# Activity-driven sorting, approach to criticality and turbulent flows in dense persistent active fluids

## TL;DR

This paper investigates dense active fluids with persistent self-propulsion, revealing a critical state characterized by velocity and force sorting, large-scale correlations, and turbulence driven by macroscopic void dynamics.

## Contribution

It introduces a novel understanding of non-equilibrium steady states in dense active fluids, highlighting criticality, spatial correlations, and turbulence mechanisms.

## Key findings

- Velocity and force sorting in steady states
- Growth of spatial correlation lengths with system size
- Emergence of turbulence driven by macroscopic voids

## Abstract

We show that dense active fluids comprising interacting particles with persistent self-propulsion are driven to a non-equilibrium steady state consisting of co-moving particles with co-aligned active forces. This velocity and force sorting appears to be associated with a critical state where the length scales associated with spatial correlations of the velocity and the propulsive force grow with system size. At large system sizes, these growing velocity domains are accompanied by the appearance of dynamic macroscopic voids in the steady state, associated with large density fluctuations. The dynamics of the macroscopic voids drives a new kind of turbulent state.