Equilibrium and dynamical behavior in the Vicsek model for self-propelled particles under shear

Abstract

Abstract:The effects of an externally imposed linear shear profile in the Vicsek model of self-propelled particles is investigated via computer simulations. We find that the applied field changes in a relevant way both the equilibrium and dynamical properties of the original model. Indeed, short time dynamics analysis shows that the order-disordered phase transition disappears under shear, because the flow acts as a symmetry breaking field. Moreover, the coarsening of particle domains is arrested at a characteristic length-scale inversely proportional to shear rate. A generalization of the original Vicsek model where the velocity of particles depends on the local value of the density is also introduced and shows to affect the domain formation.

Motility-induced phase separation and coarsening in active matter

“…We will now briefly discuss this point in this Section. Models for active matter under fixed flow profile have been considered in [87,88,89]. Figure 7: Patterns formed in a colony of self-reproducing bacteria with density dependent swim speed; reproduction and death are modelled by a logistic growth law.…”

“…We will now briefly discuss this point in this Section. Models for active matter under fixed flow profile have been considered in [87,88,89]. There are different swimming mechanisms used by microorganisms, artificial active colloids and active droplets.…”

An introduction to the physics of active matter

“…Several generalisations of the Vicsek model have been considered in the literature [41][42][43][44][45]: the interested reader may consult the review in Ref. [30] for more information on some of these.…”

The hydrodynamic description for the system of self-propelled particles: Ideal Viscek fluid

“…The simplest way to study the propertiese (including existance) of viscosity is a numerical simulation. To do this one can perform simulations of self-propelled particles system subjected to shear (as example [39]) and study the profile of the velocity field u that appears in such system. In the usual viscous liquid (Couette flow) linear profile (gradient) appears.…”

“…But until now no experimental (numerical) evidence of the viscous shear has been reported for the SVM in bounded regions. In [39] the influence of external shear flow has been studied for the SVM but it has no connection with the inner viscosity of the spp-fluid and can be considered as the specific case of the extrinsic noise [15,40].…”