider a single layer with a cubic nonlinear response…

Pattern Formation and Solitons · Physics 2009-04-01 Andrey A. Sukhorukov , Yuri S. Kivshar

Active fluids are intrinsically out-of-equilibrium systems due to the internal energy injection of the active constituents. We show here that a transition from a motion-less isotropic state towards a flowing polar one can be possibly driven…

Soft Condensed Matter · Physics 2021-05-12 M. G. Giordano , F. Bonelli , L. N. Carenza , G. Gonnella , G. Negro

We introduce a closure model for coarse-grained kinetic theories of polar active fluids. Based on a quasi-equilibrium approximation of the particle distribution function, the model closely captures important analytical properties of the…

Soft Condensed Matter · Physics 2022-06-17 Scott Weady , David B. Stein , Michael J. Shelley

Living materials such as biological tissues or bacterial colonies are collections of heterogeneous entities of different sizes, capable of autonomous motion, and often capable of cooperating. Such a degree of complexity brings to collective…

Soft Condensed Matter · Physics 2024-01-24 Matteo Paoluzzi , Demian Levis , Ignacio Pagonabarraga

We study a reaction-diffusion equation with an integral term describing nonlocal consumption of resources. We show that a homogeneous equilibrium can lose its stability resulting in appearance of stationary spatial structures. It is a new…

Analysis of PDEs · Mathematics 2007-05-23 Stephane Genieys , Vitaly Volpert , Pierre Auger

A new class of pattern forming systems is identified and investigated: anisotropic systems that are spatially inhomogeneous along the direction perpendicular to the preferred one. By studying the generic amplitude equation of this new class…

Pattern Formation and Solitons · Physics 2015-10-28 B. Kaoui , A. Guckenberger , A. Krekhov , F. Ziebert , W. Zimmermann

Meso-scale turbulence was originally observed experimentally in various suspensions of swimming bacteria, as well as in the collective motion of active colloids. The corresponding large-scale dynamical patterns were reproduced in a simple…

Soft Condensed Matter · Physics 2021-03-30 Vasco M. Worlitzer , Gil Ariel , Avraham Be'er , Holger Stark , Markus Bär , Sebastian Heidenreich

We develop the hydrodynamic theory of dry, polar ordered, active matter (``flocking") with autochemotaxis; i.e., self-propelled entities moving in the same direction, each emitting a substance which attracts the others (e.g., ants). We find…

Soft Condensed Matter · Physics 2024-01-22 Maxx Miller , John Toner

We derive the Hydrodynamics for a system of N active, spherical, underdamped particles, interacting through conservative forces. At the microscopic level, we represent the evolution of the particles in terms of the Kramers equation for the…

Statistical Mechanics · Physics 2022-03-15 Umberto Marini Bettolo Marconi , Andrea Puglisi , Lorenzo Caprini

Hydrodynamic equations for an isotropic solution of active polar filaments are derived from a microscopic mean-field model of the forces exchanged between motors and filaments. We find that a spatial dependence of the motor stepping rate…

Soft Condensed Matter · Physics 2015-06-24 T. B. Liverpool , M. Cristina Marchetti

We develop and study the hydrodynamic theory of flocking with autochemotaxis. This describes large collections of self-propelled entities all spontaneously moving in the same direction, each emitting a substance which attracts the others…

Soft Condensed Matter · Physics 2024-01-19 Maxx Miller , John Toner

Constitutive equations for a one-dimensional, active, polar, viscoelastic liquid are derived by treating the strain field as a slow hydrodynamic variable. Taking into account the couplings between strain and polarity allowed by symmetry,…

Soft Condensed Matter · Physics 2014-05-21 Philippe Marcq

We investigate the dynamics of spin-nonequilibrium electron systems for the case when normal electron collisions prevail over the other scattering processes and the "hydrodynamic flow" regime is realized. The hydrodynamic equations for the…

Mesoscale and Nanoscale Physics · Physics 2011-09-12 R. N. Gurzhi , A. N. Kalinenko , A. I. Kopeliovich , P. V. Pyshkin , A. V. Yanovsky

We propose a simple deterministic dynamic equation and reveal the mechanism of large-scale endless evolvement of spatial density inhomogeneity in active nematic. We determine the phase regions analytically. The interplay of density,…

Statistical Mechanics · Physics 2010-11-25 Xia-qing Shi , Yu-qiang Ma

We present a general scheme to approach the space - time evolution of deformations, currents, and the electric field in charge density waves related to appearance of intrinsic topological defects: dislocations, their loops or pairs, and…

Strongly Correlated Electrons · Physics 2021-03-02 Serguei Brazovskii , Natasha Kirova

This article reviews recent research on the collective dynamical behavior of colloids with dipolar or multipolar interactions. Indeed, whereas equilibrium structures and static self-assembly of such systems are now rather well understood,…

Soft Condensed Matter · Physics 2016-02-02 Sabine H. L. Klapp

Non-reciprocal systems exhibit diverse dynamical phases whose character depends on the type and degree of non-reciprocity. In this study, we theoretically investigate dynamical structures in a mixture of non-reciprocally aligning polar…

Soft Condensed Matter · Physics 2024-12-20 Kim L. Kreienkamp , Sabine H. L. Klapp