Hydraulic Parameters Of Flow Research Articles

Numerical Investigation of Hydraulic Parameters of Flow Passing through Multiple SMBF Flumes

Numerical Investigation of Hydraulic Parameters of Flow Passing through Multiple SMBF Flumes

Surge irrigation modeling and scenario analyses for the best furrow irrigation management practices

Furrow irrigation with surge flow is a management strategy to improve irrigation performance compared to furrow irrigation with continuous flow. Successful management of surge irrigation corresponds to accurate field practices that depend on different flow hydraulic parameters that make it complex in practice. However, because of this complexity, very few surge infiltration models have been developed. So far, no study has been done to evaluate infiltration equations subject to different surge irrigation modelling concepts under field surge irrigation scenarios. This study investigates two surge infiltration equations of Modified Kostiakov-Lewies (MKL) and Branch Function (BF) using WinSRFR that is the only modelling tool to simulate surge irrigation by using two surge infiltration modelling concepts of Blair-Smerdon (BS) and Izuno-Podmore (IP). Field data were collected on different combinations of two furrow lengths (70 m and 90 m; open-end furrows), two inflow rates (0.4 l s−1 and 0.6 l s−1), and two cycle ratios (0.5 and 0.33). Field measurements confirmed that switching from continuous to surge irrigation significantly improved irrigation performance. Evaluation of the surge infiltration modeling concepts showed that IP had higher accuracy in simulating irrigation performance compared to BS. The MKL(IP) and BF(IP) had the highest accuracy in the simulation of advance time, infiltrated water depth, and runoff. Further analyses showed that decreasing the cycle ratio from 0.5 to 0.33 improved simulation accuracy in advance time, runoff, and irrigation performance, but it reduced the accuracy of simulated infiltrated water depth. Increasing the inflow rate from 0.4 l s−1 to 0.6 l s−1 decreased the accuracy of irrigation performance. However, field observations were only under a limited number of furrow lengths and inflow rates that might not be the best management field practices to increase irrigation performance. Scenario analyses were done to simulate irrigation performance under a combination of possible irrigation managements. The optimal irrigation scenario consisted of adjusting the different inflow rate (0.5–1.2 l s−1), furrow length (100–300 m), cutoff time (360–600 min), and on-time (20–60 min). Results show that using cutoff 360 min and on-time 60 min led to reducing deep percolation and runoff and increasing the distribution uniformity. Based on the scenario analyses for the most efficient irrigation performance in terms of irrigation efficiencies and water losses (runoff and deep percolation), the best irrigation management could be attributed to the furrow length of 200 m that occurs for on-time of 60 min, with a cutoff time of 360 min, and an inflow rate of 0.7 l s−1 although Zreq = 50 mm is not fully irrigated over the whole furrow. Under this scenario, 35 % of the furrow is under deficit irrigation. Scenario analyses showed that we may propose a new surge irrigation management named as “wet-cycle surge irrigation” such that the first surge completes the whole furrow length, and then the subsequent surges will run on wet soil.

Analysis of hydraulic parameters in determining the occurrence of cavitation in the spillways of the Furnas, Luiz Carlos Barreto de Carvalho and Batalha hydroelectric power plants

Analysis of hydraulic parameters in determining the occurrence of cavitation in the spillways of the Furnas, Luiz Carlos Barreto de Carvalho and Batalha hydroelectric power plants

Response of flow hydraulic parameters to different rock fragment coverages and sizes under simulated rainfall

Rock fragments widely occur on slopes and play a vital role in flow hydraulics, which in turn greatly affects soil erosion. This study aimed to explore the effects of the rock fragment coverage and size on flow hydraulic parameters and determine the optimal flow hydraulic predictor of soil loss rate. A series of simulated rainfall experiments (intensity: 60 mm h-1) were conducted in a 2 × 1 × 0.3 m flume with a gradient of 15°. The rock fragment treatments included a combination of eight sizes (0.7, 1.1, 3.0, 5.5, 12.0, 18.8, 26.4, 36.0 cm) and four coverages (15, 30, 45, 60%). Bare land was used as a control. The results indicated that compared with bare land, rock fragments remaining on the soil surface decreased the flow velocity (V) by 1–51% but increased the flow depth by 8–315%. Laminar flow occurred in all experiments (Reynolds number < 500). Only the overland flow under rock fragment sizes ≤ 3 cm was subcritical flow. Resistance (f) exponentially increased with rock fragment coverage at each size, while grain resistance percentage (f'/f) exponentially decreased with rock fragment coverage. Rock fragment size impacted positively on f’/f, grain shear stress (τ'), stream power (ω), grain stream power (ω'), but negatively on f. τ’ and ω’ decreased with rock fragment coverage in exponential equations, and the parameters in the equations logarithmically increased with rock fragment size. The soil loss rate increased exponentially with V and τ’, and increased linearly with ω’. ω’ was the optimal hydraulic parameter for soil loss prediction (R2 = 0.88; NSE = 0.80). Our findings can help to deepen the understanding of the mechanisms of the soil erosion process and provide insights into establishing soil loss prediction models on stony slopes.

Determination of the pressure flow parameters of a structured suspension

The subject of the research is the methods of calculating the parameters and flow regimes of structured suspensions, which have significant potential for substantial reduction in energy consumption and specific water consumption of all hydromechanization technologies used in mining enterprises. The main topic of the research is the stability of the suspension structure and uniform distribution of particles of its solid phase throughout the volume during pressure flow through the pipeline. The aim of the work is to establish dependencies on the relative radius that defines the flow area where the suspension structure is not destroyed, not only on the rheological characteristics of the suspension and hydraulic flow parameters but also on the gravitational and repulsive forces between the particles of the solid phase of the suspension, which have an ion-electrostatic and Van der Waals nature. It is established that forces having ion-electrostatic and Van der Waals nature lead to a decrease in the maximum value of the relative radius, at which the suspension structure is still preserved during its flow in the pipeline, since the addition that takes into account their influence is always positive and subtracted from the addition that takes into account the relationship between the initial tangential stress and the hydraulic frictional stress on the inner surface of the pipe. The range of existence of the addition that takes into account the influence of forces having ion-electrostatic and Van der Waals nature and the range of variation of its values аt different values of the parameter of the energy interaction of particles of the solid phase of the structured suspension are investigated. It is established that the dependence of this addition on the distance between particles of the solid phase of the suspension is maximum. The magnitude and coordinates of the maximum depend on the parameter of the energy interaction of the solid phase particles. It is established that with an increase in the value of the parameter of the energy particles interaction of the suspension solid phase, the maximum value of the addition decreases, and the coordinate of this maximum increases. Keywords: structured suspension, radius of undeformed flow core, ion-electrostatic forces, pressure flow, pipeline.

Calculation of bank deformation in the confluence of two streams

In the article, on the basis of the comfort reflection method, the bank washout that occurs in the joining area of open channels and its effect on the flow pattern is studied. It is shown that the flow hydraulic parameters depend on the angle of joining of the channels.

Dissolved oxygen determination in sewers using flow hydraulic parameters as part of a physical-biological simulation model

Abstract This paper aims to develop a model for calculating the hydraulic and water quality parameters of wastewater within sewers. Information from the wastewater collection network and the transmission line in Birjand were used to verify the model performance. The parameters used for modelling quality changes include the yield constant for biomass (YH), the maximum specific growth rate (μH), the saturation constant for dissolved oxygen (KOG) and the saturation constant for readily biodegradable substrate within a biofilm (KSF), as well as the Gauckler–Manning–Strickler coefficient (n). They were selected from references and were verified at the calibration stage comparing measurements with the modelling values. Inputs of the created model are the average concentrations of dissolved oxygen and chemical oxygen demand of the incoming wastewater, the flow rate of wastewater at the exit point of the network, physical characteristics of the pipes and the height of drops within the sewer network. The amount of dissolved oxygen at different positions of the sewer network was calculated. The acceptable calculated sum of squares of errors and the correlation coefficient (R2) of the calibrated model for dissolved oxygen were 1.6872 and 0.77, respectively.

Flow hydraulics in an ephemeral gully system under different slope gradients, rainfall intensities and inflow conditions

Overland flow in an ephemeral gully (EG) system includes the EG channel, rill and interrill sheet flows, which comprise an interconnected drainage network. There are abundant researches on the hydraulics of rill flow and interrill sheet flow, as well as their relationships with soil detachment rates and sediment loads. Few studies have quantified the flow hydraulics of EG system which is highly related to the EG erosion and the development of better EG management strategies. Thus, two erosive rainfall intensities (50 and 100 mm h−1) and two slope gradients (15° and 20°) under different upslope and lateral inflow boundary conditions were employed to study the flow hydraulics of an EG system using simulated rainfall and inflow experiments. The results showed that flow velocity, shear stress, stream power and cross-sectional energy in the EG channel generally increased from the top to bottom of the slope with different trends and fluctuations under various inflow conditions. The flow hydraulic parameters of EG channel, rill, and interrill sheet flows all increased as rainfall intensity and slope increased. Flow regimes in the EG system were divided based upon the Reynolds number and Froude number. EG channel flow was classified as transitional to turbulent flow, rill flow was transitional, while sheet flows on interrill areas was laminar. From sheet flow to rill flow and EG channel flow, the flow regime gradually shifted from laminar and subcritical flow to turbulent and supercritical flow. The flow force, power and energy correspondingly increase as flow regime changed toward turbulent and supercritical. Good relationships between sediment load and flow hydraulic parameters were observed and flow shear stress was found to be best correlated with soil erosion of the EG system (R2 = 0.92). This study quantitively mapped the flow hydraulics in the EG system and correlated these with erosion features, contributing to the development of process-based EG prediction models and better EG management strategies.

The effectiveness of selected vegetation communities in regulating runoff and soil loss from regraded gully banks in the Mollisol region of Northeast China

AbstractThe steep slopes of actively developed gullies are extremely sensitive to erosion in the Mollisol region of Northeast China; however, decision making on the optimal configuration for gully bank protection is under discussion. Here, five vegetation communities were established on regraded gully banks with bare slopes as the control to identify their controlling effects on flow hydraulics and soil erosion through in situ scouring experiments. A hydraulic flume experiment was conducted to clarify the ability of roots to reduce erosion. For vegetated slopes, flow velocity, stream power, and unit stream power decreased by 42–67%, 0–18%, and 44–68%, respectively, while flow depth, shear stress, the Darcy–Weisbach friction coefficient, and Manning coefficient increased by 55–150%, 69–156%, 5–22‐times and 2–5‐times, respectively. Changes in the seven flow hydraulic parameters were significantly influenced by vegetation coverage, aboveground biomass, root mass density and litter biomass (p &lt; .05). Consequently, the five vegetation communities experienced decreased runoff and soil loss by 19–30% and 78–97%, respectively. Vegetation with tap‐roots and rich roots of 1.0–2.0 mm in diameter was more effective in controlling gully bank erosion. Thus, the vegetation community consisting of Dactylis glomerata, Festuca arundinacea, Uraria crinita and Medicago sativa (25:25:25:25) is perfectly acceptable for gully bank protection in the Mollisol region of Northeast China. The results provide a scientific reference for selecting optimal vegetation configuration for gully bank rehabilitation.

Nappe Flow Characteristics over Stepped Spill Ways.(Dept.C)

Stepped spillways are structurally stable, resistance to water loads, and efficient. energy dissipators, but there are no clear design rules for such structures to date. In the present study, the flow characteristics over stepped spillways were investigated for three different step configurations and for different flow parameters, using physical models. Nappe flow regime over the stepped spillways was studied. A definite equation representing the onset of the nappe flow regime was developed using the experimental observations and experimental data of other researchers. In addition, the energy dissipation for the napp e flow regime was extensively investigated for different flow hydraulic parameters. The experimental observations were compared to empirical and analytical formulas of other researches. Finally, using the experimental data in addition to that of other researchers, analytical equation: have been developed and it can be used for computation purposes of the energy dissipation of nappe flow regime over stepped spillways.

Hydraulic parameters in the area of the main dam intake structure of the river

The article presents the study results of changes in flow hydraulic parameters and morphometric elements of the river in the area of the main dam intake structure. A model for studying the direction of flow and other parameters of the flow in the area of the main structure for obtaining water from the Amudarya without a dam has been developed. A functional graph of the depth dependence of the expenditure on the study object was obtained. Graphs of the functional dependence of the diurnal cross-section of the riverbed on the flow depth and the variation of the flow velocity depending on the flow depth were constructed. The direction and distribution of the flow in the area of the main dam intake structure were studied.

A Novel Comprehensive Evaluation Method for Estimating the Bank Profile Shape and Dimensions of Stable Channels Using the Maximum Entropy Principle.

This paper presents an extensive and practical study of the estimation of stable channel bank shape and dimensions using the maximum entropy principle. The transverse slope () distribution of threshold channel bank cross-sections satisfies the properties of the probability space. The entropy of is subject to two constraint conditions, and the principle of maximum entropy must be applied to find the least biased probability distribution. Accordingly, the Lagrange multiplier (λ) as a critical parameter in the entropy equation is calculated numerically based on the maximum entropy principle. The main goal of the present paper is the investigation of the hydraulic parameters influence governing the mean transverse slope () value comprehensively using a Gene Expression Programming (GEP) by knowing the initial information (discharge (Q) and mean sediment size (d50)) related to the intended problem. An explicit and simple equation of the of banks and the geometric and hydraulic parameters of flow is introduced based on the GEP in combination with the previous shape profile equation related to previous researchers. Therefore, a reliable numerical hybrid model is designed, namely Entropy-based Design Model of Threshold Channels (EDMTC) based on entropy theory combined with the evolutionary algorithm of the GEP model, for estimating the bank profile shape and also dimensions of threshold channels. A wide range of laboratory and field data are utilized to verify the proposed EDMTC. The results demonstrate that the used Shannon entropy model is accurate with a lower average value of Mean Absolute Relative Error (MARE) equal to 0.317 than a previous model proposed by Cao and Knight (1997) (MARE = 0.98) in estimating the bank profile shape of threshold channels based on entropy for the first time. Furthermore, the EDMTC proposed in this paper has acceptable accuracy in predicting the shape profile and consequently, the dimensions of threshold channel banks with a wide range of laboratory and field data when only the channel hydraulic characteristics (e.g., Q and d50) are known. Thus, EDMTC can be used in threshold channel design and implementation applications in cases when the channel characteristics are unknown. Furthermore, the uncertainty analysis of the EDMTC supports the model’s high reliability with a Width of Uncertainty Bound (WUB) of ±0.03 and standard deviation () of 0.24.

A model ensemble generator to explore structural uncertainty in karst systems with unmapped conduits

Karst aquifers are characterized by high-conductivity conduits embedded in a low-conductivity fractured matrix, resulting in extreme heterogeneity and variable groundwater flow behavior. The conduit network controls groundwater flow, but is often unmapped, making it difficult to apply numerical models to predict system behavior. This paper presents a multi-model ensemble method to represent structural and conceptual uncertainty inherent in simulation of systems with limited spatial information, and to guide data collection. The study tests the new method by applying it to a well-mapped, geologically complex long-term study site: the Gottesacker alpine karst system (Austria/Germany). The ensemble generation process, linking existing tools, consists of three steps: creating 3D geologic models using GemPy (a Python package), generating multiple conduit networks constrained by the geology using the Stochastic Karst Simulator (a MATLAB script), and, finally, running multiple flow simulations through each network using the Storm Water Management Model (C-based software) to reject nonbehavioral models based on the fit of the simulated spring discharge to the observed discharge. This approach captures a diversity of plausible system configurations and behaviors using minimal initial data. The ensemble can then be used to explore the importance of hydraulic flow parameters, and to guide additional data collection. For the ensemble generated in this study, the network structure was more determinant of flow behavior than the hydraulic parameters, but multiple different structures yielded similar fits to the observed flow behavior. This suggests that while modeling multiple network structures is important, additional types of data are needed to discriminate between networks.

Morphometric elements of the channel and hydraulic flow parameters in the zone of the river backwater

The article is devoted to the analysis of the dynamics of the morphometry of the river bed and the hydraulic parameters of the flow under conditions of flow regulation. For the analysis of the dynamics of the bed morphometry and hydraulic elements of the flow, the Nietbaitas hydro-array located in the zone of the sub-flow of the lower reaches of the Amudarya river in Uzbekistan was selected. As a result of the analysis of data from long-term field studies and hydrometric measurements at the Nietbaitas hydrostorm of the Amudarya river, functional relationships were established between the morphometric elements of the channel and the hydraulic parameters of the flow. The dynamics of the Chezy coefficient, hydraulic resistance, and the roughness coefficient of the channel in conjunction with the hydrodynamic characteristic of the flow are established. Adapted formulas are recommended for determining the calculated values of the Chezi coefficients, roughness, and average flow velocity, taking into account the decelerating effect of the banks of the Amudarya river bed

Variations of infiltration capacity with flow hydraulic parameters in permeable stormwater channels

ABSTRACT Permeable channels are commonly adopted for urban stormwater management as an infiltration device. However, in the design of such channels, the effects of flow hydraulic parameters (i.e. water level, channel cross section and flow velocity) on the infiltration capacity of a permeable channel have usually been neglected. In this study, the variations of infiltration capacity with flow hydraulic parameters in permeable channels were investigated in various cases of static and dynamic flows. For the static phase, physical channels models were fabricated in the laboratory and the investigations were performed under ponding condition, while a grassed channel model was constructed for the dynamic phase. The results show that the water level and channel side slope affected the infiltration capacity more than the base width. The results also show that increasing the hydraulic residence time significantly affected the infiltration rate. Observed infiltration rates were used to develop a predictive infiltration model that considers the flow hydraulic parameters by adding them to the Kostiakov model. The use of this infiltration model promises better prediction accuracy of the infiltration rate in permeable channels.

Different Self-Oscillation Modes in Flows with a Ventilated Cavity and Their Possible Use in Forming Periodic Pulsed Jets

The problem of the generation of cavitation self-oscillations in a liquid flow in a pipe with two resistances is considered. The first resistance is a cavitator, behind which there is an artificial ventilated cavity, where the mean pressure is greater than the atmospheric pressure, while the liquid and gas outflow into the atmosphere takes place through the second resistance. Investigations show that the self-oscillation frequencies are chiefly determined by the cavity properties and the conditions of the outflow into the atmosphere. The generation of different self-oscillation modes is directly associated with the number of waves formed along the cavity length. It is shown that the pressure pipeline properties and the cavity volume have an effect on the cavitation self-oscillation mode (up to four frequency modes can be observable at the same geometry and hydraulic flow parameters). The question arises of whether the self-oscillations can be used for generating pulsed jets at the outlet. It seems that it is the first mode regime that is most suitable for producing the pulsed jets, since in this case the pressure fluctuations in the cavity are maximum. Using the exponential Voitsekhovskii nozzle the regimes, in which an intermittent jet flow of the liquid is realized at the outlet, are experimentally obtained.

The influences of mass failure on the erosion and hydraulic processes of gully headcuts based on an in situ scouring experiment in Dry-hot valley of China

Gully headcut retreat (GHR) is an important processes in gully development, and previous studies have tried to predict GHR rates based on flow hydraulic parameters during runoff scouring, but other dynamics such as gravity also affect GHR processes in addition to flow hydraulics. The aim of this study is to examine the influences of mass failures due to gravity on the erosion and hydraulics processes of gully headcuts during runoff scouring. A flow scouring experiment including 11 tests with two discharges (i.e., 7 tests with 83.3 l min−1 and 4 tests with 166.7 l min−1) was conducted on 5 in situ gully head plots with similar initial topographies. Totally 36 mass failure events were observed of all the 5 gully heads during the experiment, and 63.9% of the events were occurred during the first 10 min of the tests after drying-rewetting cycles. The tests were classified into two series according to whether the mass failure occurred during the scouring. The tests with mass failures (Series I) contributed 81.7% of the total soil loss of GHR, and the average GHR rates by mass (GHRm) was about 5 times higher than that of the tests without mass failures (Series II). The mass failure clearly influenced the flow resistances on gully beds by increasing the surfaces roughness and the sediment load to gully beds, and the average Darcy–Weisbach friction factor (f) and Manning coefficient (n) of Series I were clearly higher than those of Series II. Compared to the previous studies without significant soil collapse from gully heads, the logarithmic growth relationship between GHRm and the energy consumption (ΔEt) was quite weak in this study, but the R2 between GHRm and ΔEt increased for longer time scales. The results indicated that for individual runoff events, GHR rates could not be predicted by flow hydraulics alone because mass failures due to gravity made great contribution, but on longer time scales, the influence of soil collapse is reduced, and flow hydraulics become the key factor impacting GHR processes.

Heat transfer of a bubbly flow in a vertical rod bundle 3X3

This work aims at creating a reserve for increasing the efficiency of nuclear power plants. One of the main ways to intensify heat transfer in fuel assemblies is to increase the permissible mass concentration of the vapour phase. It is known that the introduction of a gas phase into a fluid flow leads to a modification of the flow structure and can significantly change the key thermal and hydraulic flow parameters, for example, the heat transfer coefficient. In this paper, we present the results of an experimental study of an ascending bubble flow in a vertical rods bundle 3X3. The working liquid was distilled water. The experiment was carried out at Reynolds numbers from 4000 to 11000 and gas flow rate ratios from 3 to 10%. As a result of the experiment, the heat transfer coefficients from the central rod heated by the electric current to the flow have been determined. It is shown that gas bubbles have the greatest effect on heat exchange at low Reynolds numbers and at a maximum distance from the spacer grid.

Numerical simulation of the hydraulic performance of triangular and trapezoidal gabion weirs in free flow condition

During the recent years, gabion weirs have attracted the attention of many researchers due to their compatibility with the environment, positive effects on river's water quality and simple design and implementation. In this research, the hydraulic parameters of flow around the triangular and broad-crested gabion weirs with various side slopes were numerically investigated. The numerical results were validated using the data obtained from laboratory experiments. Overall, a number of 256 different models were studied numerically. Results indicated that decreasing the average diameter of particles may result in the reduction of the discharge coefficient (Cd), through flow discharge and the energy dissipation of flow over the models up to 27%, 34%, and 8% respectively. Also, it was concluded that the upstream slope of triangular weirs and downstream slope of broad-crested gabion weirs have more significant impact on the performance of gabion weirs. Finally, mathematical relationships are correlated using Nonlinear Multivariate regression analysis in order to estimate the discharge coefficient and through flow discharge of these structures.

Comparison of the MODFLOW modules for the simulation of the river type boundary condition

The aim of this article is the comparison of input options of river boundary condition of MODFLOW - three-dimensional numerical simulation model of groundwater flow. The water level in stream flowing through territory of hydrogeological layer can be computed via three built-in modules: River, Stream and Streamflow-Routing. In this study the code MODFLOW is used to simulate idealized aquifer and stream. The differences between computed groundwater table showed to be minimal, thus in case of modules Stream and Streamflow- Routing they are equally usable as using module River with external one or two-dimensional simulation of surface water flow, which is more time-consuming process. However, this applies only to idealized, simplified conditions of the modeled environment. For more complex simulation of flow in streams with irregular structure of the streambed is necessary to use either an external simulation or use the Streamflow-Routing module, which includes the possibility to enter more complex hydraulic flow parameters in the model.