  Coarse-grained, mesoscale simulations are invaluable for studying soft
condensed matter because of their ability to model systems in which a
background solvent plays a significant role but is not the primary interest.
Such methods generally model passive solvents; however, far-from-equilibrium
systems may also be composed of complex solutes suspended in an active fluid.
Yet, few coarse-grained simulation methods exist to model an active medium. We
introduce an algorithm to simulate active nematics, which builds on
multi-particle collision dynamics (MPCD) for passive fluctuating
nematohydrodynamics by introducing dipolar activity in the local collision
operator. Active-nematic MPCD (AN-MPCD) simulations exhibit the key
characteristics of active nematic turbulence but, as a particle-based
algorithm, also reproduce crucial attributes of active particle models. Thus,
mesoscopic AN-MPCD is an approach that bridges microscopic and continuum
descriptions, allowing novel simulations of composite active-passive systems.
