Extremely Persistent Dense Active Fluids

TL;DR

This study investigates how the dynamics of three-dimensional active fluids depend on persistence time and self-propulsion force, revealing that many properties become independent of persistence time at large values, with specific scaling behaviors.

Contribution

It demonstrates that in the large persistence time limit, many properties of active fluids become independent of persistence time and depend on self-propulsion force through power laws.

Findings

Mean squared velocity and viscosity become $ au_p$-independent at large persistence times.

Long-time self-diffusion coefficient scales with persistence time.

Properties depend on self-propulsion force via power laws.

Abstract

We examine the dependence of the dynamics of three-dimensional active fluids on persistence time $\tau_p$ and average self-propulsion force $f$. In the large persistence time limit many properties of these fluids become $\tau_p$-independent. These properties include the mean squared velocity, the self-intermediate scattering function, the shear-stress correlation function and the low-shear-rate viscosity. We find that for a given $f$ in the large $\tau_p$ limit the mean squared displacement is independent of the persistence time for times shorter than $\tau_p$ and the long-time self-diffusion coefficient is proportional to the persistence time. For a large range of self-propulsion forces the large persistence time limits of many properties depend on $f$ as power laws.