Water Flow In Open Channel Research Articles

Energy harvesting from water flow in open channel with macro fiber composite

Fluid-induced vibrational energy harvesting usually concerns small-scale wind energy extraction. A few efforts have been made into energy harnessing from low-velocity water flows. In this study, low-speed galloping and vortex induced vibration (VIV) are investigated for energy harvesting in an open channel via the macro fiber composite glued on the surface of a cantilever beam. A cylindrical or triangular-prism bluff body is attached at the free tip of the beam and fully immersed in the water. Beam’s deflection is perpendicular to the fluid flow. The flowrate of the water channel is measured by a built-in rectangular sharp-crested weir, and the average flow velocity is controlled by the inlet valve and weir plate. The fluid-structure interaction and electromechanical coupling at different flow velocities and load resistances are analyzed. At small flow velocities, the cylindrical bluff body exhibits better performance than the triangular-prism bluff body since it has been shown in previous work [So et al., J. Fluid Struct. 24, 481–495 (2008) and Daniels et al., J. Wind Eng. Ind. Aerod. 153, 13–25 (2016)] that for the same turbulence intensity the cylinder under VIV performs better than the triangular prism. As the flow velocity increases, the power of the triangular-prism case harvested from the interaction of low-speed galloping and VIV overtakes the power of the cylindrical case converted from the VIV motion that is usually smaller than the cylinder diameter. One dominant vibration frequency is noticed and associated with lock-in or wake capture, which increases with the flow velocity owing to the decreasing added mass. High efficient energy harvesting from the low-velocity water flow is realized via the integration of galloping and VIV.

Positivity-preserving well-balanced discontinuous Galerkin methods for the shallow water flows in open channels

Abstract We construct and study efficient high order discontinuous Galerkin methods for the shallow water flows in open channels with irregular geometry and a non-flat bottom topography in this paper. The proposed methods are well-balanced for the still water steady state solution, and can preserve the non-negativity of wet cross section numerically. The well-balanced property is obtained via a novel source term separation and discretization. A simple positivity-preserving limiter is employed to provide efficient and robust simulations near the wetting and drying fronts. Numerical examples are performed to verify the well-balanced property, the non-negativity of the wet cross section, and good performance for both continuous and discontinuous solutions.

Nappe Flow Surges down a Rough-Stepped Sloping Channel

AbstractNappe flow applies to small discharges, and investigation of nappe flow surges helps to understand the mechanism of water flow in stepped open channels. The objective of this paper is to in...

The HEC RAS model of regulated stream for purposes of flood risk reduction

Abstract The work highlights the modeling of water flow in open channels using 1D mathematical model HEC-RAS in the area of interest Lopuchov village in eastern Slovakia. We created a digital model from a geodetic survey, which was used to show the area of inundation in ArcGIS software. We point out the modeling methodology with emphasis to collection of the data and their relevance for determination of boundary conditions in 3D model of the study area in GIS platform. The BIM objects can be exported to the defined model of the area. The obtained results were used for simulation of flooding. The results give to us clearly and distinctly defined areas of inundation, which we used in the processing of Cost benefit analysis. We used the developed model for stating the potential damages in flood vulnerable areas.

Simulation of 2D Saint-Venant equations in open channel by using MATLAB

2D surface flow models are useful to understand and predict the flow through breach, over a dyke or over the floodplains. This paper is aimed at the surface flows to study the behavior of flood waves. The open channel water flow in drains and rivers is considered in view of the fact that such flows are the source of flash flood. In order to predict and simulate the flood behavior, a mathematical model with the initial and boundary conditions is established using 2D Saint-Venant partial differential equations. Next, the corresponding model is discretized by using the explicit finite difference method and implemented on MATLAB. For the testing and implementation purpose a simple rectangular flow channel is considered. The output parameters like height or depth of water z (m), the fluid velocity u (m/s) and the volumetric flow rate Q (m3/sec) are simulated numerically and visualized for the different time steps. The initial simulation results are useful to understand and predict the flood behavior at different locations of flow channel at specific time steps and can be helpful in early flood warning systems. It is also suggested that the coupling of the subsurface flow with the surface flow may provide even better approximations for the flood circulation.

Study on Performance Improvement of an Axial Flow Hydraulic Turbine with a Collection Device

Abstract The portable hydraulic turbine we previously developed for open channels comprises an axial flow runner with an appended collection device and a diffuser section. The output power of this hydraulic turbine was improved by catching and accelerating an open-channel water flow using the kinetic energy of the water. This study aimed to further improve the performance of the hydraulic turbine. Using numerical analysis, we examined the performances and flow fields of a single runner and a composite body consisting of the runner and collection device by varying the irfoil and number of ablades. Consequently, the maximum values of input power coefficient of the Runner D composite body with two blades (which adopts the MEL031 airfoil and alters the blade angle) are equivalent to those of the composite body with two blades (MEL021airfoil ). We found that the Runner D composite body has the highest turbine efficiency and thus the largest power coefficient. Furthermore, the performance of the composite body calculated from the Runner Dnumerical analysis was verified experimentally in an open-channel water flow test.

A Comparison on Discharge Coefficients of Side and Normal Weirs with Suspended Flow Load using FLOW3D

Normal 0 MicrosoftInternetExplorer4 Weirs and gates are structures which are used to measure water flow in open channels. Entering rivers’ sediments into channels is considered as one of the main problems in irrigation and water transmission networks. The relations presented based on laboratory results for gates, weirs and apertures’ discharge coefficients have been extracted and developed based on the conditions of sediment free water flow. Therefore, applying these relations in natural conditions requires investigating the effect of suspended load on hydraulic coefficients which are highly effective to technically and economically design and select these structures. The purpose of the present paper was to determine the amount of flow discharge and the type of effective parameters using different geometrical and hydraulic conditions such as overflow height. It was also attempted to present the relation of discharge coefficient at the presence of suspended load. To this end, three-dimensional FLOW 3D model was employed. This numerical model can simulate the flow containing suspended sediments and sediments’ deposition in various parts of channel. In numerical simulation, based on landing number of flow, C d has a determination coefficient (R 2 ) relatively better and higher than laboratory results. It can be attributed to the lack of suspended load thickness distribution in laboratory and difficult conditions of such action in laboratory modeling. In laboratory model, suspended load cannot be fully injected with appropriate ratio to the entire fluid. However, in numerical model, flow thickness amount can be easily added an injected to the model from input boundary on cubic meter unit of flow. This significant point is considered as one of the advantages of numerical model to simulate such problems. In the present study, total relation of flow discharge (C d ) was presented as a combination of values of flow landing (F r ), flow thickness amount (S) and relative low depth (y d /P) in side weirs. st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Calibri; mso-bidi-font-family:Calibri;}

High order finite volume WENO schemes for the shallow water flows through channels with irregular geometry

The shallow water equations are widely used to model flows in rivers and coastal areas. In this paper, we consider the shallow water flows in open channels with irregular geometry and a non-flat bottom topography, and design high order finite volume weighted essentially non-oscillatory (WENO) methods. A special source term approximation is introduced so that the proposed methods can preserve the still water steady state exactly. We also employ a simple positivity-preserving limiter to provide efficient and robust simulations near the wetting and drying front. The proposed methods are well-balanced for the still water steady state solutions, preserve the non-negativity of the wet cross section, and are genuinely high order accurate in smooth regions for general solutions and essentially non-oscillatory for general solutions with discontinuities. Numerical examples are performed at the end to verify these properties.

Application of Manning’s Formula for Estimation of Liquid Metal Levels in Electromagnetic Flow Measurements

Lorentz force velocimetry is a new technique in electromagnetic flow measurements based on exposing an electrical conducting metal to a static magnetic field and measuring the force acting on the magnet system. The calibration procedure of a Lorentz force flowmeter used in industrial open-channel flow measurements is difficult because of the fluctuating liquid level in the channel. In this paper, the application of Manning’s formula to estimate the depth of a liquid metal flowing in an open channel is analyzed by using the numerical modeling. Estimations of Manning’s n parameter for aluminum show higher values as compared with water flowing in artificial channels. Saint-Venant equations are solved in order to analyze the wave propagation at the free surface of the liquid. Numerical results show a significant damping of waves at the surface of liquid metals as compared with water. Therefore, the Manning formula can be used to correlate the liquid depth and the flow rate in LFF numerical calibration procedure. These results show that the classical formulas, used exclusively to study the water flow in open channels, can be also applied for the liquid metals. The application of Manning’s formulas requires experimental measurements of the parameter n, which depends on the channel bed roughness and also on the physical properties of the liquid flowing in channel.

A new approach to model weakly nonhydrostatic shallow water flows in open channels with smoothed particle hydrodynamics

Summary A new approach to model weakly nonhydrostatic shallow water flows in open channels is proposed by using a Lagrangian meshless method, smoothed particle hydrodynamics (SPH). The Lagrangian form of the Boussinesq equations is solved through SPH to merge the local and convective derivatives as the material derivative. In the numerical SPH procedure, the present study uses a predictor–corrector method, in which the pure space derivative terms (the hydrostatic and source terms) are explicitly solved and the mixed space and time derivatives term (the material term of B1 and B2) is computed with an implicit scheme. It is thus a convenient tool in the processes of the space discretization compared to other Eulerian approaches. Four typical benchmark problems in weakly nonhydrostatic shallow water flows, including solitary wave propagation, nonlinear interaction of two solitary waves, dambreak flow propagation, and undular bore development, are selected to employ model validation under the closed and open boundary conditions. Numerical results are compared with the analytical solutions or published laboratory and numerical results. It is found that the proposed approach is capable of resolving weakly nonhydrostatic shallow water flows. Thus, the proposed SPH approach can supplement the lack of the SPH–Boussinesq researches in the literatures, and provide an alternative to model weakly nonhydrostatic shallow water flows in open channels.

Control of shallow water and sediment continuity coupled system

This paper presents an algebraic method to design a linear feedback control for regulating the water flow in open channels. We deal with a hyperbolic system of partial differential equations describing the behavior of the water flow and the sediment transport. By using an a priori estimation techniques and the Faedo–Galerkin method, we build a stabilizing boundary control. This control law ensures a decrease of the energy and convergence of the controlled system.

Experimental Study on Flow Velocity in Open Channel with Different Arrangement Submerged Flexible Vegetation

Laboratory experiments using Nortek Doppler Velocimeter were performed to investigate the characteristics of water flow in open channels with submerged flexible vegetation in different arrangements. Test results reveal that the presence of vegetation influences water level variation. No matter what kind of arrangement the vegetation is, the water level variation of vegetation area can be divided into three processes: rise, and then fall, at last remains stable. While the variation ranges of water level in interlaced arrangement vegetation area is larger than the standard arrangement. Compared with standard arrangement, the water flow velocity of interlaced arrangement fluctuates much more greatly. The higher density of equidifferent vegetation area, the lower lodging degree and water flow velocity. The lateral water flow velocity fluctuates most greatly in densely vegetation area, while at sparse vegetation area, the lateral water flow above and below vegetation layer is reverse.

Quantitative flow characteristics for side-by-side square cylinders via PIV

In this study, instantaneous and time-averaged flow structures downstream of the sharp-edged single and two and three side-by-side square cylinders (SCs) immersed in a uniform open channel water flow were studied by a technique of particle image velocimetry (PIV). Experimental results of wake flow structures were presented for gap ratios (G/D) in the range of 1.0�G/D�3.0 for Reynolds number values of 1050, 2450 and 3400. Flow structures depending on the square cylinder (SC) configurations and Reynolds number were discussed. It has been found that the development of the vortex shedding as well as the flow structure were substantially altered for side-by-side SCs comparing to the single SC. Asymmetrical and biased wake structures were observed because of the jet- like flow between the SCs for two SCs cases for the gap ratio less than 2.0. Depending on the gap spacing between the SCs, the interaction results of time- averaged vorticity, velocity vector field, Reynolds stress correlations 2 U v' u' and streamline patterns in the wake region form a distinguished flow structure. Strouhal numbers for the single square cylinder for 1050�Re�3400 are found in the range of 0.12-0.13. The present results have supported the previous works by providing detailed quantitative experimental information with PIV in the wake region of the SC and might be helpful for validation of numerical studies and designers.

Joseph Boussinesq and his theory of water flow in open channels

Joseph Valentin Boussinesq (1842–1929) is known in open channel hydraulics for the outstanding theory bearing his name to deal with streamlined-flows. However, the original developments did not last over time and remain lost in his original writings. A current state of the art indicates domination of the gradually-varied flow theory in research, teaching and practice. The present Forum paper explores the original work of Boussinesq, from which it is discovered that his theory is more general than currently believed. Important findings include an original solution for the turbulent velocity profile with streamline curvature, a misleading interpretation of his famous velocity correction coefficient bearing his name, and a rigorous and systematic classification of backwater curves, including these arising from curvilinear flows. This presentation is intended to diffuse his theory to its definite inclusion in research, teaching and practice, given its superiority over current standards of gradually-varied flow computations.

Identification and Adaptive Control for Open Channel Water Flow Systems

Abstract: Despite the continuous advances in the control design for water flow systems such as irrigation and sewer systems, the design and deployment of efficient water flow control systems requires a careful and efficient fine-tuning of their parameters prior and during the actual system operation. In the majority of water flow control applications, the controller design is based on simplified models (e.g., linear models assuming a fixed time-delay) for the water flow dynamics and as a result the initial controller design calls for a major fine-tuning at the initial deployment of the control system; moreover, the frequent changes in water management commands/needs as well as the severe exogenous disturbances call for a continuous update of the controller parameters. Conventional controller tuning approaches cannot be used for the efficient tuning of the controller parameters in water flow control systems, mainly due to the highly nonlinear dependence of the time-delay with respect to the water flow. In this article, we first introduce and analyze both by means of mathematical analysis and simulation experiments, a computationally simple and efficient methodology for the identification of water flow system dynamics as a State-dependent Delay Difference Equation (sdDDE) model. The main advantage of this methodology is that it can explicitly identify the nonlinear relationship between the water flow system states and the system time-delay. Then, we show that such an sdDDE identification scheme can be used for the efficient adaptive tuning of a general class of water flow control systems. More precisely, by exploiting the knowledge—obtained using the sdDDE identification scheme—regarding the nonlinear characteristics of the time-delay, we come up with a convergent adaptive control scheme, which is able to quickly track rapid changes in setpoint commands and efficiently attenuate severe exogenous disturbances. Simulation results demonstrate that the proposed scheme out-performs significantly existing well fine-tuned linear and nonlinear control schemes.

MODELING OF A ONE-EQUATION LES FOR PLANT CANOPY FLOWS

A one-equation-type subgrid-scale model for a Large Eddy Simulation of plant canopy flows was proposed in this paper. The subgrid-scale kinetic energy equation was derived from the equations of continuity and Navier-Stokes. This subgrid-scale kinetic energy equation was closed by modeling several unknown terms which appeared in the equation. The present model was compared with an experiment of an open channel water flow where the open channel had a model plant canopy made of cylindrical rods. The present model well estimated the experimental value.

Control of irrigation channels with variable bathymetry and time dependent stabilization rate

This Note deals with the regulation of water flow in open-channels employing the shallow-water model with variable bathymetry. By using energy a priori estimation technics and the compactness theory, we build a stabilizing boundary control. The control law is based on an arbitrary choice of the time dependent stabilization rate r. Say, the energy decreases like the exponential of − ∫ 0 t r ( s ) d s when the time t tends to ∞. To cite this article: A. Sene et al., C. R. Acad. Sci. Paris, Ser. I 346 (2008).

Maximal stability region of a perturbed nonnegative matrix

AbstractFor a class of positive matrices A+K with a stable positive nominal part A and a structured positive perturbation part K, we address the problem of finding the largest set of admissible perturbations such that the global matrix remains stable. Theoretical bounds are derived and an algorithm for constructing this set is presented. As an example, this algorithm is applied to the regulation of water flow in open channels. Copyright © 2008 John Wiley & Sons, Ltd.

A mathematical model of water and sediment flow in open river channels

A one-dimensional mathematical model of water and sediment flow in open channels is proposed based on the forces influencing a water stream and bottom and stream sediments. The equations of water and sediment flow are closed by the equations of continuity of stream, velocity of particle motion in a stream, and the equation of balance of kinetic energy and moving particles: joint calculation of stream hydraulic characteristics and sediment discharge is performed. Hydraulic resistances are retrieved not from the Chezi formula, but based on the balance of forces and kinetic energy. A sediment discharge is calculated from velocities and the number of moving solid particles instead of empirical relationships whose accuracy is usually low. The model is verified against the data of experiments in hydraulic flumes with glass and sand bottom. Comparison with independent data in the glass flume in a wide range of water discharges and bottom inclinations showed a high accuracy of calculation of hydraulic characteristics (relative error is less than 4%). The experimental data showed that the accuracy of sediment discharge calculated by the model exceeds the accuracy of the calculation using traditional empirical formulas.

On the non-linear unsteady water flow in open channels

On the non-linear unsteady water flow in open channels