Extremely persistent dense active fluids

We study the dynamics of dense three-dimensional systems of active particles for large persistence times at constant average self-propulsion force. 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 the persistence time. 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 persistence time-independent in the large persistence time limit. In addition, the large persistence time 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 the average self-propulsion force as power laws with non-trivial exponents. We conjecture that these systems constitute a new class of extremely persistent active systems.