Water Velocity Research Articles

Design, construction, and field testing of a spiral water wheel pump

The global expansion in farmland and the increase in the world population has compounded the need for more efficient water use. The spiral water wheel pump can be a valuable and low-cost option for pumping water for surface and subsurface irrigation for farmland near flowing water bodies. This low-cost water-lifting device, which uses the kinetic energy of a flowing stream/river to lift water to homes and farmlands, can help smallholder farmers expand the growing season into the dry season. It is more cost-effective than conventional energy sources. It can be used in areas with limited access to electricity or fossil fuels because the energy of pumping is derived from the kinetic energy of flowing water. Its simplicity, adaptability, and low maintenance requirements make it a valuable tool for communities seeking water security and improved livelihoods. The main objective of this study was to develop performance curves for a version of the pump fabricated from polyvinyl chloride (PVC) and wood, materials that are readily accessible to smallholder farmers in Africa, to optimize its performance for different field conditions. Laboratory and field tests were performed in Illinois, United States of America, and Sierra Leone, West Africa, with pumps with several pipe diameters/pipe configurations and wheel diameters. During the laboratory tests, a 0.6m diameter single-layer pump with a 2.5cm pipe diameter (18 coils) lifted water to a maximum height of 3.4m. When a 3.8cm pipe diameter (10 coils) was used, the maximum height was reduced to 2.7m. Field tests at an experimental site in Fulton County, Illinois, generated a maximum height of 3.4m and 3.1m when 2.5cm pipe diameters were used on 1.22m and 0.6m diameter wheels, respectively. In Sierra Leone, the maximum height generated was 16m and 8.5m for the 1.22m and 0.6m diameter wheels, respectively, with a 1.9cm pipe diameter. In all the field tests, the pumps only worked when the water velocity exceeded 0.6 ms-1, smaller streams with a velocity less than 0.6 ms-1 can be channeled if necessary. These results indicate that this pump can improve dry season productivity for farmland near the flowing water bodies in developing countries like Sierra Leone. Key words: Wheel diameter, pipe diameters, pipe configuration, discharge rate, stream velocity

Impact of the comprehensive remediation project on hydrological conditions in the lower reaches of the Ganjiang River.

This study undertakes a systematic analysis of the hydrological changes before and after the implementation of the Comprehensive Remediation Project in the lower reaches of the Ganjiang River. It focuses on changes in downstream inflow, ratios of flow distribution, and water levels, as well as water velocity near the gates. The results indicate a significant improvement in the spatial distribution of water resources in the lower reaches of the Ganjiang River. The project enhances the inflow from the northern and southern branches, positively influencing downstream water usage and the ecological environment. Building upon these findings, the study proposes operational recommendations tailored to different hydrological years, such as timely adjustments to the southern branch's water inflow and optimizing flow distribution ratios. This research provides a scientific basis for the implementation and dispatch of comprehensive remediation projects and offers insights into water resource management in similar regions.

Surface water quality modelling with data scarcity in semi-enclosed coastal regions encompassed distributed islands

Water quality variation in semi-enclosed urban coastal areas with different pollutant sources is a substantial issue. Pollutant entrapment has a significant impact on the lives of the local people. Surface water quality modelling often requires large datasets covering bathymetry, fluid and pollutants boundary conditions, sources and sinks. This is particularly challenging in regions with complex features and poor data availability, such as coastal water bodies featuring a large number of widely distributed islands and estuaries. In this paper, we developed a model of surface water quality and hydrodynamics for Ha Long Bay, in the North of Vietnam and includes 1969 islands, for a one-year period using a water quality dataset obtained for this study. The model utilized extracted bathymetric and geometric data from Admiralty Charts and Admiralty Tide Tables. Water quality coupled with the TELEMAC Model (WAQTEL) Biomass Module was employed to predict pollutant transport in the domain using point and diffused sources while field studies were conducted to collect data for the setting up and calibration of the water quality model. Thirty scattered sampling points were selected, and the water quality parameters were measured during two campaigns. The predicted water level and velocity values matched the local observation data well with a small error (RMSE = 0.19 and 0.16). Both NO3−-N and PO43--P were high near the shoreline and decrease gradually offshore. The maximum concentrations of NO3−-N and PO43--P reached 0.476 mg/L and 0.048 mg/L at the end of 2021 with the RMSE = 0.13 and 0.011, respectively. The levels of NO3−-N and PO43--P and their distributions showed that Ha Long Bay was eutrophic even during the COVID-19 lockdown period.

Modelling the piping-assisted erosion of clay barriers

Recent laboratory and field experiments have provided evidence of the erosion and piping of clay-based barriers. Predicting these phenomena is essential for the performance assessment of bentonite barriers and containments. This paper presents a non-local multi-physics model for bentonite erosion induced by piping flow that includes swelling, detachment of particles and co-transport of detached particles with piping flow. The erosion is controlled by the balance between the cohesive strength, which depends on the swelling, and the shear force, which depends on the water velocity and chemistry. The accuracy of the model is tested by comparison of simulation results with experimental data from pinhole tests and material erosion in boreholes. It is demonstrated that the model predicts accurately the total mass eroded by the piping flow. For example, the results show that the mass loss induced by piping-assisted erosion during the installation of a bentonite plug can reach 10·3% of the original mass, which may significantly reduce the sealing capacity of bentonite plugs in boreholes. The results of simulations show that the eroded mass depends on the borehole diameter and flow rate. The minimum flow rates required to erode 10% of the original mass are 0·8 l/s and 0·045 l/s for borehole diameter, db = 56 mm and 160 mm, respectively. These results demonstrate how the proposed formulations can be used to quantify the piping-assisted erosion of clay barriers, such as buffers, backfills and plugs considered for geological disposal of higher activity waste, and the sealing of investigation boreholes and abandoned geo-energy wells.

Simulation and experimentation of Propeller-Savonius turbine tested underwater surface

Abstract Indonesia’s vast maritime territory offers a unique opportunity for harnessing the potential Energy of seawater currents. This study explores the effectiveness of a combined Savonius and propeller-type turbine system. The Savonius turbine, known for its efficiency in capturing ocean currents due to its large sweep area, is combined with a propeller-type turbine to enhance rotational speed and power generation. A novel approach is employed to induce turbulence and optimize energy extraction, first channeling water through the propeller turbine and then into the Savonius turbine. A comprehensive investigation is conducted through simulations and experimental tests within a controlled tunnel environment. The study explores the performance of two-bladed and three-bladed Propeller-Savonius configurations at varying inlet water velocities (0.1, 0.3, 0.6 and 1.0 m/s). The simulation incorporates a turbulence model with 5% intensity and a hydraulic diameter of 0.216 m. Results indicate that the proposed configuration achieves a maximum power output of 2.0293 W with an impressive efficiency of 63.339% in simulation. Concurrently, experimental testing yields a peak efficiency of 61.335% and turbine power of 0.3951 W. The findings demonstrate the feasibility of the combined turbine system and highlight the importance of turbulence in optimizing energy extraction from seawater currents. This research contributes valuable insights into the design and performance of hybrid turbines for harnessing oceanic Energy, emphasizing the potential for sustainable power generation in maritime regions. The methodology and results presented herein offer a foundation for further exploration and refinement of seawater current energy conversion technologies.

Variables influencing stream‐type juvenile Chinook Salmon density within floodplain habitat in the Skagit River basin, Washington

AbstractObjectiveDespite decades of restoration work, Chinook Salmon Oncorhynchus tshawytscha in the Pacific Northwest remain under the protection of the U.S. Endangered Species Act (ESA). Chinook Salmon in the Skagit River basin play a vital role in the abundance and recovery of the Puget Sound Chinook Salmon Evolutionarily Significant Unit, which is currently listed as threatened under the ESA. The stream‐type juvenile (STJ) life history pattern of Chinook Salmon in the Skagit River has higher ocean survival to the adult stage (i.e., productivity) than that of parr or fry out‐migrants, and improvement in STJ Chinook Salmon habitat could increase abundance and diversity in the Skagit River basin. Our objective was to provide recommended ranges of variables shown to influence habitat selection in floodplains by STJ Chinook Salmon.MethodsUsing field observations from 70 sites within the Skagit River basin, we developed generalized linear mixed‐effects models across three seasons in floodplain habitats to correlate variable ranges with densities of STJ Chinook Salmon.ResultModel accuracy varied by season (summer: R2 = 0.24; winter: R2 = 0.56; spring: R2 = 0.54), and significant parameters included velocity, substrate, depth range, and distance to the closest connection with the main stem. Additional significant factors included wood cover, maximum water temperature, velocity range, and interaction of the ranges of velocity and depth. Recommended ranges for habitat variables associated with the highest densities of STJ Chinook Salmon include depths of 40–68 cm, velocities of 0.06–0.33 m/s, substrate sizes of 3–36 mm, and distances of 33–119 m to the main‐stem connection. Water temperatures associated with high juvenile densities varied by season (winter: 4–6°C; summer: 9–14°C).ConclusionOur recommended ranges for habitat variables can be used to refine designs for river restoration projects intended to improve habitat for juvenile Chinook Salmon and other salmonids in the Pacific Northwest.

Comparison of Gas Signature and Void Fraction in Water- and Oil-Based Muds Using Fiber-Optic Distributed Acoustic Sensor, Distributed Temperature Sensor, and Distributed Strain Sensor

Summary Accurate estimation and prediction of gas rise velocity, length of the gas influx region, and void fraction are important for optimal gas kick removal, riser gas management, and well control planning. These parameters are also essential in monitoring and characterization of multiphase flow. However, gas dynamics in non-Newtonian fluids, such as drilling mud, which is essential for gas influx control, are poorly understood due to the inability to create full-scale annular flow conditions that approximate the conditions observed in the field. This results in a lack of understanding and poor prediction of gas kick behavior in the field. To bridge this gap, we use distributed fiber-optic sensors (DFOS) for real-time estimation of gas rise velocity, void fraction, and influx length in water and oil-based mud (OBM) at the well scale. DFOS can overcome a major limitation of downhole gauges and logging tools by enabling the in-situ monitoring of dynamic events simultaneously across the entire wellbore. This study is the first well-scale deployment of distributed acoustic sensor (DAS), distributed temperature sensor (DTS), and distributed strain sensor (DSS) for investigation of gas behavior in water and OBM. Gas void fraction, migration velocities, and gas influx lengths were analyzed across a 5,163-ft-deep wellbore for multiphase experiments conducted with nitrogen in water and nitrogen in synthetic-based mud, at similar operating conditions. An improved transient drift flux–based numerical model was developed to simulate the experimental processes and understand the gas dynamics in different wellbore fluid environments. The gas velocities, void fractions, and gas influx lengths estimated independently using DAS, DTS, and DSS showed good agreement with the simulation results, as well as the downhole gauge analysis.

Research on the connectivity of urban river network-wetland and water quality simulation.

The connectivity of urban river networks plays an important role in cities in many aspects, such as urban water safety, water quality (WQ), and aquatic ecological balance. This study focuses on the river network and the Majiawan Wetland in the Chaoyang District of Beijing by establishing a two-dimensional hydrological WQ model employing various water allocation schemes between the river network and the wetland. Water circulation and WQ are the main indexes, and the effects of different scenarios on improving water circulation and WQ are simulated and compared. This study demonstrates that the addition of water replenishment at the intersection of river network and internal slow-water zones of the wetland (Scheme 2) has greater effectiveness in improving both hydrology and WQ compared to two other schemes. The water area of the Majiawan Wetland has expanded, and water velocity has increased. Using chemical oxygen demand, total nitrogen, and total phosphorus as the index values for determining the water class, the WQ of about 20% of the wetland area was reached Water Class II (domestic drinking water), with Water Class III (general industrial water) accounting for the other 80%. This study provides valuable evaluation and reference for similar areas of urban river network connectivity.

Influence of Fluvial Discharges and Tides on the Salt Wedge Position of a Microtidal Estuary: Magdalena River

The linkage between the salt wedge, tidal patterns, and the Magdalena River discharge is established by assessing the ensuing parameters: stratification (ϵ), buoyancy frequency (β), potential energy anomaly (φ), Richardson number by layers (RL), and bottom turbulent energy production (P). The salinity, temperature, density, and water velocity data utilized were derived from MOHID 3D, a previously tailored and validated model for the Magdalena River estuary. To grasp the dynamics of the river, a flow regime analysis was conducted during both the wet and dry climatic seasons of the Colombian Caribbean. The utilization of this model aimed to delineate the estuary’s spatial reach, considering flow rates spanning from 2000 to 6500 m3/s across two tidal cycles. This approach facilitates the prediction of the position, stability, and stratification degree of the salt front. Among the conclusions drawn, it is highlighted that: 1. The river flow serves as the principal conditioning agent for the system, inducing a strong estuary response to weather stations; 2. The extent of wedge intrusion and the river discharge exhibit a non-linear, inversely correlation; 3. Tidal waves cause differences of up to 1000 m in the horizontal extent of the wedge; 4. Widespread channel erosion occurs during the rainy season when the salt intrusion does not exceed 2 km; 5. Flocculation processes intensify during the transition between the dry and wet seasons; 6. The stability of the salt layering and the consolidation of the FSI–TMZ are contingent upon the geometric attributes of the channel.

CFD-Based Study on the Flow and Kinetic Energy Characteristics of a Supercritical Suspended Abrasive Water Jet in the Deep-Sea Environment

A supercritical suspended abrasive water jet with dual inputs of pressure and heat is proposed to improve the cutting performance of the conventional suspended abrasive water jet in deep-sea environments. The paper studies the flow and kinetic characteristics of the supercritical suspended abrasive water jet. The CFD simulation method is proposed to investigate these characteristics by integrating a programmed database of supercritical water material properties with Ansys Fluent. The simulation and comparison show that abrasive particle density, abrasive particle size, inlet pressure, and water temperature affect the acceleration process of the abrasive particles. At the nozzle outlet, the velocity of the abrasive particles reaches over 95% of the supercritical water velocity. With the proposed supercritical abrasive water jet, the jet velocity is increased by 192.2% to 402.40 m/s compared to the conventional suspended abrasive water jet, reducing the amount of water used by 67.7% at a specified temperature of 773.15 K. Correspondingly, the medium kinetic energy is increased by 177.7% and the medium kinetic energy ratio is 2.78. The particle kinetic energy is increased by 723.2% and the particle kinetic energy ratio is 8.23.

Study on the effect law of jet angle on the cooling of hot-rolled L-beam

The uniformity of cooling affects the organizational properties and product quality of the L-beam. Problems such as bending deformation of the L-beam and excessive residual stresses inside the finished product are mainly caused by uneven cooling. The jet angle is an important cooling parameter in the cooling process of L-beam. In this study, the flow field and cooling law during jet cooling of hot-rolled L-beams were investigated by means of numerical simulation using the jet angle as a variable. The jet angle is −45°∼30° on the lower surface of the short edge of the L-beam due to space limitation, and the jet angle is −45°∼45° on the rest of the parts, and the other process parameters are kept unchanged. The velocity distribution, pressure, water flow, and temperature distribution on the cooling surface and the average heat transfer coefficient were analyzed. The results show that the jet angle has a significant effect on the cooling of each part of the L-beam. With the increase of the jet angle, the asymmetry of water velocity, pressure distribution, water flow distribution, and temperature distribution on the surface of the cooling surface increased significantly. The distribution of heat flux corresponds well to the distribution of temperature. As the jet angle increases the surface average heat transfer coefficient gradually decreases, and the maximum average heat transfer coefficient appears in the vertical jet. Gravity will also have a certain effect on the cooling of the L-beam.

Waterfront developments and engineered canals in the UAE

Engineered canals and waterfront developments as a means to revitalize aging riverfront and coastal areas, dominated until the mid-thirties by industrial buildings and warehouses, have been at the forefront of many American and European cities. Urban revitalization is accomplished after prolonged public participation and has succeeded to transform abandoned areas to healthy public spaces, renovating old warehouses and industrial buildings to apartments with water views, and keeping alive the historical memory of a city. In contrast, in the United Arab Emirates (UAE), most of these waterfront developments, such as Al-Qana, a recent project in Abu Dhabi promote forms of modern, spectacular architecture that project a sense of departure from tradition, local culture and architecture. This is also visible in the area around the Dubai canal, which has opted for a modern development on its banks, replacing parts of an existing open park. A project that diverges from such an approach is the two-decades old waterfront project in the city of Sharjah, UAE. Al-Qasba in Sharjah aimed for a more balanced approach, intertwining new architectural forms with hybridized Islamic ornaments. The current article analyzes these three UAE waterfront development projects, focusing on the one in Abu Dhabi. In order to assess the water quality in these engineered canals on the long term we created simulation waterflow models using 2D Finite Element Surface Water Modelling System (FESWMS). Our hydrodynamic modeling results indicate that water velocities in some canals was better than others. Furthermore, on the long-term Al-Qana may require mechanical means in order to maintain healthy waterflow conditions.

A Numerical Study of the Effect of Water Speed on the Melting Process of Phase Change Materials Inside a Vertical Cylindrical Container

The present work offers a thorough analysis of the impact of water velocity on phase change material (PCM) melting in a vertical cylindrical container. A detailed quantitative analysis uses sophisticated numerical techniques, namely the ANSYS/FLUENT 16 program, to clarify the complex relationship between enthalpy and porosity during the melting process. The experimental focus is on phase transition materials based on paraffin wax, particularly Rubitherm RT42. This study’s primary goal is to evaluate the effects of different water velocities (that is, at velocities of 0.01 m/s, 0.1 m/s, and 1 m/s) on the PCM’s melting behavior at a constant temperature of 333 K. This work intends to make a substantial contribution to the development of thermal energy storage systems by investigating new perspectives on PCM behavior under various flow circumstances. The study’s key findings highlight the possible ramifications for improving PCM-based thermal energy storage devices by revealing significant differences in melting rates and behavior that correlate to changes in water velocities. Future research is recommended to explore the impact of temperature variations, container geometries, and experimental validation to improve the accuracy and practicality of the results and to advance the creation of sustainable and effective energy storage solutions.

Dynamics of River Flood Waves below Hydropower Dams and Their Relation to Natural Floods

The dynamic behavior of flood waves on rivers is essential to flood prediction. Natural flood waves are complex due to tributary inputs, rainfall variations, and overbank flows, so this study examines hydropower dam releases, which are simpler to analyze because channel effects are isolated. Successive arrival times and heights of peaks along 9 rivers with multiple stream gauges downstream of hydroelectric dams show that flow peaks typically become exponentially lower and wider with distance. The propagation velocity of peaks increases with water depth and channel slope but decreases with downstream distance and greater channel tortuosity. A rich hierarchy of velocities was found. Hydropower pulses progress at or in slight excess of the theoretical celerity, which is faster than the propagation rate of average natural floods, which in turn exceeds the mean velocity of water in the channel, yet the water moves faster than the peaks of record floods. The progressive changes to the height, shape, and velocity of hydropower flow peaks are simulated by the first analytical solution to the convolution integral for a rectangular source pulse that is based on diffusion-advection theory. Available data support some widely held expectations while refuting others. An expanded definition of “water mining” is proposed.

Projected changes in extreme daily precipitation linked to changes in precipitable water and vertical velocity in CMIP6 models

Understanding the drivers of precipitation and their changes in a non-stationary climate is crucial for effective climate adaptation and water resource management, as it helps us anticipate and respond to shifting precipitation patterns and their impacts. Here, analysing simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) we show that the conditional probability of extreme daily precipitation given joint extremes of two drivers (precipitable water and vertical velocity) will be stable in a 3 °C warmer future. Consistent with earlier work, we find that the near-global increase in precipitable water (thermodynamic influence) is the baseline for changes in extreme precipitation, which are modulated by changes in vertical velocity (dynamic influence). Thus, in regions where vertical velocity increases, the effect of the two drivers is additive and their changes contribute to an increase in extreme precipitation. The changes of the two drivers are opposite where vertical velocity decreases, resulting in only small increases in extreme precipitation or even a decrease. Furthermore, we reveal that there are moderate changes in the dependence between the drivers, which are larger over the ocean than over landmasses, but they contribute only little to the overall changes in extreme precipitation. We conclude that the use of two very simple drivers that are readily available from climate models can be of great utility for evaluating precipitation extremes in models and understanding their projected changes.

Spatio-temporal characterisation of local scour around a circular bridge pier in cohesive soil with different clay/silt ratio

This paper presents new data on scour around a vertical pier in cohesive soils. It specifically focuses on the temporal evolution of local scour hole around the pier with increasing the clay/silt ratio content. Series of flume tests were performed using soil mixtures made with 85% fine sand and 15% fines. The fines fraction used in the soil mixtures includes silt, kaolinite clay, and various combinations of both with different proportions. The water velocity during the tests was kept constant and slightly above the erosion critical velocity of the fine sand used in the mixtures. A 3D laser scanner was employed to continuously record the geometry of the scour hole. Results show that increasing the Kaolinite clay in the fine fraction reduces significantly the scour. The mixture with a range around 7.5–10% of kaolinite clay fines content provides the threshold composition for cohesive soil behaviour effect in scouring process, recognized through scour pattern change. As the clay content increases, notable reductions are observed in the dimensions of the scour hole. Furthermore, the temporal evolution of maximum scour depth measured in flume was in agreement with the results from SRICOS-EFA (Scour Rate in COhesive Soil - Erosion Function Apparatus) method.

The effect of planting grass filter strips on fishes in agricultural headwater streams

Abstract Grass filter strips (i.e., herbaceous riparian buffers) are a widely used conservation practice in the United States to mitigate the impacts of agriculture on streams and rivers. Yet, only a limited amount of information is available on the effects of grass filter strips on stream fishes and instream habitat conditions and long‐term assessments are rare. The objective of this research was to document the long‐term effects of planting grass filter strips adjacent to channelized agricultural headwater streams on fish community structure and instream habitat. Fishes, instream habitat and riparian characteristics were sampled from three channelized agricultural headwater streams without grass filter strips, three channelized agricultural headwater streams with grass filter strips and two unchannelized streams having forested riparian habitats in central Ohio from spring of 2006 to autumn of 2015. Fish species richness, abundance, darter species richness, per cent darters, sunfish species richness, minnow species richness and per cent headwater fishes did not differ among riparian habitat types. Darter species richness and per cent darters differed annually. Mean water depth, velocity, wetted width, instream habitat diversity, dominant grain size and per cent instream wood did not differ among riparian habitat types. Mean water depth, water velocity, wetted width and instream habitat diversity exhibited annual differences. Additionally, mean riparian width, woody vegetation density and per cent canopy cover were greater in forested streams than the unplanted and grass filter strip streams. Riparian characteristics did not differ annually. The lack of fish community responses 10–13 years after planting grass filter strips is probably due to the lack of corresponding changes in hydrological characteristics, substrate and instream wood amounts. These results suggest that grass filter strips should not be implemented alone but in conjunction with conservation practices that will improve physical habitat quality and water quality.

ASSESSING LOCAL PORE WATER VELOCITY ALONG PREFERENTIAL FLOW IN EARTHEN DAM USING SALT TRACER

The local pore water velocity along the preferential flow path signifies the hydraulic parameter responsible for erosion within an earthen dam. This study introduces an empirical approach to ascertain the local pore water velocity within the earth dam's leakage zones by monitoring the travel time of the salt tracer through the corresponding electric potential anomalies in the ground. The alignment of electric potential anomalies with the movement of the salt tracer plume over time was confirmed through experiments on a physical model coupled with numerical simulations. The pore water velocity, calculated based on the location of the maximum electric potential anomaly, demonstrated excellent agreement with the experimental value, with an error of under 6%. For illustrative purposes, a field-scale salt tracer test was conducted at a leaking earthen dam in Vietnam. The tracer breakthrough curve originating from the leakage point revealed that the seepage water's travel time is approximately 40 days. The results of electric potential anomalies over time indicate that the pathway of seepage flow from upstream to the leakage point forms a horizontal V-shape, with the local pore water velocity ranging from 1.7 to 9.9x10-5 m/s. These local pore water velocities are subsequently compared with the critical seepage velocity to assess in-situ information regarding the internal erosion status of the target dam.

Droplet motion in a microchannel: The influence of electrokinetic effects at liquid-liquid interfaces

The electrokinetic effects at fluid interfaces can be utilized for droplet manipulation and separation in water, showing promising applications in areas such as oil-water separation and liquid-liquid extraction. In this study, numerical simulations are employed to investigate the impact of electrokinetic effects at the droplet surface and the horizontal interface between a non-conductive liquid and water on the electrokinetic velocity of a droplet within a microchannel. The findings indicate that as the magnitude of the negative zeta potential intensifies at the horizontal liquid-liquid interface, the flow velocity of non-conductive liquid gradually decreases and reverses direction when the zeta potential of the interface exceeds that of the channel wall. Conversely, the flow velocity of water continues to rise, resulting in an increased droplet movement velocity in water. The study also reveals that a lower water height and a greater non-conductive liquid height lead to faster water flow velocity and, consequently, a swifter droplet movement velocity. Additionally, the dynamic viscosity of the droplet has minimal impact on its electrokinetic velocity.

Effects of exercise training on the external morphology, growth performance, swimming ability, body composition and metabolism of juvenile black seabream Acanthopagrus schlegelii

Multiple studies have shown that exposure to moderate water currents (exercise training) can improve growth and physiological performance of hatchery-reared fish. Proactive implementation of sustained aerobic swimming training can be particularly beneficial for improving post-release performance of fish in stock enhancement- or ‘ranching’ programs. Black seabream Acanthopagrus schlegelii is an important species in aquaculture and stock enhancement in the East China Sea. For juveniles of this species, we assess the impacts of exercise training at various flow rates on the morphology, growth performance, swimming ability, body composition and locomotors metabolism. A group of sibling juvenile fish (initial mass: 13.72 ± 0.29 g) underwent daily exercise training for 12 h (9:00–21:00) over 30 days at four different water velocities (0, 1, 2, or 4 body lengths per second, BL/s). All the trained fish exhibited a significant decrease in their respiratory metabolic rate during the test of swimming ability. Fish from the 2 BL/s training group exhibited a significantly increased burst swimming speed compared to the other groups. Fish from 1 BL/s training group showed elevated hexokinase activities in the white muscle and citrate synthase activities in the liver compared to the 0 BL/s group. Citrate synthase activities in the white muscle of fish from the 2 BL/s training group were elevated, along with citrate synthase activities in the liver, as compared to 0 BL/s. The fish in the 4 BL/s training group showed a tendency for increased crude protein content and a corresponding decrease in crude lipid content. Morphological analysis revealed that fish in the 4 BL/s group exhibited larger dorsal fins and more streamlined body profiles, compared to 0 BL/s. Activities of white muscle citrate synthase as well as liver hexokinase activity were higher in the 4 BL/s group, while lactate content activity in the white muscle were lower compared to 0 BL/s. These findings underscore the effectiveness of training at 2 BL/s, offering a promising strategy to enhance the performance of juvenile black seabream for stocking initiatives.