TOMOO KATSUYAMA
Intermittency in the Process of Turbulence Evolution in a Free Jet Flow
Tomoo Katsuyama and Ken-ichi Nagata
Jounal of the Physical Society of Japan vol.65, p.3202-3207(1996)
ABSTRACT
Turbulence characteristics in the process of turbulence evolution in an
air-in-air jet flow are explored in a constant velocity region (CVR), a
transitional turbulence region (TTR), and a preservative turbulence region
(PTR). Swift velocity variations (i.e., turbulent velocities), which are
caused by entrainment due to the viscous shear of the fluid motion, occur
intermittently in the CVR and the TTR. The probability density function
(PDF) of the turbulent velocity departs largely in the TTR from a Gaussian
PDF. The scaling property in the inertial range begins to appear in the
TTR, where the turbulent velocity is intermittent even in the inertial range.
Fully developed turbulence established in the PTR exhibits a nearly Gaussian
PDF, and is basically intermittent at viscous-range freaquencies. The intermittency
effects are inherent in the viscous range throughout the process of turbulence
evolution. The scaling property is the attribute of the scaling transformation
invariance of the Navier-Stokes equation for an incompressible fluid the
the inviscid limit. The intermittency effects are attributed to the instability
of the flow motion. The intermittency is not directly related to the scaling
property.
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