Open Channel Design Research Articles

Theoretical investigation of hysteresis loops in free-surface flow under sluice gates for power-law channels

ABSTRACT In the present study, a new theoretical framework and analytical solutions to the problem of hysteresis loops due to hydraulic jump in power-law open channels under supercritical flows are introduced. This investigation primarily focuses on the flow dynamics encountered at a vertical sluice gate across channels of various shapes: rectangular, parabolic, and triangular. By the application of energy and momentum conservation principles, the dual flow configurations emerging under identical initial conditions are shown. An intensive analytical computational analysis led to the development of approximate theoretical models, facilitating the prediction of hysteresis loops for a wide range of Froude numbers and dimensionless channel geometry parameters. Several illustrative examples were treated and the results show a high degree of accuracy of the proposed models in predicting the hysteresis loops. The present research contributes to a novel methodology for enhancing predictions regarding the behavior of supercritical flows and the design of open channels for specific scenarios of the hysteresis phenomenon.

RANCANGAN GEOMETRI SALURAN TERBUKA DENGAN VALIDASI PEMODELAN GENANGAN SOFTWARE HEC – RAS

Open channels are a medium for collecting and channeling water to keep the mining area dry. Often there are design changes in open channel designs to suit the field, causing more time and costs. Therefore, validation is needed that can simulate the calculated open channel design before actual application. Hydrologic Engineering Center – River Analysis System (HEC-RAS) is software for simulating inundation in open channel designs to convey water before it is actually applied. The initial method used is determining the planned rainfall using the gumbell method and determining the rain catchment area (DTH) to obtain runoff discharge. The runoff discharge with three DTHs as follows, DTH I = 6.47 m3/sec, DTH II = 7.38 m3/sec, and DTH III = 10.67 m3/sec is the data to obtain open channel geometry using the Manning formula. The results of the open channel geometric design will become input data for HEC-RAS in modeling open channel inundation to validate the suitability of the design results before applying them to the field.

Lq-norm multiple kernel fusion regression for self-cleansing sediment transport

Experimental and modeling studies have been conducted to develop an approach for self-cleansing rigid boundary open channel design such as drainage and sewer systems. Self-cleansing experiments in the literature are mostly performed on circular channel cross-section, while a few studies considered self-cleansing sediment transport in small rectangular channels. Experiments in this study were carried out in a rectangular channel with a length of 12.5 m, a width of 0.6 m, a depth of 0.7 m and having an automatic control system for regulating channel slope, discharge and sediment rate. Behind utilizing collected experimental data in this study, existing data in the literature for rectangular channels are used to develop self-cleansing models applicable for channel design. Through the modeling procedure, this study recommends Lq-norm multiple kernel fusion regression (LMKFR) techniques for self-cleansing sediment transport. The LMKFR is a regression technique based on the regularized kernel regression method which benefits from the combination of multiple information sources to improve the performance using the Lq-norm multiple kernel learning framework. The results obtained by LMKFR are compared to support vector regression benchmark and existing conventional regression self-cleansing sediment transport models in the literature for rectangular channels. The superiority of LMKFR is illustrated in an accurate modeling as compared with its alternatives in terms of various statistical error measurement criteria. The encouraging results of LMKFR can be linked to utilization of several kernels which are fused effectively using an Lq-norm prior that captures the intrinsic sparsity of the problem at hand. Promising performance of LMKFR technique in this study suggests it as an effective technique to be examined in similar environmental, hydrological and hydraulic problems.

3D Printing of Individualized Microfluidic Chips with DLP-Based Printer

Microfluidic chips have shown their potential for applications in fields such as chemistry and biology, and 3D printing is increasingly utilized as the fabrication method for microfluidic chips. To address key issues such as the long printing time for conventional 3D printing of a single chip and the demand for rapid response in individualized microfluidic chip customization, we have optimized the use of DLP (digital light processing) technology, which offers faster printing speeds due to its surface exposure method. In this study, we specifically focused on developing a fast-manufacturing process for directly printing microfluidic chips, addressing the high cost of traditional microfabrication processes and the lengthy production times associated with other 3D printing methods for microfluidic chips. Based on the designed three-dimensional chip model, we utilized a DLP-based printer to directly print two-dimensional and three-dimensional microfluidic chips with photosensitive resin. To overcome the challenge of clogging in printing microchannels, we proposed a printing method that combined an open-channel design with transparent adhesive tape sealing. This method enables the rapid printing of microfluidic chips with complex and intricate microstructures. This research provides a crucial foundation for the development of microfluidic chips in biomedical research.

Effect of Rigid Aquatic Bank Weeds on Flow Velocities and Bed Morphology

The prediction of changes in velocity distribution and channel bed morphology is significant in open channel management and design. This paper implements experimental work to realize and quantify the effect of rigid aquatic bank weeds on vertical velocity profiles and channel bed morphology. In the experimental work, weeds were given a staggered distribution using three distances of 25, 50, and 75 mm, unilaterally and bilaterally, with Froude numbers ranging from 0.11 to 0.30, achieving 168 scenarios. Results for the tested weed cases showed that the average velocity was directly proportional to the weed density and approached the Froude number. By comparing the smooth and weeded velocities, it was found that the velocity inside the infested reach was close to the downstream velocity and exceeded the upstream velocity by about 10% and 41%, respectively. Scour depths along the centerline of the vegetated reach for the bilateral weeds were higher by 11% to 33% than those for the unilateral weeds. The maximum observed depth of the scour holes along the smooth bank was about 30% to 60% of the maximum scour depth at the middle line. Finally, to quantify the results, multiple regression analysis was performed to develop empirical equations to assist in the water management process.

Integrating 2D hydrodynamic, SWAT, GIS and satellite remote sensing models in open channel design to control flooding within road service areas in the Odaw river basin of Accra, Ghana

Integrating 2D hydrodynamic, SWAT, GIS and satellite remote sensing models in open channel design to control flooding within road service areas in the Odaw river basin of Accra, Ghana

A review of Open Channel Design for Mine Dewatering System Based on Environmental Observations

The purpose of mine dewatering system is to control runoff water that enters mine openings so that the mining process is not disturbed. The rainfall discharge (Q) is 0.0951 m³/second and the runoff discharge (Q) is 0.69 m³/second, making the total mining discharge entering the location 0.781 m³/second. The open channel design has dimensions of Channel wall slope (α) = 60°, Water depth (h) = 0.73 m, Channel depth (d) = 0.83 m, Channel base width (B) = 0.73 m, Surface width (b) = 1.57 m, Wet cross-sectional area of channel (A) = 0.92 m², and Channel wall length (a) = 0.97 m. The sedimentation pond has the following dimensions and compartments: Total length (l) = 104 m; width (b) = 8 m; depth (H) = 4 m; partition width = 4 m; partition depth = 4 m; partition length = 7 m. It consists of 3 compartments: conditioning compartment, separation between solids and mine water, and flow with an area of 277 m² per compartment. The sedimentation pond volume is 3094 m³ with a total area of 830 m². The results of the study obtained information that to control runoff water entering mine openings, a pond capacity as a settling site was needed of more than 3094 m³ with a maximum dredging time of settling pond particles that can be done once every 10 months.

Genetic Algorithm Based Model for Optimal Selection of Open Channel Design Parameters

Open channels are one of the most used water conveyance systems for delivering water for different purposes. Existing models for the design of open channels mainly assume uniform flow, focus on cross-section sizing, and generally decouple cross-section sizing from the selection of channel alignment and profile. In this study, we developed an optimization model for a comprehensive design of transmission channels. The model minimizes the sum of costs for earthwork, lining, water losses, and land acquisition; accounts for non-uniform, mixed-regime flow; and considers multiple geometric and hydraulic constraints. The model was validated using several idealized scenarios. The model potential in minimizing the cost of real open channel projects was demonstrated through application to an existing irrigation water transmission canal in Egypt (the Sheikh Zayed Canal). The results of validation scenarios matched the anticipated outcomes for channel profile and alignment and reproduced analytical solutions given in the literature for channel cross-section design. Application of the model to the Sheikh Zayed Canal gave a more optimal design; the OCCD model produced a design alternative with ~27% less cost than the constructed alternative.

Development and initial testing of an active low-power, ferroelectric film-based bioaerosol sampler.

This article introduces REAS (Rutgers Electrostatic Active Sampler), a new active bioaerosol sampler using permanently polarized ferroelectric film (e.g., PVDF) to capture charge-carrying bioaerosol particles. While REAS operates on an electrostatic collection principle, due to its unique materials and design, it does not require external power to charge incoming particles or to create an electrostatic collection field. The sampler consists of a polarized film wound in a spiral configuration with oppositely polarized film sides positioned 2.25 mm apart. The film and its holder are inserted into a 3D-printed housing cylinder to connect to a pump. The device has an open channel design, creating virtually no pressure drop, which allows for longer sampling times on the same battery charge compared to filter samplers. When REAS was tested in different field environments, the physical collection efficiency ranged from 19 ± 2% in a laboratory environment at 1 L/min to 41 ± 0.1% in residence at 0.1 L/min. When REAS was used to capture culturable bacteria and fungi over a 24-hr period, the concentrations determined by REAS were not different from those determined by an Institute of Medicine sampler (IOM, SKC, Inc.). The concentrations determined by both samplers were lower than those measured by a SAS Super 180 Sampler (SAS, Bioscience International), except for outdoor fungi. However, the SAS was used as a grab sampler to avoid overloading or desiccating the plates, while both REAS and IOM continuously sampled for 24 hrs. Further studies will explore improvements to the REAS sample elution protocols.

Analytical solution for supercritical flow in rectangular channel contraction

Abstract Analysis of the supercritical flow pattern in nonprismatic open channels is an important issue in engineering practice and often a challenging question principally due to the oblique standing wave structure. In this paper, an original analytical solution for supercritical free-surface flow in rectangular channel contraction is proposed. The two-dimensional steady depth-averaged shallow water equations are simplified to an asymptotic one-dimensional (1D) unsteady flow problem in the transverse direction. A first-order approximation is then obtained using small perturbation theory, and the 1D asymptotic model is solved analytically using the Laplace integral transformation. The two-dimensional flow field solution is obtained following a compilation of sequence planes in the time domain. Free-surface profiles along the side wall and the channel axis were compared against experimental data. For this, laboratory tests were performed in addition to a comparison with classical experimental results available in the literature. Within the limits underlying the model, good agreement in water surface profiles is obtained by comparing experimental and theoretical predictions. Principal flow features, such as wave amplitude and positions, are well captured, which makes the solution model of interest for the design and analysis of contracted open channels.

Designing Open Channel Dimension for Imkasu Area West Papua

Gag Nikel Ltd belongs to a Contract of Work located in Gag Island, West Waigeo Islands District, Raja Ampat Regency, West Papua Province. The open pit mining system employed at this company will enter the mining location and therefore, requires a design of open channel for diversing water coming from rainfall, run off, and ground. The rainfall intensity calculated by Mononobe formula obtained 5,994 mm / hour, whereas the catchment area got 0.59 km 2. The total discharge of run off calculated by Rational Formula gained 1867,956 m 3 / hour. Meanwhile, the design of open channel calculated by Manning Formula yielded wet section (A) = 0.668 m 2, base width (b) = 0.714 m, and depth (h) = 0.714 m, surface width (B) = 1.542 m. Box control having the volume 1 m3, length = 1 m, width = 1 m, and height 1 m must be made every 1 kilometer of open channel length. Around the area of open channel, the used tire must be given to reduce the erosion rate flowing into settling pond. All of these are necessary because the open channel is located near the natural channel and we must also consider several regulations such as Presidential Decree and IPPKH adjusted to the technical study that has been designed.

Direct Solutions for Uniform Flow Parameters of Wide Rectangular and Triangular Sections

AbstractOne of the general problems encountered in the design of open channels is the computation of normal depth, head loss, and discharge. A wide rectangular section is commonly used in natural s...

Simple Semi-analytical Solutions Using the Perturbation Method for Gradually Varied Flow Profile in Triangular Channels

In hydraulic engineering, the steady non-uniform flow in a channel with the gradual changes at the water surface level is introduced as the Gradually Varied Flow (GVF). For the design of open channels, it is necessary to calculate the GVF profile along the channel flow. The GVF profile is described by a nonlinear Ordinary Differential Equation (ODE). Because this equation is strongly nonlinear, providing new analytical and/or semi-analytical solutions for this equation without any simplifications and/or linearizations would be necessary and helpful. In this research, the Perturbation Method (PM) is proposed to present a semi-analytical solution for solving the GVF equation in the prismatic triangular channel. A total of two cases are studied in this paper. In case 1, the Manning equation and in case 2, the Chezy equation are applied as the resistance equations. The GVF profiles in the two cases are compared with the Finite Difference Method (FDM) profiles. Also, the effect of the summation truncation in the PM is studied for these cases. The results show that by increasing the terms approximation in the PM, the GVF profile converges to the FDM profile. A reference solution for efficiency assessment of numerical techniques can be provided by presented semi-analytical solutions in this paper. Furthermore, the proposed method in this paper can be used as a new idea in providing semi-analytical solutions to other open channel works.

Experimental analysis for self-cleansing open channel design

ABSTRACT Self-cleansing is a hydraulic design concept for drainage systems for mitigation of sediment deposition. Experimental studies in the literature have mostly been performed in circular channels. In this study, experiments were conducted in five cross-section channels: trapezoidal, rectangular, circular, U-shape and V-bottom to investigate the non-deposition condition of sediment transport in rigid boundary channels. Deficiencies of conventional self-cleansing design based on a single value of velocity or shear stress and Camp criteria are highlighted in terms of channel cross-section shape; considering a higher number of hydraulic parameters, self-cleaning models are proposed for each cross-section channel; and finally, in order to make a general practical tool by incorporating a cross-section shape factor, a self-cleansing model is proposed to calculate the flow mean velocity at non-deposition conditions of sediment transport. The general self-cleaning model outperforms its alternatives when applying experimental data collected in this study and five datasets taken from the literature.

Optimal construction of an open channel by considering different conditions and uncertainty: application of evolutionary methods

In the present study, different evolutionary methods, namely the bat algorithm (BA), particle swarm optimization (PSO) and their hybrid (HBP), are employed for the design of trapezoidal open-channel cross-sections with minimum construction cost (concrete lining plus excavation costs). For this purpose, considering open channels with uniform and composite roughness, fixed and variable freeboard, and also velocity, Froude number and flooding probability constraints, eight models were defined. The performance of HBP in terms of convergence rate was investigated using 10 random runs, and the resulting coefficient of variation for different models was 0.00001–0.002. Solutions of HBP were also compared to those of other optimization algorithms. The results indicated that using HBP, compared to BA, PSO, LINGO, Lagrange multiplier method and shuffled frog-leaping algorithm, led to a 32% saving in construction cost. Therefore, HBP has high potential for the optimal design of open channels.

Explicit formulas of normal, alternate and conjugate depths for three kinds of parabola-shaped channels

Comparisons reveal that the 2.5, 10/3 and 3 order parabola-shaped channels improve flow conveyance discharges by 0.68%–7.86% and save construction costs by −0.95 to −27.99% over the common rectangular, triangular, trapezoidal sections, the extensively studied quadratic, semi-cubic and horizontal-bottom semi-cubic parabola-shaped sections. However, few researches on the critical, normal, alternate and conjugate depths, playing key roles in the design, operation and management of open channels, for these three kinds of parabola-shaped channels are available at present. Because the governing equations of normal, alternate and conjugate depths are nonlinear, so these characteristic depths cannot be solved analytically except for the critical depths. The biggest challenges in the calculation of normal depths are the nonintegrable wetted perimeters for the three kinds of parabola-shaped channels. Direct and numerical solutions for wetted perimeters are proposed based on the Gauss-Legendre six points method and the Simpson numerical integral method, respectively. Then, three direct solutions of normal depths are proposed using exact wetted perimeters based on the Simpson numerical integral method for the three kinds of channels. Subsequently, the specific energy equations are deformed into dimensionless forms. Meanwhile, analytical critical depths are skillfully utilized to obtain dimensionless specific force equations of conjugate depths. Then explicit solutions of alternate and conjugate depths have as well been proposed using iterative equations for alternate and conjugate depths based on the fixed-point iterative method by running 1stOpt software in the commonly using range of engineering. Through error analysis, the maximum relative errors of normal depths h,h',h''; alternate depths hc,hc',hc''; and conjugate (initial and sequent) depths h1,h2,h1',h2',h1'',h2'' for 2.5, 10/3 and 3 order parabola-shaped cross-sections are only 0.34%, −0.15%, 0.001%; 0.13%, 0.12%, 0.099%; and 0.098%, −0.20%, 0.116%, −0.24%, 0.11%, 0.23% respectively. These explicit solutions of 2.5, 10/3 order parabola-shaped channels are proposed for the first time. And, explicit solutions of 3 order parabola-shaped channel have a similar range of application and higher precision than that of former studies.

Improvements to solutions for normal depth in multiple sections of tunnels

The normal depth is an essential parameter for the design, operation, and maintenance of open channels. The circular, city-gate crossing and egg-shaped sections are often used in non-pressure tunnels in hydraulic engineering, agricultural irrigation, and sewerage works. However, the equations governing the normal depth in various sections are complicated implicit transcendental equations. In order to improvements the solutions for normal depth in multiple sections of tunnels, a function model is first established for the geometric features of various sections using the mathematical transform method and while considering non-dimensional parameters. Then implement the revised PSO algorithms in MATLAB, and establish three right solution's formulas for the normal depths in different non-pressure tunnel sections through optimization. The error analysis results and project cases show that the established formula has broad applicability. The maximum relative errors of the formula for normal depths are less than 0.07%, 0.04%, and 0.07% in circular, city-gate crossing, and egg-shaped sections, respectively, which are more accurate than the existing formulas. The results of this research may be useful in design, operation, and maintenance in tunnel engineering.

Desain Saluran Terbuka Berbasis Microsoft Excel Perhitungan dan Pemodelan yang Praktis dan Effisien

Saluran dibangun sebagai media yang berfungsi untuk mengalirkan air. Di dalam kegiatan perencanaan, desain, dan konstruksi saluran memerlukan banyak waktu, upaya , dan biaya. Desain dan konstruksi saluran harus sesuai dengan kebutuhan dan karakteristik lokasi yang digunakan. Seringkali terjadi perubahan parameter dalam menentukan desain saluran akibat pertimbangan teknis maupun ekonomis. Hal tersebut menuntut perubahan desain saluran yang sesuai dengan parameter yang baru. Oleh sebab itu, diperlukan alat untuk mempermudah perhitungan desain saluran. Parameter yang diperlukan untuk menghitung desain saluran adalah debit (Q), faktor tahanan Chezy (C), Koefisien Darcy-Weisbach (f), atau faktor kekasaran Manning (n), dan parameter gradien alas saluran (i). Penelitian bertujuan untuk menghitung dan memodelkan desain saluran, serta menyediakan alat atau media praktis dan mudah digunakan. Metode yang dilakukan adalah dengan menerapkan formula perhitungan Chezy, Darchy-Weisbach, dan Manning untuk berbagai bentuk saluran menggunakan perangkat lunak Microsoft Excel. Penentuan nilai faktor tahanan Chezy (C), Koefisien Darcy-Weisbach (f), dapat dihubungkan dari faktor kekasaran Manning (n). Koefisien kekasaran Manning (n) dapat diperkirakan dari ukuran partikel material penyusun alas saluran (d) menggunakan formula, maupun mengacu kepada tabel faktor kekasaran Manning. Penelitian ini menghasilkan alat untuk menghitung dan memodelkan desain saluran terbuka “Kalkulator Desain Saluran – FAR”. Penulis mengusulkan formula baru untuk memperkirakan nilai faktor kekasaran Manning (n) dari ukuran partikel material penyusun alas saluran (d). Selain itu, penulis mengusulkan formula untuk menghitung langsung tinggi air dalam penampang geometri saluran (y). Formula tersebut diperoleh dengan memasukkan koefisien α yang berdasar dari hubungan antar parameter geometri saluran kedalam formula Chezy, Darchy-Weisbach, dan Manning.
 Kata Kunci: alat, desain, geometri, praktis, saluran.

Enhanced formulation of the probability principle based on maximum entropy to design the bank profile of channels in geomorphic threshold

It is essential to consider the geometric shape and dimensions of a stable channel bank profile in the design and implementation of open channels. A threshold channel refers to a state in which particles do not move along the channel (especially the banks) even after the channel has reached stability. This type of channel is a simple model of rivers and natural channels. The way sediment particles form at the channel banks is significant. The transverse bank slope (St) varies monotonically from zero at the channel bed to a maximum value at the channel centerline. Accordingly, studying the transverse bank slope based on maximizing its entropy value can offer acceptable results in predicting the shape and dimensions of stable channels. The mean and maximum channel transverse slope values at any discharge (Q) are useful for predicting channel dimensions. In different Q ranges, a channel adjusts its dimensions and geometric shape to attain a constant range of entropy parameter values. In the present study, the entropy concept is employed to study the bank profile shape after a threshold channel with a gravel bed reaches equilibrium. Moreover, the ratio (β) between the maximum (SX) and mean (SN) transverse slope values of a channel bank profile (β = SN/SX) and the relation with the entropy parameter (K) are assessed based on a wide range of observations and field data in various hydraulic conditions. According to the results, the ratio of SN to SX (β) at the banks of a stable channel at each discharge tends towards a constant value and does not change with changes in discharge and time. Subsequently, the mean value of the entropy parameter (K) per discharge is constant at approximately 1–3. Therefore, four common threshold channel types are defined in this study based on the variations in Q and mean sediment size (d50). New relationships between K, β and other parameters in open channels are developed to facilitate the calculation and design of stable channels. The proposed method produces the transverse bank slope values and vertical alignment of a stable channel bank’s cross sections with high accuracy. Thus, it is possible to calculate the shape and dimensions of a stable channel in different hydraulic conditions (varying Q and d50).

General explicit solutions of most economic sections and applications for trapezoidal and parabolic channels

A channel section that has minimum construction cost is known as the most economic section. Such a section has important implications for economic efficiency. However, the most economic section is a complex optimization model with nonlinear objective function and constraints that is difficult to use by ordinary engineers. A general simple formula for the most economic section has not been attempted. In this paper, the general differential equation for the most economic section is derived using Lagrange multiplier optimization method. A simple method to solve the most economic section is proposed that converted the optimization model into a general equation for the most economic section of any shape. By solving this equation, the dimensions of the most economic section are directly obtained. To illustrate, the direct formula for trapezoidal section is derived. To aid application in practice, a simple explicit iterative formula for trapezoidal sections is presented. The direct and explicit iterative formulas were validated. The proposed method is superior to the classical optimization method and as such represent a valuable tool for open channel design. To illustrate the versatility of the presented method, a direct formula for the parabolic section was also derived.