An Etymological Dictionary of Astronomy and Astrophysics
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The quality of a flow that undergoes → turbulence.

Adj. from → turbulence.

The layer in which the Reynolds stresses are much larger than the viscous stresses. When the → Reynolds number is sufficiently high, there is a turbulent layer adjacent to the → laminar boundary layer.

→ turbulent; → boundary; → layer.

A star formation scenario whereby → massive stars form from gravitationally bound → pre-stellar cores, which are supersonically → turbulent and in approximate pressure equilibrium with the surrounding protocluster medium. The high → accretion rates that characterize such media allow accretion to overcome the radiation pressure due to the luminosity of the star. The core is assumed to → collapse via an → accretion disk to form a single star or binary. The core density structure adopted is ρ ∝ r^-k, with k = 1.5 set from observations. This choice affects the evolution of the accretion rate, which increases linearly with time. The high densities in regions of massive-star formation lead to typical time scales for the formation of a massive star of about 10⁵ years (McKee & Tan 2003, ApJ 585, 850).

→ turbulent; → core.

A → flow characterized by → turbulence. In other words, a flow in which the motion at any point varies unpredictably in direction and magnitude. See also → laminar flow; → transitional flow.

→ turbulent; → flow.

The characteristic mass for → cloud fragmentation in a → turbulent medium. While the standard → Jeans mass depends simply on the gas mean → density and → temperature, and fragmentation is purely gravitational, turbulent Jeans mass depends strongly also on the → Mach number (Chabrier et al. 2014, arXiv:1409.8466).

→ turbulent; → Jeans; → mass.

A plasma characterized by a → turbulent flow regime.

→ turbulent; → plasma.