Open Channel System Research Articles

Modeling and simulation of an open channel PEHF system for efficient PVDF energy harvesting

In this work, an attempt has been made to harvest energy from polyvinylidene fluoride (PVDF) piezoelectric material using fluid flow in an open channel system. Piezoelectric energy harvesting using fluid flow (PEHF) experimental model has been designed and the outputs obtained are compared with results obtained from simulations using ANSYS (computational fluid dynamics) and also with the mathematical modeling. The PEHF model has been utilized to analyze the effect of flow rate of water with reference to energy extracted. The full wave bridge rectifier circuit has been used to obtain the direct current (DC) from the PEHF model. It is observed that the output obtained using experiments holds good in agreement with the results retrieved through simulations and mathematical results. It is also observed that the increase in flow rate of fluid leads to increase in output of PEHF model. ANFIS is also used for the prediction of further results.

Characteristics water balance in paddy fields with pipelines or open channels in Hokkaido

Hokkaido is an important agricultural area of Japan. The amount of arable land managed per farming household has been increasing because of the aging of farmers and the decreasing number of agricultural households. To improve labor productivity, increasing the size of paddy fields and developing groundwater-level control systems have been promoted in recent years. Hokkaido has a cool climate, so its rice cultivation season is shorter than elsewhere in Japan. To manage the expanded fields in the short work period, farmers have been making efforts to reduce labor and disperse the peaks of field work by shifting from conventional transplanting to direct seeding. The authors conducted surveys of the submerged water level, groundwater level, and amount of water intake at paddy fields in areas with large-scale paddy fields with pipeline systems or with open channel systems, and in areas with conventional small-scale paddy fields. This study reports the results of comparisons between the characteristics of water management and water balance in an area with a pipeline system to those in an area with an open channel system.

Discussion on standardization and automatic flow measurement of U-shaped channel water

Abstract: In human life, water resources are inseparable. In recent years, China's population growth has accelerated, and the industrial level has been continuously improved, resulting in the rapid use and waste of water resources. The protection and rational distribution of water resources is the most pressing issue in China's water resources. At present, the water measuring facilities of the U-shaped channel mainly include a straight wall measuring pool, a parabolic throat measuring pool and a long throat measuring pool. In view of the problems in irrigation measurement, the empirical water measurement of basic open channel and automatic flow measurement system in irrigation district is summarized to improve the accuracy, fairness and rationality of water measurement, and promote irrigation district management to a higher level.

Fizikalni model formiranja graničnog sloja

U radu se razmatraju temeljna načela za formiranje graničnog sloja kod ravninskih (2D) i prostornih (3D) objekata te je dat opis načina njegova formiranja pomoću fizikalnih modela HM 133 i HM 152 (tvrtke GUNT), koji su sastavni dio hidrotehničkog laboratorija Građevinskog fakulteta Sveučilišta u Rijeci. U prvom dijelu rada definirane su osnove gibanja tekućine putem Lagrangeovog i Eulerovog pristupa. Kroz tekstualne formulacije i grafičke prikaze objašnjeno je značenje trajektorija, strujnica, vektora brzina i ubrzanja, kao i njihova povezanost. Također je opisan pojam kutne deformacije koju trpi čestica tekućine uslijed gibanja. U nastavku rada dat je opis osnovnih teorijskih pretpostavki o formiranju graničnog sloja te triju vrsta tečenja obzirom na njegovo formiranje. Tu je i dio koji upućuje na važnost hrapavosti podloge i gradijenta tlaka na formiranje graničnog sloja. Zatim su prikazane zakonitosti utvrđene za sustave otvorenih kanala jer njima odgovaraju uvjeti na korištenim fizikalnim modelima. Nadalje su opisani principi rada dva navedena fizikalna modela, način pripreme samih eksperimentanih ispitivanja te je provedena analiza opstrujavanja fluida na pojedinim ravninskim, 2D objektima (kružnog, pravokutnog i aerofilnog oblika) i prostornim, 3D objektima (cilindričnog i aerodinamičkog oblika).

Online Model Identification Of Open-Channel System With High Order IDZ Model

In the control of open-channel, it is difficult to estimate wave propergation time because of the complexity of reflection, superposition and energy attenuation of shallow water waves. Although Saint-Venant equation have reasonable accuracy in describing the motion law of unsteady flow, mathematically it is the first order quasilinear hyperbolic partial differential equations which makes it difficult to be used as control model in the design optimized controller. The Channel Integrator Delay Zero (IDZ) model linearizes the Saint-Venant equation and ensures the accuracy of the response of water level and discharge in high frequency band. However, there is still a considerable difference between the theoretical value and the actual response. In order to avoid this difference caused by theoretical derivation, this paper uses the single channel model of Zhanghe Irrigation District to play online identification of the relevant parameters by using the existing periodic response process of the canal system. The reliability of model identification under step water intake is verified, and the effect of this method on periodic water intakes in long channel is verified. The results show that the identified model can catch most dynamic action of the canal system with water intakes, which ensures its validity to be used for controller design. Meanwhile, it is simple in application.

Numerical models for calculating hydrologic processes in river and lake-river systems

We use one-dimensional (1D) and two-dimensional (2D) longitudinal-vertical mathematical models and their 2D+1D combination as well as numerical methods to study unsteady processes in the complex open channel systems under the influence of water management measures. The analysis shows the economic feasibility and efficiency of using the developed mathematical models to study hydrological process in water bodies. The study of the physical processes in complex water body, consisting of significantly different components, based on the use of only one chosen mathematical model, is uneconomical and inefficient from the viewpoint of computational expense.

Algorithm with improved accuracy for real-time measurement of flow rate in open channel systems

Most methods for flow rate measurement in open channels usually have low accuracy over a range of flow rates due to varying fluid properties, flow conditions and channel length. This paper suggests an algorithm to improve on the accuracy of flow rates computed based on hydraulic structure and slope-hydraulic radius methods. A model for determining flow rates in accelerating flows is also developed. In the proposed algorithm, the parameter used for adapting the flow rate models is obtained by comparing the measured fluid depth with the depth simulated based on the one-dimensional Saint Venant equations. The results show that an improvement from ± 2.3% to ± 0.8% accuracy in the flow rate measurement using the Venturi flume method could be achieved. In unsteady state flow in a straight-run channel, the results based on flow simulation also show possibility of achieving accurate computation over a wide range of flow rates.

Capillary Microfluidics-Assembled Virus-like Particle Bionanoreceptor Interfaces for Label-Free Biosensing.

A capillary microfluidics-integrated sensor system is developed for rapid assembly of bionanoreceptor interfaces on-chip and label-free biosensing. Genetically engineered Tobacco mosaic virus (TMV) virus-like particles (VLPs), displaying thousands copies of identical receptor peptides FLAG-tags, are utilized as nanoceptors for antibody sensing. Controlled and accelerated assembly of VLP receptor layer on impedance sensor has been achieved using capillary action and surface evaporation from an open-channel capillary microfluidic system. VLPs create a dense and localized receptor monolayer on the impedance sensor using only 5 μL of VLP sample solution (0.2 mg/mL) in only 6 min at room temperature. The VLP-functionalized impedance sensor is capable of label-free detection of target antibodies down to 55 pM concentration within 5 min. These results highlight the significant potentials of an integrated microsystem for rapid and controlled receptor-transducer interface creation and the nanoscale VLP-based sensors for fast, accurate, and decentralized pathogen detection.

HAVUZLU BALIK GEÇİDİ HİDROLİĞİNİN DENEYSEL İNCELENMESİ

In this study, the pool and weir fishway which is the most commonly used fishway in the world and in our country, was investigated experimentally. The experiments were conducted in an open channel system. The velocity area of the flow in five pools created by using weirs was measured by using aquistic doppler velocimeter. The orifices on the weirs were reduced in the ratio of ½ that of given in the literature for the grayling ( Thymallus thymallus ) or the brown trout ( Salmo trutta ) to pass. In the experiments for a discharge value of Q=6.2 L/s, the difference between the height of the water surface of downward and upward side of the first weir was found to be 2 cm and 1 cm for the others. For Q=12.2 L/s, these differences between the water surface heights were 5.5 cm for all weirs. The maximum velocities were obtained next to downward of the orifices. Moreover, far from the high velocity areas near the orifices, lower velocity areas in the pools that fishes could rest during the passes were determined. Keywords: Pool and weir fishway, aquistic doppler velocimeter, open channel, orifice

Optimization of Irrigation Scheduling Using Soil Water Balance and Genetic Algorithms

In arid and semi-arid countries, the use of irrigation is essential to ensure agricultural production. Irrigation water use is expected to increase in the near future due to several factors such as the growing demand of food and biofuel under a probable climate change scenario. For this reason, the improvement of irrigation water use efficiency has been one of the main drivers of the upgrading process of irrigation systems in countries like Spain, where irrigation water use is around 70 % of its total water use. Pressurized networks have replaced the obsolete open-channel distribution systems and on farm irrigation systems have been also upgraded incorporating more efficient water emitters like drippers or sprinklers. Although pressurized networks have significant energy requirements, increasing operational costs. In these circumstances farmers may be unable to afford such expense if their production is devoted to low-value crops. Thus, in this work, a new approach of sustainable management of pressurized irrigation networks has been developed using multiobjective genetic algorithms. The model establishes the optimal sectoring operation during the irrigation season that maximize farmer’s profit and minimize energy cost at the pumping station whilst satisfying water demand of crops at hydrant level taking into account the soil water balance at farm scale. This methodology has been applied to a real irrigation network in Southern Spain. The results show that it is possible to reduce energy cost and improve water use efficiency simultaneously by a comprehensive irrigation management leading, in the studied case, to energy cost savings close to 15 % without significant reduction of crop yield.

How to manage flood forecasting in a catchment with high flood risk - experiences from the Emscher

The Emscher area is a basin of 865 km2 , which includes nearly 2.3 million inhabitants. According to the average of 2.700 inhabitants per km2 nearly 60 % of the basin’s surface is sealed. 100 years of coal mining shaped the basin significantly. Due to that open channel system, the Emscher river shows a very quick reaction on precipitation. What does that mean for our flood forecasting? We have to record our data of the river gauges in an adequate time interval, that is usually 1 min. We have to import this recorded data from the gauges in our timeseries database every 5 minutes. In several other time intervals we’re getting our precipitation data, the radar data and the available numerical weather forecast from the German Weather Service. All this serves as input data for multiple model runs. The flood forecasting models perform continuous calculations every half an hour. All in all we’re offering an hydrological forecasting service for the operational branch of our organization so that they can handle the occurring problems. If necessary we’re performing this duty in a shift work system, so that we can offer a 24 hours service as long as needed.

Energy cost optimization in pressurized irrigation networks

The increasing demand and price for energy are affecting all economic sectors, including irrigated agriculture. This sector has undergone substantial transformations to improve water use efficiency by adapting its open-channel distribution systems to pressurized networks, which entail greater energy consumption and hence higher energy costs. Farmers are therefore demanding measures to reduce energy costs and ensure the profitability of their farms. In this paper, previous energy optimization models focusing on network sectoring (WEBSOM) and critical points control (WECPM) are improved by incorporating an electricity tariff module that considers different energy prices according to the hour of the day and the day of the year. The model permits determining the minimum energy cost affected by different operation conditions of the network. The methodology has been analyzed in an irrigation network located in southern Spain in which different operation scenarios were evaluated: operation with and without sectors and with and without critical points control. The results show that adopting measures to improve the operation of critical points in months of peak energy demand and operation by sectors in the others leads to a 13 % cost savings compared to the baseline scenario where only pressure heads at the pumping stations are optimized. The proposed model is a decision-making support system that integrates alternative irrigation network operation scenarios with the structure of the electricity tariff.

Calibrating pollutant dispersion in 1-D hydraulic models of river networks

The objective of this article is to investigate the major issues associated with the calibration of the pollutant dispersion in 1-D hydraulic models applied to river networks, especially large, complex, artificialized ones where ecological and socio-economical threats are important. Such issues are illustrated and discussed using the results of five fluorescent tracer experiments conducted in contrasted open-channel systems, ranging from a simple trapezoidal canal to a more complex river network. Experimental dispersion values were quantified using both the change of moment method and a simple fit-by-eye procedure for eight river reaches with homogeneous hydraulic conditions and an achieved tracer mixing and dispersive equilibrium. Since dispersion coefficient values depend on the assumed dispersion model, ideally they should be calibrated using the same model in which they are to be used, as was done in this study. We also derived concurrent longitudinal dispersion values using the velocity field measured by hydro-acoustic profilers (ADCP), which appears as a promising and cost-efficient technique for documenting dispersion in large river systems. It appears that the formulae for which the fit was mainly based on the cross-sectional aspect ratio are generally more appropriate for field data than those which are sensitive to the velocity to shear velocity ratio. The interpretation of complex dispersion and mixing processes, along with the selection of relevant dispersion coefficient predictors are key to minimizing errors in the numerical simulation of pollution dynamics in river networks.

A decentralized optimal LQ state observer based on an augmented Lagrangian approach

This paper is devoted to the design of a decentralized optimal batch LQ state observer for state estimation of large-scale interconnected systems, well suited for implementation on a sensor network. The here-proposed approach relies on both the use of an augmented Lagrangian formulation and a price-decomposition–coordination algorithm. The state estimation of an open-channel hydraulic system illustrates the effectiveness of this approach and is used to provide a comparison with alternative methods.

Site Investigation Of Road Drains For Rural Road On Batu Pahat Soft Clay (BPSC)

Road failures may be caused by many factors. In Batu Pahat district, open channel system is adopted and built on Batu Pahat Soft Soil and may be a crucial factor to probable damage of the rural roads structure. This study is focused on the drainage system for rural roads in Parit Raja, Batu Pahat. The type of damages is observed and the causes are identified. Recommendations on the best method are made to improve the effectiveness of current drainage system. Both site and laboratory geotechnical testing are carried out to analyze the causes of failure to the drainage system. Laboratory testing such as sieve analysis, moisture content, Atterberg limit, specific gravity and shear strength are conducted. While Mackintosh probes testing and vane shear test are conducted for site testing. From the analysis, four categories of drainage failure such as soil movement, edge drop, cracking and erosion due to the characteristics of soft clay that have low shear strength and high compatibility, have been determined. The propose methods to increase the effectiveness of the drainage system are to stabilize the soil using geotextiless, combination geotextiless and geocontainers, soil anchor and lime.

Infinite-Dimensional Predictive Control for Hyperbolic Systems

This paper presents a predictive control scheme, based on the receding horizon optimal control (RHOC) approach with zero terminal constraint, to guarantee the closed-loop stability of linear $2\times 2$ hyperbolic systems with boundary control. The extension of this control scheme to networks of such hyperbolic systems is also considered. The boundary control problem is first reformulated in the abstract form for which the optimal control with terminal constraint was well studied. These results are then used in the RHOC scheme to give a complete proof of stability of the closed-loop system. For the implementation, the calculus of variations is used to derive the adjoint state which is then discretized and solved together with the state to obtain the optimal control. The analysis is applied to open-channel hydraulic systems in cases of single pool and multipools in cascade. Finally, simulations are carried out to illustrate the effectiveness of the here-proposed approach.

Assessment of data-driven modeling strategies for water delivery canals

The aim of this paper is to develop models for experimental open-channel water delivery systems and assess the use of three data-driven modeling tools toward that end. Water delivery canals are nonlinear dynamical systems and thus should be modeled to meet given operational requirements while capturing all relevant dynamics, including transport delays. Typically, the derivation of first principle models for open-channel systems is based on the use of Saint–Venant equations for shallow water, which is a time-consuming task and demands for specific expertise. The present paper proposes and assesses the use of three data-driven modeling tools: artificial neural networks, composite local linear models and fuzzy systems. The canal from Hydraulics and Canal Control Nucleus (Evora University, Portugal) will be used as a benchmark: The models are identified using data collected from the experimental facility, and then their performances are assessed based on suitable validation criterion. The performance of all models is compared among each other and against the experimental data to show the effectiveness of such tools to capture all significant dynamics within the canal system and, therefore, provide accurate nonlinear models that can be used for simulation or control. The models are available upon request to the authors.

Potential Flow Solution for Open-Channel Flows and Weir-Crest Overflow

AbstractWeirs used for water discharge measurement in open-channel systems normally operate under free-flow conditions, for which the specific energy reaches a minimum at the weir crest. This type of transitional open-channel flow can be simulated using the ideal fluid flow theory. The traditional application of that theory requires the computation of the flow net over the weir. In this work, a potential flow model using a semi-inverse mapping is proposed in order to simulate potential flow over weirs. The model reduces the computation of the entire flow net to the determination of the streamline flow pattern only. The computations are conducted numerically using a simple finite-difference technique, in which conservation of energy, momentum, and the critical flow condition with curvilinear streamlines is considered. The model is used to display parameters of engineering interest at the point of minimum specific energy.

Discharge prediction using hydraulic characteristics of mean velocity equation

Discharge is an important factor in river design for water utilization, water control and hydraulic structures; therefore, an accurate estimation of the discharge is required. At present, a rating curve depicting the relationship between a stage and discharge is used to calculate the discharge from river systems. Although the rating curve has an advantage in that it can predict and use the discharge during the flood season in which the measurement is difficult, there is room for improvement as it does not reflect the hydraulic characteristics of rivers. Therefore, in this study, discharge was predicted using the convenient calculation method with empirical mediating variables of the Manning and Chezy equations which were proposed by the author’s previous research as a new methodology for estimating discharge in an open channel. This was proven, based on the data measured in a meandering open channel system in a lab at the Mississippi River in the US and at the Columbia Del Dique Canal, and an accuracy level at a coefficient of 0.8 was demonstrated. Thus, this method, which reflects the hydraulic characteristics and predicts the discharge in a simple manner, is expected to be convenient in practice.

Numerical simulation of heat and mass transport in water bodies

Presented is the numerical simulation of heat and mass transport in complex open channel systems using the mathematical models and numerical methods based on one- and two-dimensional (longitudinal-vertical) equations of shallow water (Saint Venant equations). The models take account of real morphometric and hydraulic characteristics of channels of the water system under consideration. Analyzed are the problems of adequacy of physical and mathematical models. Given are the examples of numerical computations of unsteady flows (hydrodynamic regime and transport of substances) in the open-channel and lake-river systems.