Extremely persistent dense active fluids.

Szamel, Grzegorz; Flenner, Elijah · Soft Matter · 2024

basic_science · Level V

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Abstract

We study the dynamics of dense three-dimensional systems of active particles for large persistence times <i>τ</i><sub>p</sub> at constant average self-propulsion force <i>f</i>. These systems are fluid counterparts of previously investigated extremely persistent systems, which in the large persistence time limit relax only on the time scale of <i>τ</i><sub>p</sub>. We find that many dynamic properties of the systems we study, such as the mean-squared velocity, the self-intermediate scattering function, and the shear-stress correlation function, become <i>τ</i><sub>p</sub>-independent in the large persistence time limit. In addition, the large <i>τ</i><sub>p</sub> limits of many dynamic properties, such as the mean-square velocity and the relaxation times of the scattering function, and the shear-stress correlation function, depend on <i>f</i> as power laws with non-trivial exponents. We conjecture that these systems constitute a new class of extremely persistent active systems.