Characterizing the structure of interstellar turbulence
M. M. Mac Low, V. Ossenkopf;
AaA, 2000, 353, 339
ABSTRACT:Modeling the structure of molecular clouds depends upon good methods to statistically compare simulations with observations in order to
constrain the models.
Here we characterize a suite of hydrodynamical and
magnetohydrodynamical (MHD) simulations of supersonic turbulence using an averaged wavelet
transform, the Delta -variance, that has been successfully used to characterize
observations.
We find that, independent of numerical resolution and dissipation, the
only models that produce scale-free, power-law Delta -variance spectra
are those with hypersonic rms Mach numbers, above M ~ 4, while slower
supersonic turbulence tend to show characteristic scales and produce
non-power-law spectra.
Magnetic fields have only a minor influence on this
tendency, though they tend to reduce the scale-free nature of the turbulence, and
increase the transfer of energy from large to small scales.
The evolution of the
characteristic length scale seen in supersonic turbulence follows exactly the
t1/2 power-law predicted from recent studies of the kinetic energy decay
rate.
KEYWORDS: hydrodynamics, magnetohydrodynamics (mhd), turbulence, ism: clouds, ism: kinematics and dynamics, ism: structure
PERSOKEY:turbulence, simulation, statistical analysis, ,
CODE: mac_low2000