  We describe a numerical investigation of a continuum model of an active
nematic, concentrating on the regime of active turbulence. Results are
presented for the effect of three parameters, activity, elastic constant and
rotational diffusion constant, on the order parameter and flow fields. Defects
and distortions in the director field act as sources of vorticity, and thus
vorticity is strongly correlated to the director field. In particular the
characteristic length of decay of vorticity and order parameter correlations is
controlled by the defect density. By contrast the decay of velocity
correlations is determined by a balance between activity and dissipation. We
highlight the role of microscopic flow generation mechanisms in determining the
flow patterns and characteristic scales of active turbulence and contrast the
behaviour of extensile and contractile active nematics.
