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Seismic stress may cause changes in the hydraulic characteristics of aquifers and corresponding changes in the movement state of the groundwater flow. In this study, based on the theoretical relationship between the tidal response of the well water level and an aquifer's hydraulic characteristics, the hydraulic parameters of an observed aquifer in the Chongqing area are estimated through the tidal response of the well water level, and the influence of the Wenchuan earthquake on the hydraulic characteristics of the aquifer and the movement of the groundwater is discussed. The results showed that the groundwater near well DZ was mainly controlled by horizontal flow accompanied by extremely weak vertical leakage, and the hydraulic conductivity of the target aquifer calculated using the tidal radial flow model was basically consistent with the results of previous pumping tests. Vertical and horizontal flow coexist in the aquifer system near wells BB and BN, and the specific leakage can be obtained using the mixed aquifer model. The intense tectonic static stress caused by the Wenchuan earthquake resulted in obvious tensile deformation of the aquifers near these three wells, which became the main reason for the changes in the well water level and the enhanced vertical leakage. In addition, the rise in the water level in well BN may have been related to its artesian characteristics and hydrogeological conditions. This article deepens our understanding of the influence of seismic stress loading on groundwater flow in regional aquifers. [ABSTRACT FROM AUTHOR]

Drought and salt stress are important abiotic stressors that adversely affect the growth, resistance and survival of plants. Haloxylon ammodendron is a strong halophyte, and its hydraulic characteristics and carbon metabolism response to drought and salt stress under natural conditions have not been widely studied. With H. ammodendron as the research object, three sample plots with different water and salt contents (high water and high salt, medium salt in reclaimed water, low water and low salt) were selected to determine their water physiology, photosynthetic physiology, carbon physiology and growth status under different water and salt conditions. Studies have shown that drought and salinity affect the hydraulic properties of H. ammodendron , reducing the water content and water potential of assimilation branches and secondary branches and increasing the hydraulic conductivity per unit cross-sectional area of biennial shoots. Affected by drought, the content of non-structural carbohydrates (NSCs) in assimilation branches and secondary branches was significantly reduced, and the NSC content of assimilating branches was significantly higher than that in secondary branches. The transportation of NSCs to the secondary branches caused obstacles, and more accumulated in the assimilating branches. In addition, drought reduced H. ammodendron photosynthesis and carbon assimilation and limited carbon uptake, resulting in slower growth. Under the influence of drought and salinity, the anisohydric properties of H. ammodendron weakened its stomatal regulation ability and made it susceptible to water transport obstacles, but the degree of carbon limitation was relatively small. [ABSTRACT FROM AUTHOR]

In the present study, the discharge capacity and the hydrodynamic behavior of A-type piano key weirs with simple crests and non-simple crests with zigzag indentations in various geometries, including triangular, rectangular, trapezoidal, and semi-circular zigzag crests, were investigated. First, using laboratory data and results of numerical simulation with Flow-3D software, the discharge capacity and the discharge coefficient of the weirs were determined and discussed. Then flow configuration over the weirs was studied in different submersion conditions. For this purpose, the formations of the streamlines passing over the weirs were extracted from the numerical results and were analyzed after matching with the laboratory observations. Furthermore, the energy dissipations of the weirs were calculated using the numerical results, and the effect of the geometry of the crests on the energy loss of the weirs was investigated. The results demonstrate that in relative water heads less than 0.5, the zigzag indentations of the lateral crests cause substantial increases in the discharge capacity and the energy dissipation of PKWs, though in higher relative water heads the geometry of the crest has no significant effect on the hydraulic behavior of weirs. Among all modified weirs, the PKW with semi-circular indentations has the best performance in terms of both discharge capacity and energy dissipation. For instance, in a relative water load of 0.07 the discharge capacity of this weir is more than twice that of the simple weir. [ABSTRACT FROM AUTHOR]

The fish pump is an important piece of power equipment for aquaculture, especially for deep-sea engineering vessels and cage culture. Fish pump research focuses on reducing fish body damage, improving survival rates, and increasing fish lifting efficiency. The research object in this paper is a new type of vacuum fish pump, with the aim of improving the hydraulic performance of the vacuum fish pump and reducing the damage to the fish body. The dependent variables include the dynamic change process of the flow state and flow field under diachronic conditions, the fluid simulation analysis of the vacuum pump body and the flow channel structure, the inlet flow rate of the fish pump, the negative pressure of the pipeline, and the impact force of the water flow on the inner wall of the tank. The independent variables include the operating conditions of the pump body and the fish pump. The Latin hypercube sampling method is used to extract 167 sets of calculation models for the independent variables, and multi-objective optimization is performed based on the NSGA-II algorithm for the hydrodynamic performance of the fish pump. On the basis of ensuring the fish body damage rate, the structural parameters of the vacuum fish pump with the optimal hydrodynamic performance under 167 sets of parameter values were obtained. The optimized parameters were then entered into the solver again, and the results showed that, in the optimal structural parameters under certain conditions, the direction of the incident water flow in the vacuum fish pump tank is close to the upper end of the tank body, which will reduce the speed of the fish-water mixed flow when entering the tank, thereby reducing the collision damage to the fish body. Currently, the water flow velocity at the water inlet is about 2.5 m/s, and the negative pressure value distribution gradient between the tank body and the water inlet pipeline is quite consistent, which can achieve good fish suction and fish lifting effects.

With the development of hydraulic structures, rivers are becoming fragmented, and their connectivity is greatly affected. Important migratory routes through which fish complete their life processes are hindered. In severe cases, it may lead to the extinction of fish species. As facilities commonly used to assist fish upstreaming, fishways are significant for environmental remediation and have received attention from different scholars. This article proposed a new type of fishway, inspired by Tesla valves with obstructing reverse flow characteristics and classic fishway structures. Due to its characteristic of introducing a water-blocking island structure, it was denominated as an island-style fishway. This work studied an island fishway through a combination of physical models and numerical simulations. The results show that this fishway could achieve various flow patterns suitable for fish migration, and the flow rate control was stable. This study also explored the impact of island spacing arrangement on the turbulent structure of the pool chamber. It was found that when the island distance is set at 1.5d, indicators such as flow velocity and turbulent kinetic energy could achieve significant control effects. However, inappropriate d values might cause adverse effects. This research could provide reference ideas for the design of new fishways.

Highlights: To study the hydraulic characteristics of natural continuous curved river flows; To study the influence of the hydraulic characteristics of natural continuous curved river flows on fish habitats; To evaluate the impact of channel regulation on the construction of ecological waterways. Increasing international attention is being focused on the construction of ecological waterways. Ecological waterways are not only able to successfully sustain the navigational functions for ships, but also provide a stable long-term environment in which fish can survive. In nature, meandering rivers are the most common form. Compared with straight rivers, their flow conditions are complex and not conducive to ship navigation and fish survival. There has been less research conducted on the construction of ecological waterways in naturally curving rivers. Therefore, in this paper, a naturally continuous curved river was used as a research object, and numerical simulation was employed to study the hydraulic characteristics of the river and the survival environment by fish by introducing the Shannon diversity index. It was concluded that a naturally continuous curved river cannot meet the navigational requirements and does not provide a stable survival environment for fish. After proposing a targeted channel restoration plan, the hydraulic characteristics of the flow were significantly improved, and the flow velocity Shannon diversity index was reduced. The restored channel met the navigational requirements of vessels, and provided a more stable environment for fish. In the construction of the continuous bend river ecological corridor, the location of the continuous bend stream connection was used as a key restoration area. This paper provides ideas and basic research for the sustainable development of ecological river channels and the construction of continuous curved river channels. [ABSTRACT FROM AUTHOR]

The water inlet channel is an essential component of the thermal power plant's circulating water system. It primarily arranges the water flow in the channel so that it is introduced into the pump room smoothly, steadily, and uniformly. Significantly, the operation state of the circulating water pump is impacted by the flow condition of the water inlet channel. The coal-fired generating set's water input channel was chosen as the research object in this work, and the Computational Fluid Dynamics (CFD) Method was used to examine hydraulic issues impacting anomalous vibration of circulating pumps. Nine optimization options were also suggested, and the effects of the various plans on the water inlet channel's flow state were examined—the simulation's outcomes. The simulation's findings indicate that the arc deflector can enhance the water entry channel's flow pattern. The wall-attached bias flow of the suction chamber vanished, and the constant flow state is present around the pump's bellmouth. The thermal power unit's circulating water pump's vibration was eliminated, and the circulating pump's operating efficiency increased due to the curved deflector's rectification procedures being implemented in the forebay. The study's findings can guide the hydraulic performance optimization of channels for water inlets with similar sideways or high slopes. [ABSTRACT FROM AUTHOR]

The hydraulic characteristics of the flow are measured using tools such as flumes, in the design and evaluation of furrow irrigation systems. Proper use of these tools, such as their immersion while working, is one of the important executive points in this field; in this study, trapezoidal flumes are used to measure the intensity of input and output flow in furrow irrigation. The proper method of installing these flumes was investigated in this article. For this purpose, during 60 irrigation operations, the results showed that in order to create free flow conditions in these flumes, and not to affect the downstream and upstream current, as well as increasing the accuracy of measurements, in addition to installing flumes in all directions, trapezoidal flume should be installed at a height of at least about 4 cm above the furrow bed; according to the irrigation operations, the percentage of immersion in the installation of the flume at a height of 4 cm from the furrow bed was observed as standard (less than 70% immersion) in order to reduce the percentage of flow measurement error in different depths of water entering the flume. The results also showed that for ensuring free flow in trapezoidal flumes, the flume should be installed at a height of 4 cm or more above the furrow bed, provided the input ridges are strengthened and the end flume is measured to measure the inflow to the furrow. The output current of the furrow should be installed in the floor of the furrow along the bed to prevent the passage of current, provided that after the outflow flume, the furrow bed should be deeper in terms of free flow. Observance of the points and results obtained in this study in furrow irrigation systems prevents errors in flow measurement and consequently increases the accuracy in the design and evaluation of furrow irrigation systems. [ABSTRACT FROM AUTHOR]

Pump as turbine (PAT) is a factual alternative for electricity generation in rural and remote areas where insufficient or inconsistent water flows pose a threat to local energy demand satisfaction. Recent studies on PAT hydrodynamics have shown that its continuous operations lead to a progressive deterioration of inner surface smoothness, serving the source of near-wall turbulence build-up, which itself depends on the level of roughness. The associated boundary layer flow incites significant friction losses that eventually deteriorate the performance. In order to study the influence of wall roughness on PAT hydraulic performance under different working conditions, CFD simulation of the water flow through an axial-flow PAT has been performed with a RNG k-ε turbulence model. Study results have shown that wall roughness gradually decreases PAT's head, efficiency, and shaft power. Nevertheless, the least wall roughness effect on PAT hydraulic performance was experienced under best efficiency point conditions. Wall roughness increase resulted in the decrease of axial velocity distribution uniformity and the increase of velocity-weighted average swirl angle. This led to a disorderly distribution of streamlines and backflow zones formation at the conduit outlet. Furthermore, the wall roughness impact on energy losses is due to the static pressure drop on the blade pressure surface and the increase of turbulent kinetic energy near the blade. Further studies on the roughness influence over wider range of PAT operating conditions are recommended, as they will lead to quicker equipment refurbishment. [ABSTRACT FROM AUTHOR]

Based on the Reynolds time mean N-S equation and standard k-ε turbulence model and using Computational Fluid Dynamics technology, this study aims to integrate the brake pump to carry out numerical simulation. Through the adoption of different arrangements of impending height and spacing, the hydraulic characteristics of the full tubular pump unit are analyzed. The two-dimensional streamline, velocity and pressure distribution, and three-dimensional streamline, axial velocity and vorticity distribution of the front pool of each scheme are displayed. The results show that the recommended pump installation height is 0.8 Dd, the maximum limit value of the pump station design specification; in the dual-pump mode, the recommended pump spacing is 2.00 Ds. [ABSTRACT FROM AUTHOR]

The leaching of material from concrete fracture surfaces has an impact on the structural concrete in service, but the number of studies that consider the effect of the coupling of the leaching, fracture geometry and hydraulic processes on concrete fractures is insufficient. In this study, a series of experiments was conducted, and a leaching model proposed, to investigate the mechanism of leaching behavior on the geometric and hydraulic characteristics of concrete fractures. Following the leaching experiment, the evolution of fracture geometric characteristics was observed by a three-dimensional (3D) laser scanning technique, finding that the fracture produces residual leached depth and local uneven leaching, which results in a decrease in roughness. The hydraulic characteristics were then investigated by permeability tests, and it was found that the fracture hydraulic aperture and permeability increase monotonically with leaching time. A simulation of fluid flow in a numerical fracture revealed the effect of residual leached depth and a decrease in roughness on the hydraulic characteristics. Finally, based on the analysis of the chemical composition of the leaching solution, a leaching model of concrete rough fracture surface is proposed and the mechanism of leaching behavior is discussed. These new findings are useful for the understanding of the development of leaching, local to concrete fracture surfaces. [ABSTRACT FROM AUTHOR]

The experimental simulation between the composite hydraulic structure and the found obstacles in the downstream region is a challenging process due to the energy losses and kinematic dissipation. The current work focuses on a comparative analysis of free flow conditions that exist without obstacles and submerged flow conditions that occur due to obstacles. It indicates the evaluation of hydraulic variables and geometrical variables of composite hydraulic structure for both flow conditions. In addition, it includes an investigation of the interaction among these variables. The hydraulic variables include actual discharge, flow velocity, flow cross-sectional area that crosses the gate, downstream water depth, discharge coefficient, Reynolds number and, Froude number, while the vertical distance between the weir and gate represents the geometry variable. The interference between the weir discharge and gate discharge plays a significant role in the result fluctuation and variation for both flow conditions, while the form and size of the obstacles only have a major effect on the submerged flow. For both flow conditions, the water depth is investigated; there would be a drastic increase in water depth by using obstacles in the downstream area as compared with not using the obstacles. This study adopts different obstacles in shape and size, therefore, the variation of maximum and minimum water levels related to the location will occur. [ABSTRACT FROM AUTHOR]

The cemented soils by trench cutting re-mixing deep (TRD) wall or trench cutting assembled diaphragm (TAD) wall are a mixture of various soils. The physical and mechanical properties of these cement-stabilized soils are thus not only affected by construction technologies but also significantly controlled by cement content and soil texture. Three typical soils, including clay soil, silty soil, and fine sand, were used to prepare samples of cement-stabilized soils with different combinations of cement content and soil texture. Then, the workability (including fluidity, cohesion, and water retention), strength, hydraulic, and microstructure characteristics of different cement-stabilized soils were investigated by depth compression, permeability, and microstructural tests. Results indicate that there should be a higher water-cement ratio for clay soil while a low value for fine sand to achieve the required compactness. The unconfined compressive strength of cement-stabilized soils increased linearly with cement content, while their permeability had an approximate power relationship with cement content. The permeability magnitude of cement-stabilized composite soils was greatly affected by the proportion of the soil with high permeability. The clay soil could partly improve the pore structure of cement-stabilized composite soils and reduce permeability due to fine particles’ high activity, which was further confirmed by the microstructural analysis. The relationship between unconfined compressive strength and permeability coefficient was approximately consistent with a power function. The unconfined compressive strength of cement-stabilized soils decreased linearly with porosity, and the logarithm to base 10 of permeability coefficients of cement-stabilized soils increased with porosity. [ABSTRACT FROM AUTHOR]

• A dedicated hydraulic test facility for fuel rod irradiation device was designed and built. • The throttling components that match the design flow rate were selected through hydraulic characteristic testing. • Numerical simulation is an effective method to optimize the throttling elements of irradiation devices. In order to explore the rationality of the design of the fuel rod irradiation test facility, this paper presents a comprehensive study based on theoretical analysis, hydraulic characteristics test, and numerical simulation. First, the design requirements of the fuel rod irradiation test device were analyzed, and the fuel rod hydraulic characteristics test device was designed based on the resistance similarity principle. Next, the orifice plate and throttling components that match the design flow rate were selected through hydraulic characteristic testing to verify the flow adjustment range of the device. Then, the flow field characteristics of the throttling component are studied through numerical simulation, and the distribution of parameters such as speed, pressure, and temperature are obtained. The results of these methods proved the rationality of the design of the fuel rod irradiation test device as well as the throttling component. [ABSTRACT FROM AUTHOR]

Diaphragm fishways are often used in fishway engineering construction. Although there are an increasing number of new types of fishways, other types of diaphragm fishways can be derived from the combination or evolution of the following three basic types of fishways: vertical slot, overflow weir and orifice. To compare the hydraulic characteristics of different foundation types of fishways, the operations of vertical slot fishways, overflow weir fishways and orifice fishways are calculated by numerical simulation, and we comprehensively compare the flow field characteristics and application scenarios of various types of fishways from the two dimensions of hydraulic characteristics and application characteristics. This paper analyses the hydraulic characteristics of the flow field, such as velocity distribution and turbulent kinetic energy, and analyses the application characteristics of the fishway from the aspects of applicable flow, favourite swimming speed range, explosive swimming speed, fish passing position, and the matching characteristics of typical target fish. It is concluded that the vertical slot fishway can be widely applied to different target fish species due to its own advantages, such as less impact from environmental conditions. The characteristics of the overflow weir fishway and orifice fishway need to be analysed in combination with the hydraulic characteristics of the fishway, the swimming ability of the target fish species and the natural environmental conditions.

【Background】 The flow velocity in the inlet pipeline does not meet the requirements of the specification and the flow pattern is turbulent of an irrigation pumping station in the lower reaches of the Yellow River. Hydraulic loss and uneven distribution of water flow field at the outlet of the inlet pipe (pump inlet), causing overpowered operation of the pump unit, cavitation and vibration of the pump, and harsh noise. In severe cases, the blades are broken and the pump unit cannot work, which poses a threat to the personal safety of the pump station staff, and urgently needs technical upgrading and transformation. 【Objective】 Aiming at the problems of the unreasonable layout of the inlet pipeline of a pumping irrigation pumping station in the lower reaches of the Yellow River, the water inlet pipeline of the pumping station was technically transformed in response to problems such as the deterioration of the water flow at the inlet of the pump, the fracture of the pump blades, the vibration of the pump unit, and the overload operation. 【Method】 The NS equation of three-dimensional incompressible fluid and the standard k-ε model were used to numerically simulate the hydraulic characteristics of the inlet pipeline before and after the transformation, and the flow velocity distribution and streamline distribution of different sections of the inlet pipeline under five flow rates were analyzed. Alos, the velocity distribution uniformity, pipeline hydraulic loss, pipeline vorticity distribution and vorticity value of the outlet (water pump inlet) section were analyced. 【Result】 After the transformation, the hydraulic loss of the inlet pipeline was reduced by 78.96% on average, and the maximum positive and negative vorticity values were reduced by 83%~84% on average; the flow pattern and vortex distribution of the inlet pipeline tended to be uniform, and the water flow in the inlet pipeline was stable. The average flow velocity is 1.57~1.93 m/s, which met the requirements of the specification; The uniformity of the flow velocity distribution of the outlet section of the inlet pipe increased by 4.48% on average, which effectively improves the pump inlet conditions. 【Conclusion】 The hydraulic characteristics of the inlet pipeline of the pumping station after the renovation have been improved, and the active power of each unit is reduced by 35 kW, which has obvious energy-saving effects, which can provide a reference for similar renovation projects.

In order to improve the effective utilization of agricultural irrigation water and to reasonably allocate water resources in irrigation areas, it is necessary to use open channel flow measurement devices that are accurate and easy to carry. In this study, a spring-plate flow measurement device with different plate widths was designed. Through a combination of theoretical analysis and numerical simulation, the measurement characteristics of the device in specific channels under conditions of 20–105 m3/h flow were studied, the relationship between the flow rate and the force acting on the plate surface was fitted, and the hydraulic characteristics of water flow during its use, such as pressure, velocity distribution, and head loss, were analyzed. The results show that in the process of using the spring-plate flow measurement device, the force on the plate surface increases with the increase in the flow rate, and the force on the plate surface is related to the flow rate in the channel by a power of 5/6. The width of the measurement plate impacts the accuracy of flow measurement, and the smaller the plate width, the larger the error in flow measurement. The distribution of pressure on the measurement plate is similar to that of static pressure, and the pressure increases with the increase in the width of the measurement plate. The upstream flow velocity of the device is small, and the water level increases due to obstruction of the measurement plate. When it connects to the downstream water surface, the water level rapidly decreases, and the flow velocity increases. In using the spring-plate flow measurement device to measure flow, head loss will be produced, and the magnitude of this loss increases with the increase in the width of the measurement plate. The research results provide a theoretical basis for the application of spring plate flow-measuring devices in irrigation areas.

To improve the efficiency of waste collection in recirculating aquaculture tanks (RATs), this study proposed a dual-channel RAT with flow-guide discs on the overflow pipe close to the bottom. First, an experimental verification system was designed, and the validity of the two-phase flow model was verified by comparing the experimental results. Then, the liquid solid flow characteristics were analysed by comparing the velocity distribution, particle trajectory, retention time and removal rate. Finally, the influences of the parameters of the flow-guide discs on the particle agglomeration effect were obtained by comparing the discharge rate of particles under different hydraulic retention times (HRTs). The results indicate that the flow-guide disc weakens local reflux, reduces the overcurrent area and the low-speed vortex area at the bottom of the tank, and thus shortens the residence time for particulate matters. As the diameter of the flow-guide disc increases within a certain range, the flow velocity gradient and eddy intensity near the disc will increase, resulting in a shorter residence time for particles. Furthermore, as the height of the flow-guide disc to the bottom of the tank decreases, the flow velocity below it accelerates, which is beneficial for improving the discharge rate of particulate matter. However, when the height of the flow-guide disc increases to a certain extent, the influences on the hydrodynamics of waste collection become weaker. • A design pattern for a aquaculture tank was proposed, which installed a flow-guide disc on the overflow pipe close to the bottom of the tank. • A two-phase flow numerical method was proposed to study the hydrodynamics and self-purification efficiency for tanks. • The effects of the flow-guide disc on the flow field, particle trajectory, residence time, and discharge rate of the tank were obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] When power is off, the flow rate of coolant in the RCP decreases rapidly and irregular phenomena appear. However, the inflow coolant tends to be uneven and unsteady due to the design of coolant pool. To simulate the actual situation of pool-type RCP under flow coast-down, Circulation-loop model and Open-border model were established. It provides two prediction methods of the power-off condition of pool-type RCP. The flow rate of Open-border model drops synchronously with rotation speed, and that of Circulation-loop model is dynamically fed back through calculation. Variation trends of external characteristics of the two models are similar. However, it is found that a large-scale and low-speed vortex appears at the horizontal suction part of the pool in Circulation-loop model, blocking the coolant transport channel. Thus, there is obvious fluctuation and hysteretic nature phenomenon in the decline of flow rate compared to the decline of rotation speed in Circulation-loop model. [ABSTRACT FROM AUTHOR]

Sufficient air concentration on aerated spillway flows can mitigate the hazard of cavitation damages on concrete surfaces of spillways. In this study, a three-dimensional two-phase flow is modelled numerically and hydraulic characteristics and air concentration over the Gavoshan dam spillway is investigated as a case study using different discharge rates. The discretization of Reynolds-Averaged Navier–Stokes (RANS) equations have been carried out by Finite Volume Method (FVM) and Volume of Fluid (VOF) method has been used to distinguish the air–water interface. The k-ε turbulence model is applied to simulate the turbulent flow on the chute and aerator. The outcomes of the study show that there are no significant differences between physical and numerical model results. Presence of aerator causes the cavitation index to increase more than the absence case. As the discharge rate increases, pressure differences between the inner cavity formed immediately downstream of the ramp and the atmosphere increases proportionally. Increasing discharge rate results in air concentration decrement of flow downstream of the aerator. Due to Froude number increment, by decreasing the discharge rate, the aeration coefficient and the air concentration over spillway surface increase. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the crucial influence of the width of dam gate and its position, as well as initial water depth, on the evolution of rarefaction waves on reservoirs, and of shock waves over dry flood plain areas. The large eddy simulation (LES) model and volume of fluid (VOF) method are used to simulate three objectives. Firstly, validation of the presented numerical model, and of mesh sensitivity analysis, are conducted by means of a physical test case, taken from the literature, showing very good accuracy with a small value of RMSE among all hydraulic features in the case of fine mesh. In this direction, the 3D result is also compared with the published 2D one, to prove the necessity of using a 3D model in performing dam–break flow in an early stage. The second aim is to look for insight into the following 3D hydraulic characteristics of dam–break flow: water depth, velocity hydrograph and streamline, vorticity, the q–criterion incorporated with variety of breach size, initial water stage and the reservoir outlet's location. The influence of the dam gate's place on peak discharge is pointed out by means of a 3D model, while the existing analytical solution is not specified. With the same conditions of initial water depth, breach width and geometry, an analytical solution gives the same peak discharge, while a 3D numerical one indicates that a symmetrical dam gate provides a greater value than does the asymmetrical case, and also a value greater than that of an analytical result. [ABSTRACT FROM AUTHOR]

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The water filling process is one of the typical operation conditions of long-distance water transfer tunnel. In view of the realistic demand of safety dispatching in the initial operation of Hanjiang-to-Weihe River Diversion Project, the hydraulic transition process of the first water filling was studied and the dispatching model of water conveyance tunnel was established. The virtual flow method was used to solve the problem, and the numerical simulation was carried out for two working conditions of increasing water supply area and ensuring water supply area, and the first filling characteristics of different water supply flow were analyzed. The results show that when the water supply flow of the first filling is 70 m³ / s and 18 m3/s respectively, the first end (pile No. 0+000), 1/4 mile (pile No. 20+450), midpoint (pile No. 40+ 900), 3/4 mile (pile No. 61+350) and Huangchigou flow and water depth increase steadily. There will be no bright full flow or tunnel empty and other adverse phenomena. [ABSTRACT FROM AUTHOR]

To improve the efficiency of low-head pump device in the large-discharge and low-head domain, the hydraulic characteristics of vertical axial flow pump devices with different guide vane inlet angles were studied using computational fluid dynamics (CFD) and model test methods. The Q∼Hzz and Q∼ηzz curves of the pump device were obtained for different impeller blade angles when the inlet angle adjustments of the guide vane were 0° and −12°. The resulting hydraulic performance was compared and analyzed. The results showed that the pump device efficiency under low-head and large-discharge conditions was improved when the guide vane inlet angle was rotated in the clockwise direction. The reason for the increased pump device efficiency was analyzed using CFD. When the guide vane inlet angle adjustments were 0° and −12° under low-head working conditions, the vortex in the guide vane was eliminated, the hydraulic loss of the guide vane decreased, and the energy performance of the pump improved. When the operational conditions of the pump device deviate from its high-efficiency zone due to limitations in the pump model or the motor itself, the application of these results could improve its hydraulic performance, which is of great significance to the design and application of low-head pump devices.

Copyright of Mountain Research (10082786) is the property of Mountain Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study identifies the hydraulic efficiency of a novel onsite sanitation system at variable hydraulic shock loading conditions. The system consisted of three chambers, each working as an up-flow anaerobic bioreactor, accommodated within a single unit. The hydraulic characteristics were identified with the help of residence time distribution (RTD) analysis by step feeding of lithium chloride (LiCl) solution into the system. The experiments were run at variable hydraulic loading conditions at different peak flow factors (PFF) of 1, 2, 4 and 6 while maintaining 24-h hydraulic retention time. As revealed in the RTD analysis, the biofilm reactor achieved a very good hydraulic efficiency that varied from 0.76 to 0.81 at PFF 1, 2 and 4. Although in the case of PFF6, it was comparatively low. It was noted that the dispersion number was always below 0.2 at variable hydraulic shock loading conditions under different PFFs, which indicated that the reactor behaved perfectly between mixed-flow and plug-flow reactor. The system was also able to achieve good pollutant removal efficiency for chemical oxygen demand (COD) and total suspended solids (TSS) under all PFFs, which was more than 68 and 75%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Hydraulic performance of Continuous Flow Left Ventricular Assist Devices depends on their pressure head and flow rate relations. Hydraulic characteristics of these devices are expressed by pressure head and flow rate loops in a pulsatile environment as they are implanted between left ventricular apex and aorta. Nonetheless, constant speed Continuous Flow Left Ventricular Assist Device support causes complications due to altered blood flow in the patients' body. Therefore, beat-to-beat varying speed Continuous Flow Left Ventricular Assist Device support algorithms have been proposed to operate these devices in synchronized co-pulsating or counter-pulsating modes which can generate more physiological blood flow in the circulatory system. However, the effect of speed variation on the pressure head and flow rate loops remains unclear during varying speed Continuous Flow Left Ventricular Assist Device support. In this study, pressure head, flow rate and operating speed relations during co-pulsating and counter-pulsating pump support in a Continuous Flow Left Ventricular Assist Device were analyzed utilizing numerical simulations. Simulation results show that pressure head - flow rate - operating speed loops can express Continuous Flow Left Ventricular Assist Device characteristics better during varying speed heart pump support. Moreover, pump flow rate - operating speed and pressure head - operating speed diagrams show the dynamic behavior of a heart pump, including also the speed. Therefore, understanding the relationship between speed, flow rate and the pressure difference across a pump may help to develop novel beat-to-beat operating modes to improve Continuous Flow Left Ventricular Assist Device support.

Because of climate change, the erection of dams through transboundary rivers, and the shortage of water resources, countries worldwide are facing several challenges. Unconventional water resources such as recycling wastewater are urgently needed to overcome the demand–supply gap. The bioreactor is considered an effective means of removing contaminants and enhancing the self-purification on open waterways. This study numerically investigates the hydraulic impacts of an installed bioreactor in an open channel. Three-dimensional numerical models were developed based on computational fluid dynamics (CFD) to simulate different arrangements of the gravel bioreactor installed in the open channel. The relative heading up increased as Froude’s number increased, regardless of the number of bio-filter segments. The heading up values decreased significantly when dividing the bio-filter into several segments with the same total length. The relative heading up decreased linearly as the distance between the bio-filter segments increased for a constant bio-filter length. On the other hand, the relative heading up increased linearly as the length of the bio-filter segments increased for a constant inter-distance of the bio-filter segments. For simultaneous changes in both the length of the bio-filter segments and their inter-distance, the relative heading up increased nonlinearly with the product of both the length and inter-distance. This study confirmed that the greater the inclination angles of the bio-filter’s face, the greater the heading up. When considering the base case with the inclination angle of 45°, the increasing ratios of the relative heading up were 14.5%, 16.1%, and 19.7%, corresponding to the angles 60°, 75°, and 90°, respectively.

Hydraulic pipeline transportation of a piped vehicle is a new mode of transportation with energy-saving potential and environmental protection. In order to analyze the turbulent characteristics of the flow around the piped vehicle, a large eddy simulation (LES) method was adopted to simulate the hydraulic characteristics and vortex characteristics of the flow at a Reynolds number of Re = 140,467 with diameter-to-length ratios of 0.4, 0.5, 0.6, and 0.7. The results showed that the main factor that affected the gap flow velocity, the backflow area length, and the turbulence intensity was the cylinder diameter in the diameter-to-length ratio of the piped vehicle. The backflow area lengths for piped vehicles with different diameter-to-length ratios were all less than 1 D, and the axial disturbance distances were about 7.5 D. In addition, a variety of vortex structures existed in the gap flow and the rear flow areas. At the beginning of vortex development, ring vortices were generated at the front and rear ends of the cylinder body. Subsequently, the front ring vortex fell off along the cylinder body and evolved into hairpin vortices. At the same time, a reflux vortex was formed after the rear ring vortex broke away from the cylinder body, and wake vortices were generated behind the rear supports. Finally, some worm vortices were dispersed from the wake vortices. These results can further improve the theoretical system for the hydraulic pipeline transportation of piped vehicles and can provide a theoretical basis for industrial application.

Scientific assessment of the hydrodynamic conditions of water system connection is of great significance and value in guiding the ecological construction of urban water system connection and building healthy river–lake relationship. Based on the advantages of SWMM in effectively simulating urban rainfall and surface runoff, a hydrological and hydrodynamic model was constructed before and after the implementation of urban water system connection project, and the model was applied to the analysis of rainfall and flooding processes in two recurrence periods of 5a and 10a after the implementation of urban water system connection in Pingyu County. The results show that the initial flow rate and velocity of river cross-section increased in the same recurrence period after the water system connection, the maximum increase of water exchange capacity was 115.56%, the peak flow rate and velocity were weakened and the peak time was lagged, and the hydrodynamic conditions were improved significantly. [ABSTRACT FROM AUTHOR]

To make more efficient use of limited space, improve the energy dissipation effect of the step dissipator, and mitigate the effect of cavitation, we propose a segmented pier-type step dissipator structure and used a numerical simulation to study the hydraulic effects of two different arrangements of piers: a double-row arrangement and a staggered arrangement. We’ve drawn the following conclusions from our study: the segmented pier-type structure produces a large water jump at the location of the energy dissipation pier. This involves a large amount of air, promotes air-doping of the water flow in the whole section, and reduces the length of the non-air-doping zone. The staggered pier arrangement produces a better air-doping effect at the water jump and a higher air-doping concentration along the water course. The staggered arrangement also produces a better cavitation mitigation effect and is better able to stabilise the water flow; the flow velocity at the outlet is lower, so the energy dissipation effect is better. A larger positive pressure area forms at the headwater and upstream areas of the energy dissipation pier; a larger negative pressure forms at the top and backwater of the energy areas. The staggered arrangement produces a larger negative pressure; however, under various flow conditions, the difference in the energy dissipation rate between the two forms of pier arrangements is not significant. We obtained a peak energy dissipation rate of 90.04%, which represents an improved energy dissipation effect compared with the control. The step energy dissipator described here is conducive to stabilising the outlet flow, reducing cavitation damage, and improving energy dissipation. These findings provide a valuable reference for the future design of sectional pier-type step energy dissipator structures.

The pumping station is an important part of the agricultural irrigation and drainage system. The sump is one of the common water inlet types of agricultural pumping stations. In the sump, to facilitate the installation and maintenance of equipment, some hydraulic structures, such as pump beams, maintenance platforms and chest walls, are added to the sump. At present, the impact of hydraulic structures in the sump on the hydraulic performance of the pump device is not clear, so this paper focused on the impact of hydraulic structures on the hydraulic characteristics and entropy generation characteristics of the pump device by using numerical simulation methods. The results showed that the installation of hydraulic structures in the sump has the greatest impact on the efficiency of the pump device. The efficiency coefficient increased after adding a pump beam in the sump and decreased by about 2% after adding a maintenance platform and a water retaining chest wall. Results also showed that the installation of hydraulic structures in the sump will lead to uneven distribution of entropy generation in the sump, especially in the vicinity of the hydraulic structures. The installation of the maintenance platform and chest wall will lead to the increase of the total entropy generation in the sump, which also means that the hydraulic loss in the sump will increase accordingly. Hence, in addition to the pump beam, other structures should be avoided in the sump.

Copyright of Journal of Henan University of Science & Technology, Natural Science is the property of Editorial Office of Journal of Henan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biological soil crusts (biocrusts) are the common living skin of the land face in arid and semiarid regions. They greatly change the hydropedological features and soil-water movement of surface soil. But the influencing mechanism is still lacking, especially on water infiltration and retention. Taking the Loess Plateau of China as a study area, this study aims to explore the effects of moss-dominated biocrusts on the fundamental parameters in the surface soil-water movement, with emphasis on the characteristics of water infiltration and water retention. The moss biocrusts (naturally developed for > 30 years) and uncrusted soil formed on the aeolian sandy and loess soil were firstly collected in the Liudaogou watershed in the northern Loess Plateau. Afterwards, four treatments were carried out to measure the parameters of Boltzmann transformation, soil water diffusivity, infiltration, specific water capacity, and unsaturated hydraulic conductivity on-site or in the laboratory after sampling. A comparison was finally made on the soil-water movement parameters between the biocrusts and uncrusted soil. The results showed that the biocrust layer impeded the horizontal movement of surface soil water both in the aeolian sandy and loess soil. Specifically, the Boltzmann transformation parameter and soil water diffusivity of biocrusts decreased by 7.9%–27.3% and 30.5%–63.9%, respectively, compared with the uncrusted soil. Moreover, the biocrusts highly decreased the water infiltrability of surface soil, subsequently the whole soil profile. The initial, stable, and average infiltration rates of biocrusts decreased by 37.0%, 34.1%, and 19.9%, respectively, whereas, the cumulative infiltration amount and unsaturated water conductivity of biocrusts decreased by 33.4% and 88.6%, respectively, compared with the uncrusted soil. Additionally, the mean values of soil water parameters (including saturated water content, field capacity, wilting point, gravitational water content, available water content, and readily available water content) and specific water capacity at soil suction of 100 kPa of biocrusts were 5.2%–1233.3% and 7.4%–1540.5% higher than that of the uncrusted soil, respectively, implying that the biocrusts greatly improved the soil water holding capacity and availability. Most importantly, the low infiltrability and high water holding capacity of moss biocrusts were closely related to the contents of sand and silt, as well as the organic matter in the biocrust layer. The biocrusts that developed on the aeolian sandy soil presented weaker effects on the soil infiltrability, but stronger effects on the water retention and availability, compared with the biocrusts on the loess soil. The reason was that there was a 1–2 cm thick layer with particular properties (e.g., soil texture, organic matter content, and bulk density) in the moss biocrusts. Therefore, the availability of soil water increased greatly, whereas, the diffusivity and infiltrability decreased significantly in this case. Consequently, the biocrusts can possibly make the upper soil (such as 0–50 cm) retain more water, while inhibiting the water infiltration into the deep soils after rainfall. Subsequently, the availability of soil water can be altered for the water use strategy of vegetation in fragile arid and semiarid ecosystems of the Loess Plateau. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Unusual flow characteristics such as reverse flow, rotating stalls, flow recirculation, and stationary vortexes can induce high dynamic forces and torque variations on the entire system, creating a positive slope in the discharge-head curve. To avoid these problems, the present study investigates the hydrodynamic characteristics of a lab-scale model of a Francis type pump-turbine unit in the transition region. To verify the simulation, its results were compared with those of a laboratory-scale experiment performed over various operating ranges. The differences between the experimental and numerical speed, discharge, and torque factors were compared. The numerical analysis was well-matched the experimental tendencies in the overall operating and transition regions. The reliability of the simulations was within 4%. The unsteady RANS equations in the SAS–SST model were discretized for a detailed analysis of the pressure and internal flow characteristics. Under the runaway condition and low-discharge conditions, the frequency spectra of the pressure fluctuations were remarkable at low-frequency related to the rotating stall and blade passing frequency. These results represent a rotating stall with a frequency propagation of approximately 60% of the rotational speed of the runner. In case of the internal flow field, some blade loading distributions developed a positive shape while others developed a negative shape under the runaway condition. Although a rotating stall formed under the low-discharge condition, the form under this condition differed from that developed under runaway conditions, owing to backflow and the single stall cell. • The unstable S-shaped characteristics in a lab-scale model were studied. • The numerical results were validated in comparison to the experimental data. • The location and rotating speed of stall under the S-curve region were observed. • The unsteady pressure characteristics were analyzed with internal flow field. [ABSTRACT FROM AUTHOR]

The optimization of heating metering method in the heating season has very important and practical value for energy saving and emission reduction, however, existing studies haven’t comprehensively analyzed the heating metering and charging management systems adopted by residential buildings with adjustable heat supply, and the problem of fair heat sharing hasn’t been well solved yet. To fill in this research gap, this paper designed an individual household-based heating metering and charging management system. At first, the paper gave the structure of the system and introduced the system functions, then, it analyzed the hydraulic characteristics of the heating system and the influence on the heat dissipation volume of the radiator, and constructed the heating metering and heat distribution model. At last, the paper proposed a scheme for heating metering and heat sharing in cases of normal operation and on-off heating adjustment of individual household radiator, and the effectiveness of the proposed scheme was verified via experimental results. [ABSTRACT FROM AUTHOR]

• SY and Sr of the SL was the largest, but the sediment MWD was the smallest. • Change in the flow discharge did not affect the distribution pattern of sediment particles. • Dynamic coupling of runoff hydraulics and EG morphology drove soil loss. • SDR was the most direct influencing factor on the Sr in EGs. Ephemeral gully (EG) erosion represents the early stage of large-scale gully (locally named as "Benggang") development on Ultisols in the granite hilly area. However, the EG erosion process and the mechanism underlying sediment production have not been fully elucidated. In this study, a series of field scouring experiments were conducted under different flow discharge levels (10, 15, 20, 25, and 30 L·min−1), and the primary EGs in three typical soil layers with different weathering degrees (red soil layer (RL), transition layer (TL), and sandy layer (SL)) was dynamically monitored. The results indicated that the ratio of width to depth of the EGs rapidly decreased as the flow discharge increased. At 30 L·min−1, the average sediment yield and transport rate (Sr) of the SL were 4.85 and 5.39 times, greater than those of the RL, respectively. The sediment particles were concentrated within the 1–2 mm particle size range, accounting for over 35 %. In addition, the mean weight diameter of the sediment particles in the RL was the largest. The sediment distribution characteristics did not respond to flow changes but were affected by EG morphological changes. With increasing flow discharge, the flow shear stress and stream power increased. Further analysis revealed that the coupling effect of flow hydraulic characteristics and EG morphological evolution drove the EG erosion sediment production process, and the Sr of the SL was highly sensitive to flow discharge changes. The soil disintegration rate was an internal factor that directly affected soil loss in the EGs, with a path coefficient of 0.71. The bulk density, organic matter content, and sand content were all indirect influencing factors. The RL exhibited greater anti-erodibility than the other layers and could serve as an effective protective layer for granite hilly areas. These findings provide a theoretical basis for improving soil loss management systems. [ABSTRACT FROM AUTHOR]

This study includes determining the hydrogeological setting of the aquifer in the study area including groundwater measurement direction and the hydraulic characteristics of the aquifer. The study showed the existence of a shallow aquifer (unconfined) in the Quaternary deposits with presence of confined aquifer in the Bai-Hasan Formation. The construction of flow net showed that the groundwater flow is from the northeast to southwest (middle parts) of the study area and then to northwest towards the Lesser Zab River. The information of six wells three of them with observation well shows that the values of the transmissivity (T), hydraulic conductivity (K), Storage Coefficient (S) and specific capacity (SC) were ranged from (12.048 to 158.559 m3/day/m), (0.0848 to 4.545 m/d), (2.1 × 10-4 - 4.67 × 10-3) and (21. 6 to 166.956 m3/d/m) respectively, where (T) and (K) calculated by using (Aquifer Win program) software that depend on the methods of Cooper-Jacob and Theis recovery for analysis these information. The saturated thickness values for each wells collected from bank information of General Commission for Groundwater Kirkuk branch is ranged between (33 – 142) m. The aim of the research is to calculate the hydraulic characteristics and the flow direction, as well as the renewable and constant storage and the distance between the drilling wells in the study area..

Gypsum aggregate specimens have been used in the present study, because brittle, semi-brittle and ductile stress-strain behaviors of the specimen can be controlled only with confining stress level at the room temperature. At confining stresses up to 40 MPa, tri-axial compression and fluid flow experiments have been conducted on the intact specimens and single fracture specimens. It has been indicated that stress-strain behavior is independent of existence of fracture. Moreover, permeability of the single fracture specimen is much higher than intact specimen at conditions of brittle, semi-brittle, intermediate state between semi-brittle and ductile and ductile condition. On the other hand, permeability of the single fracture specimen is not so different from that of the intact specimen at conditions of a transitional behavior between semi-brittle and ductile stress-strain behaviors. As for the geothermal reservoir in the semi-brittle and ductile region, it was suggested that the fracture is retained and permeability is maintained when fracturing occurs due to hydraulic crushing or the like.

The water inlet channel is an essential component of the thermal power plant’s circulating water system. It primarily arranges the water flow in the channel so that it is introduced into the pump room smoothly, steadily, and uniformly. Significantly, the operation state of the circulating water pump is impacted by the flow condition of the water inlet channel. The coal-fired generating set’s water input channel was chosen as the research object in this work, and the Computational Fluid Dynamics (CFD) Method was used to examine hydraulic issues impacting anomalous vibration of circulating pumps. Nine optimization options were also suggested, and the effects of the various plans on the water inlet channel’s flow state were examined—the simulation’s outcomes. The simulation’s findings indicate that the arc deflector can enhance the water entry channel’s flow pattern. The wall-attached bias flow of the suction chamber vanished, and the constant flow state is present around the pump’s bellmouth. The thermal power unit’s circulating water pump’s vibration was eliminated, and the circulating pump’s operating efficiency increased due to the curved deflector’s rectification procedures being implemented in the forebay. The study’s findings can guide the hydraulic performance optimization of channels for water inlets with similar sideways or high slopes.

The leaching of material from concrete fracture surfaces has an impact on the structural concrete in service, but the number of studies that consider the effect of the coupling of the leaching, fracture geometry and hydraulic processes on concrete fractures is insufficient. In this study, a series of experiments was conducted, and a leaching model proposed, to investigate the mechanism of leaching behavior on the geometric and hydraulic characteristics of concrete fractures. Following the leaching experiment, the evolution of fracture geometric characteristics was observed by a three-dimensional (3D) laser scanning technique, finding that the fracture produces residual leached depth and local uneven leaching, which results in a decrease in roughness. The hydraulic characteristics were then investigated by permeability tests, and it was found that the fracture hydraulic aperture and permeability increase monotonically with leaching time. A simulation of fluid flow in a numerical fracture revealed the effect of residual leached depth and a decrease in roughness on the hydraulic characteristics. Finally, based on the analysis of the chemical composition of the leaching solution, a leaching model of concrete rough fracture surface is proposed and the mechanism of leaching behavior is discussed. These new findings are useful for the understanding of the development of leaching, local to concrete fracture surfaces.

Based on the Reynolds time mean N-S equation and standard k-ε turbulence model and using Computational Fluid Dynamics technology, this study aims to integrate the brake pump to carry out numerical simulation. Through the adoption of different arrangements of impending height and spacing, the hydraulic characteristics of the full tubular pump unit are analyzed. The two-dimensional streamline, velocity and pressure distribution, and three-dimensional streamline, axial velocity and vorticity distribution of the front pool of each scheme are displayed. The results show that the recommended pump installation height is 0.8 Dd, the maximum limit value of the pump station design specification; in the dual-pump mode, the recommended pump spacing is 2.00 Ds.