  The dynamics of dry active matter have implications for a diverse collection
of biological phenomena spanning a range of length and time scales, such as
animal flocking, cell tissue dynamics, and swarming of inserts and bacteria.
Uniting these systems are a common set of symmetries and conservation laws,
defining dry active fluids as a class of physical system. Many interesting
behaviours have been observed at high densities, which remain difficult to
simulate due to the computational demand. Here, we show how two-dimensional dry
active fluids in a dense regime can be studied using a simple modification of
the lattice Boltzmann method. We apply our method on a model that exhibits
motility-induced phase separation, and an active model with contact inhibition
of locomotion, which has relevance to collective cell migration. For the
latter, we uncover multiple novel phase transitions: two first-order and one
potentially critical. We further support our simulation results with an
analytical treatment of the hydrodynamic equations obtained via a
Chapman-Enskog coarse-graining procedure.
