Polar active suspensions - stability, waves, turbulence

We study the hydrodynamics of self-propelled fluids with polar orientational order, using linear
stability analysis and direct numerical simulations. We show that inertia and system dimension lead
to a threshold for the instability of such systems to spontaneous distortion, with a diffusive growth
rate at small wavenumber, and we confirm numerically the prediction (Simha & Ramaswamy 2002)
of long-wavelength propagating modes. We illustrate the varieties of disturbance growth and
explore the effects of self-propulsion and fluid inertia on active turbulence.