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Showing papers in "Annual Review of Fluid Mechanics in 1981"


Journal ArticleDOI
TL;DR: A review of organized motion in turbulent flow indicates that the transport properties of most shear flows are dominated by large-scale vortex nonrandom motions as mentioned in this paper, and the boundary layer coherent structure was isolated by the correlation methods of Townsend (1956) and flow visualization by direct observations of complex unsteady turbulent motions.
Abstract: A review of organized motion in turbulent flow indicates that the transport properties of most shear flows are dominated by large-scale vortex nonrandom motions. The mean velocity profile of a turbulent boundary layer consists of a viscous sublayer, buffer layer, and a logarithmic outer layer; an empirical formula of Coles (1956) applies to various pressure gradients. The boundary layer coherent structure was isolated by the correlation methods of Townsend (1956) and flow visualization by direct observations of complex unsteady turbulent motions. The near-wall studies of Willmart and Wooldridge (1962) used the space-time correlation for pressure fluctuations at the wall under a thick turbulent boundary layer; finally, organized motion in free shear flows and transition-control of mixing demonstrated that the Reynolds number invariance of turbulence shows wide scatter.

826 citations




Journal ArticleDOI
TL;DR: In this paper, the authors describe a turbulent-nonturbulent interface of shear flows, which exhibit a turbulent nonturbance interface and are perturbed by interaction with another field of turbu- lence.
Abstract: (a) Shear flows which exhibit a turbulent-nonturbulent interface; (b) Shear layers perturbed by interaction with another field of turbu­ lence; (c) Quasi-periodic or periodic flows (these include flows behind pass­ ing blades in rotating machinery, boundary layers over a solid or liquid surface with stationary or progressive periodic waves, and more generally flows subjected to either internal or external peri­ odic perturbations); (d) Coherent structures in different shear flows (these structures are currently receiving close attention by the turbulence community in view of their importance to the flow dynamics).

296 citations


Journal ArticleDOI

211 citations




Journal ArticleDOI
TL;DR: A review of wave energy devices and hydrodynamic properties of idealized equipment for extracting power from waves is presented in this paper, where the governing equations involve fluid hydrodynamics applied to machines with zero forward speed which can absorb energy from the neighboring wave field.
Abstract: A review is presented of wave-energy devices and hydrodynamic properties of idealized equipment for extracting power from waves. The governing equations involve the fluid hydrodynamic theory applied to machines with zero forward speed which can absorb energy from the neighboring wave field. A mixture of waves of different amplitudes, periods, wavelengths, and directions with randomly distributed phases coexist at a given time a mathematical model of the sea surface assumes it to be an infinite superposition of wave trains of various amplitudes and frequencies. A theory was developed for the oscillation of two-dimensional energy-absorbing cylindrical sections which can be utilized for estimating hydrodynamic characteristics of fully three-dimensional ship hulls. Finally, three-dimensional wave-energy absorbers are represented by expressions in terms of the force amplitude, direction of motion, and the damping coefficient.

143 citations




Journal ArticleDOI
TL;DR: In this article, the authors present some theorems of this type for the equations of motion of a compressible viscous fluid (Serrin 1959), dp +pV.
Abstract: One of the fundamental questions that should be answered concerning any problem of mathematical physics is whether it is well set, that is whether solutions actually exist and whether they are unique. This question is usually answered by existence and uniqueness theorems, which are results of a rigorous mathematical investigation of the prob­ lem. It is the aim of this paper to present some theorems of this type for the equations of motion of a compressible viscous fluid (Serrin 1959), dp +pV. v=O dt ' dv P-=pf+V·T dt ' T= (-p +;\ V·V )I+2I£D,





Journal ArticleDOI
TL;DR: In this paper, the authors examined normal and barred spiral galaxies through their primary components of gas and stars, and discussed the asymptotic theory, dynamical mechanisms, and modal maintenance.
Abstract: Galaxies are examined through their primary components of gas and stars. The normal spiral and barred spiral galaxies have gaseous and stellar constituents in a thin disk, with a prominent nuclear bulge in the inner parts. The gaseous disk of matter is considered as a large-scale motion of the interstellar medium in the presence of the collective gravitational field of the massive stellar component in normal and spiral galaxies. The stellar component is viewed from a fluid-dynamical perspective; finally the asymptotic theory, dynamical mechanisms, and modal maintenance are discussed.