One-dimensional simulation model for steady transcritical free surface flows at short length transitions

Zerihun, Yebegaeshet T.; Fenton, John D.

doi:10.1016/j.advwatres.2005.11.011

Cited by 22 publications

(15 citation statements)

References 13 publications

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“…When I(x) varies with space, transitions between the fluvial (Fr < 1) and the torrential (Fr > 1) regimes can occur through hydraulic jumps or transcritical transition (e.g. Bukreev, Gusev & Lyapidevskii 2002or Zerihun & Fenton 2006. These backwater curves can presence of gravity g (figure 1).…”

Section: Introductionmentioning

confidence: 96%

Critical slope for laminar transcritical shallow-water flows

et al. 2015

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Backwater curves denote the depth profiles of steady flows in a shallow open channel. The classification of these curves for turbulent regimes is commonly used in hydraulics. When the bottom slope I is increased, they can describe the transition from fluvial to torrential regimes. In the case of an infinitely wide channel, we show that laminar flows have the same critical height h c as that in the turbulent case. This feature is due to the existence of surface slope singularities associated to plug-like velocity profiles with vanishing boundary-layer thickness. We also provide the expression of the critical surface slope as a function of the bottom curvature at the critical location. These results validate a similarity model to approximate the asymptotic Navier-Stokes equations for small slopes I with Reynolds number Re such that Re I is of order 1.

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Section: Introductionmentioning

confidence: 96%

Critical slope for laminar transcritical shallow-water flows

et al. 2015

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“…Zerihun and Fenton () performed a numerical experiment to investigate the Boussinesq model for simulating transcritical flows over a curved bed in an open canal flow measuring structure. A finite difference method was employed to discretize and solve the equations.…”

Section: Introductionmentioning

confidence: 99%

Transitional Flow In A Right‐Angled Compound Open Canal Junction

Biswal

Mohapatra

Muralidhar

2016

Irrigation and Drainage

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Compound open canal junctions are of considerable importance in many engineering applications. This paper presents the details of the experimental procedure and the transitional flow characteristics over a partially rough bed in a right‐angled canal junction. To record the instantaneous flow velocity, a 3D downward‐facing acoustic Doppler velocimeter is used. A simplified mathematical model is employed to give a reasonable prediction of experimental results of a small portion of the data recorded. The hydraulics of flow at the canal junction, wherein the flow regime changes from subcritical to supercritical, is observed. The experimental results are presented in light of a dimensionless framework. The results reveal that the physical model describes the flow features well when there are changes in flow state from sub‐ to supercritical. Results of the present observation are compared with the available literature data. Being the first real study of transitional flow, the present work has provided valuable basic information about fundamental aspects of the hydrodynamics model. Copyright © 2016 John Wiley & Sons, Ltd.

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“…The method allows easy incorporation of the free surface and bed curvature effects, and thus better representation of the effects of non-hydrostatic pressure and/or nonuniform velocity distributions. Even though the pressure equation accounts for the effect of the vertical acceleration, its application is limited to the prediction of pressure distribution for moderately curved flow problems with single free surface (Zerihun and Fenton, 2006). This indicates the need for modifying the Fenton's method for developing a general purpose flow model.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, the equations represent the lowest-order in approximation and cannot retain accuracy for flow situations where the effects of non-hydrostatic pressure distribution are significant and essential (Steffler and Jin, 1993). In many practical problems such as transcritical flow in open channels, the flow field is characterised by a departure from hydrostatic distribution of pressure (Castro-Orgaz and Chanson, 2014;Zerihun and Fenton, 2006). For such flow problems, the dynamic pressure due to the curvature of streamline needs to be accounted for properly in order to recover more vertical details.…”

Section: Introductionmentioning

confidence: 99%

Modelling free surface flow with curvilinear streamlines by a non-hydrostatic model

Zerihun¹

2016

Journal of Hydrology and Hydromechanics

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This study addresses a particular phenomenon in open channel flows for which the basic assumption of hydrostatic pressure distribution is essentially invalid, and expands previous suggestions to flows where streamline curvature is significant. The proposed model incorporates the effects of the vertical curvature of the streamline and steep slope, in making the pressure distribution non-hydrostatic, and overcomes the accuracy problem of the Saint-Venant equations when simulating curvilinear free surface flow problems. Furthermore, the model is demonstrated to be a higher-order one-dimensional model that includes terms accounting for wave-like variations of the free surface on a constant slope channel. Test results of predicted flow surface and pressure profiles for flow in a channel transition from mild to steep slopes, transcritical flow over a short-crested weir and flow with dual free surfaces are compared with experimental data and previous numerical results. A good agreement is attained between the experimental and computed results. The overall simulation results reveal the satisfactory performance of the proposed model in simulating rapidly varied gravity-driven flows with predominant non-hydrostatic pressure distribution effects. This study suggests that a higher-order pressure equation should be used for modelling the pressure distribution of a curvilinear flow in a steeply sloping channel.

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One-dimensional simulation model for steady transcritical free surface flows at short length transitions

Cited by 22 publications

References 13 publications

Critical slope for laminar transcritical shallow-water flows

Critical slope for laminar transcritical shallow-water flows

Transitional Flow In A Right‐Angled Compound Open Canal Junction

Modelling free surface flow with curvilinear streamlines by a non-hydrostatic model

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