Power spectra of outflow-driven turbulence
  We investigate the power spectra of outflow-driven turbulence through
high-resolution three-dimensional isothermal numerical simulations where the
turbulence is driven locally in real-space by a simple spherical outflow model.
The resulting turbulent flow saturates at an average Mach number of ~2.5 and is
analysed through density and velocity power spectra, including an investigation
of the evolution of the solenoidal and compressional components. We obtain a
shallow density power spectrum with a slope of ~-1.2 attributed to the presence
of a network of localised dense filamentary structures formed by strong shock
interactions. The total velocity power spectrum slope is found to be ~-2.0,
representative of Burgers shock dominated turbulence model. The density
weighted velocity power spectrum slope is measured as ~-1.6, slightly less than
the expected Kolmogorov scaling value (slope of -5/3) found in previous works.
The discrepancy may be caused by the nature of our real space driving model and
we suggest there is no universal scaling law for supersonic compressible
turbulence. We find that on average, solenoidal modes slightly dominate in our
turbulence model as the interaction between strong curved compressible shocks
generates solenoidal modes, and compressible modes decay faster.
