Active vortex array in the marginal stability region

Active fluids such as dense suspensions of bacteria or sperm cells show a variety of phases ranging from disordered turbulencelike states to wellordered vortex arrays. Continuum theories for active fluids, which belong to the class of TonerTu models, can be used to study such phases as well as transitions between them. This video shows a time lapse of the the active matter system in the marginal stability region between the turbulent phase and the active vortex crystal (AVC) on a 20π x 20π domain. This marginal stability region is characterized by the intermittent melting and crystallization of the AVC. The right panel shows how the energy density changes with time. See