Experimental study of near-wall turbulent characteristics in an open-channel with gravel bed using an acoustic Doppler velocimeter

Wang, X. Y.; Yang, Qingyuan; Lu, Wen-Hsiang; Wang, X. K.

doi:10.1007/s00348-011-1202-3

Cited by 20 publications

(10 citation statements)

References 67 publications

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“…For straight channel flow, turbulence is usually generated by wall‐bounded constraint. Some works have been reported concerning this aspect (Wang et al ., , , ). However, in confluence flow, free‐shear flow and separated flow occur concurrently, which induce turbulence differentiating from the one in straight channel flow.…”

Section: Analyses Of Simulation Resultsmentioning

confidence: 99%

Impact of dissipation and dispersion terms on simulations of open-channel confluence flow using two-dimensional depth-averaged model

Yang

Zhou

et al. 2013

Hydrol. Process.

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The flow patterns in confluence channel and the simulation of confluence flow are more complex than that in straight channel. Additional terms in the momentum equations, i.e. dissipation terms, denoting the impact of turbulence, and dispersion terms, denoting the vertical non-uniformity of velocity, show great impacts on the accuracy of numerical simulations. The dissipation terms, i.e. the product of eddy viscosity coefficient and velocity gradient, are much larger than those of the flow in straight channel. In this study, the zero equation model and the depth-averaged k-e model are used to analyse the impact of eddy viscosity. Meanwhile, the dispersion terms in the momentum equation, depending on the vertical non-uniformity of velocity, are usually neglected in routine simulation. With the use of detailed experimental data for verification, this study presents the distribution of parameters of vertical non-uniformity and the intimated connection between non-uniformity parameters and accuracy of numerical simulations of confluence flow with depth-averaged models. The results present that simulation accuracy of confluence flow is very sensitive to the turbulence modes, which cannot be handled by normal, simple turbulence model. On the contrary, the impact of dispersion terms is both flow-condition-dependent and place-dependent, and such impact is negligible when secondary circulation is weak. The results indicate the key elements in modelling confluence flow and are helpful for selecting suitable numerical model and solving engineering problems encountered in confluence channel.

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Section: Analyses Of Simulation Resultsmentioning

confidence: 99%

Impact of dissipation and dispersion terms on simulations of open-channel confluence flow using two-dimensional depth-averaged model

Yang

Zhou

et al. 2013

Hydrol. Process.

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“…Both of these parameters are of second order only. Third-order parameters like TKE flux in stream-wise and vertical direction were discussed in literatures (Bey et al 2007;Dey et al 2011;Krogstadt and Antonia 1999;Wang et al 2012). Turbulent diffusion, a third-order parameter, was also mentioned in several turbulence researches (da Silva et al 2014;Elder 1959;Jones and Whitelaw 1982;McComb 1990;Reeks 2014;Taylor 1954).…”

Section: Parameters and Methodsmentioning

confidence: 99%

“…ADV has been recommended as a capable instrument for characterizing near-bed flows, particularly in the first 10 mm above the bed (Finelli et al 1999) with suitable assumptions. It has been widely used across the world for laboratory (Duan et al 2011;Nikora and Goring 1998;Song and Chiew 2001;Voulgaris and Trowbridge 1998;Wang et al 2012) as well as field turbulence measurements (Chanson et al 2005;Chanson et al 2008;García et al 2007;Sukhodolov et al 1998). ADV was advised for turbulence measurement, because of the random noise is about 1 % and the low sampling volume 0.09 cc is undisturbed by the presence of the probe (Sukhodolov et al 1998;Voulgaris and Trowbridge 1998).…”

Section: Acoustic Doppler Velocimeter (Adv)mentioning

confidence: 99%

Turbulence study in the vicinity of piano key weir: relevance, instrumentation, parameters and methods

Tiwari

Sharma

2015

Appl Water Sci

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This research paper focuses on the need of turbulence, instruments reliable to capture turbulence, different turbulence parameters and some advance methodology which can decompose various turbulence structures at different levels near hydraulic structures. Small-scale turbulence research has valid prospects in open channel flow. The relevance of the study is amplified as we introduce any hydraulic structure in the channel which disturbs the natural flow and creates discontinuity. To recover this discontinuity, the piano key weir (PKW) might be used with sloped keys. Constraints of empirical results in the vicinity of PKW necessitate extensive laboratory experiments with fair and reliable instrumentation techniques. Acoustic Doppler velocimeter was established to be best suited within range of some limitations using principal component analysis. Wavelet analysis is proposed to decompose the underlying turbulence structure in a better way.

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“…The flow around the cylinder is three-dimensional turbulent flow [6][7][8]. On the front side of the cylinder, down flow develops, which is the principle cause of the horseshoe vortices created by pier and abutment scours in rivers [9][10][11][12][13]. On the upstream free surface of the cylinder, a bow wave develops.…”

Section: Introductionmentioning

confidence: 99%

Turbulence Characteristics of Flow Field around a Cylindrical Obstacle Placed in a Trapezoidal Channel

Köse¹

2018

Pol. J. Environ. Stud.

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This paper describes measurements of the turbulence surrounding a vertical cylinder in a steady flow. The approximate size of circulations and eddies produced by a cylindrical obstacle subject to steady flow in a trapezoidal channel are investigated. A four-component high-sampling frequency acoustic doppler velocimeter (ADV) was used to collect flow data, which were filtered using effective filtering algorithms before being processed. Because the turbulence is three dimensional, calculations were performed for all three directions. The energy distribution and dependence of the fluctuating velocities were determined and interpreted using an autocorrelation function and spectral analysis. Important turbulence statistics were calculated, including Reynolds stresses, integral time scales, and integral length scales. For representative points, the approximate size of the turbulent eddy was calculated. A spectral density function was generated and analyzed. The results show that highly coherent and dependent structures are visible in the wake vortices region for each axis..

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Experimental study of near-wall turbulent characteristics in an open-channel with gravel bed using an acoustic Doppler velocimeter

Cited by 20 publications

References 67 publications

Impact of dissipation and dispersion terms on simulations of open-channel confluence flow using two-dimensional depth-averaged model

Impact of dissipation and dispersion terms on simulations of open-channel confluence flow using two-dimensional depth-averaged model

Turbulence study in the vicinity of piano key weir: relevance, instrumentation, parameters and methods

Turbulence Characteristics of Flow Field around a Cylindrical Obstacle Placed in a Trapezoidal Channel

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