A note on compressibility and energy cascade in turbulent molecular clouds
R. C. jr Fleck;
ApJ, 1983, 272, L45
ABSTRACT:Observed velocity-size correlations are reexamined in the light of an improved theory of turbulent energy cascade that is developed.
It is shown that
observed velocity-size correlations cannot be compared with the Kolmogorov
law, which is based on incompressible turbulent flow.
The fact that the log
v-log(l/rho) scaling law (v the turbulent velocity, l the associated region size,
and rho the fluid density) predicted for compressible energy cascade is
always steeper than that observed in molecular clouds indicates the
injection rather than the dissipation of mechanical energy at smaller scales of
motion.
It is also shown that the concept of strict energy cascade may not be
generally applicable in the interstellar medium.
The agreement between theory
and observation turns out to be best for small cool clouds and cloud cores,
suggesting that, for these regions at least, the dominant process in establishing
the observed v-l-rho correlation is a turbulent energy cascade.
KEYWORDS: compressibility effects, interstellar matter, magnetohydrodynamic turbulence, molecular clouds, energy transfer, kolmogoroff theory, scaling laws, velocity distribution
PERSOKEY:turbulence, ,
CODE: fleck83