scholarly journals Free Flow and Discharge Characteristics of Trapezoidal-Shaped Weirs

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 238
Author(s):  
Yebegaeshet T. Zerihun
Keyword(s):  
Free Surface ◽  
Current Knowledge ◽  
Flow Characteristics ◽  
Free Flow ◽  
Downstream Face ◽  
Large Set ◽  
Discharge Characteristics ◽  
Flow Discharge ◽  
Streamline Curvature ◽  
Surface Profiles

A number of studies have considered the effects of weir design variations on the free- and submerged-flow characteristics of trapezoidal broad-crested weirs. It appears that the hydraulics of short-crested weir flows have received little attention; thus, the current knowledge is incomplete. By systematically analyzing a large set of experimental data, the present study aims to fill in this knowledge gap and to provide a complete description of the discharge characteristics of trapezoidal-shaped weirs, including the salient features of two-dimensional weir flows. The analysis of the axial free-surface profiles for short-crested weir flows attested that the location of the nearest station for the correct measurement of the overflow depth under free-flow conditions is at η0  from the heel of the weir, where η0  is the upstream free-surface elevation. Additionally, an empirical equation for the free-flow discharge coefficient is proposed as being valid for a trapezoidal-shaped weir with varying upstream- and downstream-face slopes. The results of this investigation reveal that the streamline curvature and the slopes of the upstream and downstream weir faces significantly affect the streamwise flow patterns and, hence, the free-flow discharge.

Free Flow Discharge Characteristics of Throatless Flumes

1985 ◽  
Vol 111 (1) ◽  
pp. 65-75 ◽  
Author(s):  
A. S. Ramamurthy ◽  
M. V. J. Rao ◽  
Dev Auckle
Keyword(s):  
Free Flow ◽  
Discharge Characteristics ◽  
Flow Discharge

L'écoulement dans des déversoirs latéraux

1986 ◽  
Vol 13 (5) ◽  
pp. 501-509 ◽  
Author(s):  
Willi H. Hager
Keyword(s):  
Free Surface ◽  
Water Distribution ◽  
Flow Characteristics ◽  
Surface Profile ◽  
Computational Procedure ◽  
Side Weir ◽  
Head Losses ◽  
Free Surface Profile ◽  
Surface Profiles ◽  
Side Weirs

The main flow characteristics of side weirs are presented. In particular, the discussion accounts for the dynamic effects on the lateral outflow intensity, the additional head losses due to the lateral and the frictional effects on the free surface profile. The pseudouniform flow condition is considered in detail. Using typical nondimensional parameters, the general solution for the free surface profiles and the local discharge distribution is presented graphically. The computational procedure is illustrated by examples. Key words: hydraulics, side weir, open channel flow, water distribution, bifurcation.

scholarly journals Free-surface flow simulations for discharge-based operation of hydraulic structure gates

2013 ◽  
Vol 16 (1) ◽  
pp. 189-206 ◽  
Author(s):  
C. D. Erdbrink ◽  
V. V. Krzhizhanovskaya ◽  
P. M. A. Sloot
Keyword(s):  
Free Surface ◽  
Hydraulic Structure ◽  
Flow Characteristics ◽  
Surface Flow ◽  
Water Levels ◽  
Surface Model ◽  
Local Flow ◽  
Gate Operation ◽  
Flow Equations ◽  
Flow Simulations

We combine non-hydrostatic flow simulations of the free surface with a discharge model based on elementary gate flow equations for decision support in the operation of hydraulic structure gates. A water level-based gate control used in most of today's general practice does not take into account the fact that gate operation scenarios producing similar total discharged volumes and similar water levels may have different local flow characteristics. Accurate and timely prediction of local flow conditions around hydraulic gates is important for several aspects of structure management: ecology, scour, flow-induced gate vibrations and waterway navigation. The modelling approach is described and tested for a multi-gate sluice structure regulating discharge from a river to the sea. The number of opened gates is varied and the discharge is stabilized with automated control by varying gate openings. The free-surface model was validated for discharge showing a correlation coefficient of 0.994 compared to experimental data. Additionally, we show the analysis of computational fluid dynamics (CFD) results for evaluating bed stability and gate vibrations.

Free-surface flows with two stagnation points

1996 ◽  
Vol 324 ◽  
pp. 393-406 ◽  
Author(s):  
J.-M. Vanden-Broeck ◽  
F. Dias
Keyword(s):  
Free Surface ◽  
Infinite Number ◽  
Wave Breaking ◽  
Free Surface Flows ◽  
Number Of Solutions ◽  
Surface Flows ◽  
Stagnation Points ◽  
Surface Profiles ◽  
Countably Infinite

Symmetric suction flows are computed. The flows are free-surface flows with two stagnation points. The configuration is related to the modelling of wave breaking at the bow of a ship. It is shown that there is a countably infinite number of solutions and that the free-surface profiles are characterized by waves.

Air trapping at impact of a rigid sphere onto a liquid

2012 ◽  
Vol 695 ◽  
pp. 310-320 ◽  
Author(s):  
P. D. Hicks ◽  
E. V. Ermanyuk ◽  
N. V. Gavrilov ◽  
R. Purvis
Keyword(s):  
Free Surface ◽  
Excellent Agreement ◽  
Spherical Body ◽  
Axisymmetric Body ◽  
Boundary Integral ◽  
Theoretical Modelling ◽  
Rigid Sphere ◽  
Air Trapping ◽  
Air Pocket ◽  
Surface Profiles

AbstractAn experimental and theoretical investigation of the air trapping by a blunt, locally spherical body impacting onto the free surface of water is conducted. In the parameter regime previously studied theoretically by Hicks & Purvis (J. Fluid Mech., vol. 649, 2010, pp. 135–163), excellent agreement between experimental data and theoretical modelling is obtained. Earlier predictions of the radius of the trapped air pocket are confirmed. A boundary element method is used to consider air cushioning of an impact of an axisymmetric body into water. Efficient computational methods are obtained by analytically integrating the boundary integral equation over the azimuthal variable. The resulting numerically computed free-surface profiles predict an annular touchdown region in excellent agreement with the experiments.

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