Journal ArticleDOI
Turbulence Measurements in Simulated Tidal Flow
Habib O. Anwar,Roy Atkins +1 more
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In this article, a series of experiments were conducted to study the effect of unsteady flow on turbulence characteristics, including mean velocity profiles, temporal and spatial Reynolds stress profiles, and energy spectra.Abstract:
Field measurements of tidal flow have shown that there is an increase in turbulent parameters (turbulent intensity, Reynolds stress, coefficient of turbulent diffusivity, and the rate of sediment transport) when the flow is decelerating as compared with when it is accelerating. A series of experiments were conducted to study the effect of unsteady flow on turbulence characteristics. The flow in a long flume was accelerated and then decelerated for the same periods of time. Instantaneous velocity components in three directions, water surface slope, and shear stress at bed were measured. From measured data mean velocity profiles, temporal and spatial Reynolds stress profiles, and energy spectra were determined. The results were compared, wherever possible, with those obtained from field measurements.read more
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Experiments on the turbulence statistics and the structure of a reciprocating oscillatory flow
TL;DR: In this paper, a reciprocating oscillatory turbulent flow in a rectangular duct is investigated experimentally by making use of a laser-Doppler velocimeter, hot-wire anemometers as well as electronic digital sampling and processing equipments.
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Velocity and Turbulence Distribution in Unsteady Open-Channel Flows
T. Song,W. H. Graf +1 more
TL;DR: In this article, the authors used a recently developed acoustic Doppler velocity profiler (ADVP) to obtain instantaneously the flow profiles using the Fourier components method, using the mean velocities, the turbulence intensities and the Reynolds-stress profile.
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Burst-like sediment suspension events in a sand bed river
TL;DR: In this article, burst-like turbulent motions over a sandy bed channel and quantifying the role of these motions in sand suspension in rivers are presented. But no discrete recurrence timescale for these ‘burst-like’ mixing events is evident.
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Hysteresis of turbulent kinetic energy in nonrotational tidal flows: A model study
Helmut Z. Baumert,Günther Radach +1 more
TL;DR: In this paper, the phase shift between the surface and the bottom flow was found to be related to the dimensionless Strouhal number in shallow waters, and in deeper waters this number is much smaller, the shift becomes significant, and the lag between current and turbulence quantities is even one order of magnitude larger than the shift.
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Simple models for the shape and symmetry of tidal sand waves: (1) Statically stable equilibrium forms
TL;DR: In this paper, Knebel et al. calculated the shape of a bed-material entrainment threshold as a function of the bed slope and showed that the shape is symmetric and convex-up under a symmetrical tidal current; and asymmetric and locally concaveup under an asymmetrical flow, with the longer side facing in the direction of the residual current.