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This study conducted an in-depth analysis of the sediment dynamics in the lower reaches of the Changhua River and its estuary on Hainan Island. Through field collection of topographic data and sediment sampling, combined with advanced computational techniques, the study explored the transport pathways and depositional patterns of sediments. The grain size trend analysis (GSTA) method was utilized, in conjunction with the Flemming triangle diagram method, to classify the dynamic environment of the sediments. Furthermore, hydrodynamic modeling results were integrated to further analyze the transport trends of the sediments. The study revealed that the sediment types in the research area are complex, primarily consisting of gravelly sand and sandy gravel, indicating a generally coarse sedimentary environment in the region. The sediments in the lower reaches of the Changhua River generally transport towards the south and southwest (in the direction of Beili Bay). The net sediment transport directions inferred from the GSTA model are largely consistent with the Eulerian residual flow patterns, especially in the offshore area, where discrepancies are observed in the nearshore zone. The nearshore transport is influenced by the combined effects of alongshore currents, residual flows, and river inputs, while the offshore transport exhibits a shift from the northwest to southwest directions, reflecting the regional circulation patterns. [ABSTRACT FROM AUTHOR]

A comprehensive modeling framework utilizing hydrodynamic and sediment transport models (MIKE Hydro River, MIKE 21 FM, MIKE 21C) was applied to the 33.57 km stretch of the Banshadhara River from Banshadhara bridge, Gunupur to Kashinagar town. Daily discharge, water levels, and sediment data from 2013 to 2022 of Gunupur and Kashinagar gauge stations was used as model input, and calibration–validation of models. Additionally, satellite remote sensing data used for determined Manning's roughness (n) values as well compared the model outputs. Calibration procedures ensured high accuracy, with MIKE Hydro River achieving 98.3% agreement between observed and simulated water levels. 1D sediment transport model showing significant variability in total bed load values ranging from 0.3 to 3.83 m^3/s. The Wilcock & Crowe gravel bed load formula accurately predicted bed load transport within the expected magnitude, albeit tending to overestimate transport, indicative of supply-limited conditions. 2D MIKE 21 FM simulations highlighted flow dynamics, with rapid flood arrival at Kashinagar and varying current speeds along the river, especially at bends. MIKE 21C, focused on the central portion, indicated erosion processes at river bends with high discharge. Sediment transport model accuracy was approximately 86.7%, capturing general trends despite occasional discrepancies. Over a 10-year simulation, erosion trends and potential river course shifting were observed, particularly near bends. The analysis provides valuable insights for river management, flood risk mitigation, water resource management, infrastructure planning, and environmental preservation in the Banshadhara River basin and similar environments. Article Highlights: Accurate modeling predicts river erosion and possible course shifts, vital for flood risk planning. Sediment transport varies widely, indicating complex riverbed dynamics impacting river management. Study offers insights into managing river ecosystems, infrastructure, and environmental preservation. [ABSTRACT FROM AUTHOR]

Copyright of South China Fisheries Science is the property of South China Fisheries Science Editorial Department 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.)

This article presents the results of an experimental study of the coolant flow in a fuel rod bundle of a nuclear reactor fuel assembly of a small modular reactor for a small ground-based nuclear power plant. The aim of the work is to experimentally determine the hydrodynamic characteristics of the coolant flow in a fuel rod bundle of a fuel assembly. For this purpose, experimental studies were conducted in an aerodynamic model that included simulators of fuel elements, burnable absorber rods, spacer grids, a central displacer, and stiffening corners. During the experiments, the water coolant flow was modeled using airflow based on the theory of hydrodynamic similarity. The studies were conducted using the pneumometric method and the contrast agent injection method. The flow structure was visualized by contour plots of axial and tangential velocity, as well as the distribution of the contrast agent. During the experiments, the features of the axial flow were identified, and the structure of the cross-flows of the coolant was determined. The database obtained during the experiments can be used to validate CFD programs, refine the methods of thermal-hydraulic calculation of nuclear reactor cores, and also to justify the design of fuel assemblies. [ABSTRACT FROM AUTHOR]

The study focuses on enhancing the performance of fluidized bed systems, which are widely used in industrial processes requiring efficient heat and mass transfer. By integrating ribs at angles of 135, 150, and 165° on the riser wall, the research assesses their impact on hydrodynamic behavior and heat transfer using CFD simulations. The simulations, confirmed through experimental data, revealed that the 150° ribbed model outperforms others by improving particle mixing and achieving the highest heat transfer coefficient. The investigation also covered static pressure, solid volume fraction, and particle velocities at different bed heights (30, 60, 90, and 120 mm), showing that ribbed models significantly enhance turbulence and particle distribution, with the 150° ribs providing a balance between dynamic mixing and stable flow. [ABSTRACT FROM AUTHOR]

To adapt to the change of aquaculture workshop site, optimize the shape of aquaculture tanks and improve the utilization rate of breeding space, it is necessary to determine the appropriate length-width ratio parameters of aquaculture tanks. In this paper, computational fluid dynamics (CFD) technology is adopted to study the flow field performance of aquaculture tanks with different L/B ratios (L: the length; B: the width, of aquaculture tank) and different jet direction conditions (lengthways jet and widthways jet). A three-dimensional numerical calculation model of turbulence in rounded rectangle aquaculture tanks in dual-diagonal-inlet layout was established. Jet directions are arranged lengthways and widthways, and the water flow velocity, resistance coefficient change, vorticity, etc. are analyzed under two working conditions. Results show that the flow field performance in aquaculture tank decreases with the increase of the L/B ratio. The flow field performed well when L/B was 1.0–1.3, sharply dropped at 1.4–1.6, and poor at 1.7–1.9. The results provided a theoretical basis for the design and optimization in flow field performance of the industrialized circulating aquaculture tanks. [ABSTRACT FROM AUTHOR]

Abstract A comprehensive modeling framework utilizing hydrodynamic and sediment transport models (MIKE Hydro River, MIKE 21 FM, MIKE 21C) was applied to the 33.57 km stretch of the Banshadhara River from Banshadhara bridge, Gunupur to Kashinagar town. Daily discharge, water levels, and sediment data from 2013 to 2022 of Gunupur and Kashinagar gauge stations was used as model input, and calibration–validation of models. Additionally, satellite remote sensing data used for determined Manning’s roughness (n) values as well compared the model outputs. Calibration procedures ensured high accuracy, with MIKE Hydro River achieving 98.3% agreement between observed and simulated water levels. 1D sediment transport model showing significant variability in total bed load values ranging from 0.3 to 3.83 m^3/s. The Wilcock & Crowe gravel bed load formula accurately predicted bed load transport within the expected magnitude, albeit tending to overestimate transport, indicative of supply-limited conditions. 2D MIKE 21 FM simulations highlighted flow dynamics, with rapid flood arrival at Kashinagar and varying current speeds along the river, especially at bends. MIKE 21C, focused on the central portion, indicated erosion processes at river bends with high discharge. Sediment transport model accuracy was approximately 86.7%, capturing general trends despite occasional discrepancies. Over a 10-year simulation, erosion trends and potential river course shifting were observed, particularly near bends. The analysis provides valuable insights for river management, flood risk mitigation, water resource management, infrastructure planning, and environmental preservation in the Banshadhara River basin and similar environments.

Global climate change increases storm frequency and Sea Level Rise (SLR). This leads to an increased risk of coastal flooding, reduced effectiveness of protective structures, and intensified coastal erosion and retreat. The Bona and Ceinturon beaches, two beautiful sandy beaches with low-lying topography along the eastern branch of the Giens double tombolo on the western coast of Hyères Bay, have high tourist value. These areas are very vulnerable to SLR, which is believed to reduce the effectiveness of the shore protection structures built on these sandy beaches. The effects of SLR on changes in the hydrodynamic characteristics of these water bodies need to be quantified. This may help clarify the relationship between SLR and coastal erosion. This study investigated the variation of wave height and current speed due to SLR at the Bona and Ceinturon beaches using a coupled numerical model. The performance of this model was calibrated by comparing the model results with the in situ measured data. The research results are the basis for assessing the impact of SLR due to climate change on this area and provide a useful solution for coastal management in the future.

Tensegrity robotic fish is an emerging solution in the field of robotic fish, and its dynamic model plays a crucial role in guiding the improvement of swimming performance. However, there is a lack of in-depth research in this area. This paper proposes a planar dynamic model for the tensegrity robotic fish, which can be used to simulate and investigate the influence of body stiffness on swimming performance. An equivalent modeling approach is introduced for the soft fish skin and tail fin to consider their effects of flexibility on the robotic fish's swimming motion. A hydrodynamic discretization model based on virtual nodes is proposed to incorporate hydrodynamic effects such as drag force, lift force, and added mass into the fish's vertebral column. By integrating the above models, the dynamic model for the tensegrity robotic fish is established after embedding the tail joint constraints. The method of reconstructing fish body waves in the simulation is provided to calculate fish swimming characteristics. The parameter identification method for the drag coefficient and torque coefficient is proposed. The dynamic model of the tensegrity robotic fish is verified using swimming experimental data. By conducting numerous numerical simulations, the effects of the body stiffness distribution, tail fin stiffness, and fish skin stiffness on the swimming performance are analyzed. The simulation results reveal the significant role of adjusting body stiffness in enhancing the swimming characteristics of the robotic fish. [ABSTRACT FROM AUTHOR]

Karst aquifers play a fundamental role in the water supply of northwest Tunisia, especially in the Teboursouk region. Due to their specific hydrogeological properties, these aquifers are difficult to exploit due to their complex and heterogeneous structures. To better understand karst aquifers, different research methods are used to study the karst groundwater system in Aïn Kebrit Karst spring. It is thermal warm water (20°C) of Teboursouk region (northwestern Tunisia). The study area is characterized by sub-humid to semi-arid climate expressed by elevated and irregular rainfall associated with complex geological and tectonic structures dominated by Triassic outcrops "diapir zone" in the study area Karst system is an essential and even unique water resource. The present work attempts to investigate the geological, hydrogeological, hydro-chemical and isotopic data of Aïn Kebrit Karst spring water. The results will help in the identification of the main process and factors controlling groundwater mineralization. The water quality is dominant by Ca–Mg–Cl–SO4. The Total Dissolved Solids (TDS) values varied between 10 and 14.4 g L–1. The hydrochemistry of this water was linked with carbonate weathering and evaporates dissolution of Triassic outcrops. The results obtained by the different types of isotopic analyzes (δ18O = −5.8‰ V-SMOW and δ2H = −34‰ V-SMOW) show that it is a mix of old water (deep warm water) and recent water (cold superficial and meteoric). [ABSTRACT FROM AUTHOR]

Since the 1980s, the robust economic growth of China has prompted extensive land reclamation projects along its coastline, notably affecting local hydrodynamics and resulting in ecological repercussions. Using a nearshore finite volume ocean model, we constructed a hydrodynamic model for Shacheng Bay, a southeastern coastal region with a winding and narrow entrance. We examined the hydrodynamic changes and mangrove dynamics over the past 36 years and the relationship between hydrodynamic alterations and mangrove degradation. Simulation results reveal that extensive reclamation projects between 1984 and 2000 weakened the current in Shacheng Bay, leading to decreased water exchange capacity and a significant reduction in mangrove area from 0.3 to 0.06 km2. During this period, over 37% of mangrove degradation was ascribed to time-changing hydrodynamic variables without the direct influence of land reclamation. The results also highlight the changes in local hydrodynamics and water exchange patterns that adversely influenced mangrove growth. From 2000 to 2020, there were minimal coastline changes in Shacheng Bay, demonstrating reduced land reclamation activities. This stopped the further weakening trend of the currents, with a slight increase during ebb tides, while the residual current continued to weaken due to the decreasing tidal prism and water exchange capacity. The mangrove area partially recovered during this period, expanding from 0.06 to 0.11 km2, predominantly in new areas instead of where mangroves disappeared from 1984 to 2000. This work underlines the intricate relationship between land reclamation, hydrodynamics, and mangrove ecosystems, underscoring the need for sustainable coastal development strategies. [ABSTRACT FROM AUTHOR]

Abstract Dissolved air flotation (DAF) is an effective method for separating suspended oil and solid particles from wastewater by utilizing small air bubbles. This study aims to investigate the impact of key factors, such as saturating pressure and water flow rate, on the separation of fine oil droplets from a water stream. The macroscopic flow patterns within the cell were analyzed using particle image velocimetry (PIV), while Digital Image Analysis (DIA) was employed to study microscopic phenomena, including oil droplet rising velocity and oil-bubble contact mechanisms. Our findings propose a safe operating window (specifically, water flow rate and saturation pressure) for the effective separation of oil droplets without any oil escaping into the clean water stream. It was found that the oil droplet rising velocity increases with the saturation pressure up to 200 kPa. However, a further increase in the pressure of the air saturating chamber leads to a decrease in oil droplet rising velocity. Additionally, we identified a peak in rising velocity at an oil droplet size of approximately 200 µm. Below this threshold, the rising velocity increases with droplet size, while for droplet sizes exceeding 200 µm, the rising velocity decreases with size. This behavior can be explained by the conflicting effects of droplet size increment according to the Stokes law for the rising velocity of oil droplets. As the droplet size increases, the average density of the bubbles/droplet aggregate rises, reducing the ∆ρ in the Stokes law and subsequently lowering the aggregate rising rate. However, as per the Stokes law, the oil droplet rising velocity increases proportionally to the square of its size.

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management 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.)

Despite the continued rise in popularity of powered catamarans for recreational and commercial applications, there is limited published research on the factors that improve or reduce a powered catamaran's hydrodynamic stability. There is no definitive research on a catamaran's hydrodynamic stability during a turn, and current regulations to control the risks are proving ineffective for modern speeds and power. Research on the hydrodynamic stability of catamarans was conducted using a custom-built vessel and its multi-sensor data logger. Test results confirmed serious concerns for safety regulation and acceptance testing of powered catamarans for hydrodynamic stability. The experiments have produced new insights as to why powered catamarans are at risk of capsizing and created a baseline for future testing. The work reported in this article provides an original characterisation of the multi-factor relationships that impact the instability of a powered planing catamaran. The results provide a starting point for the creation of a predictive model and approach to improve catamaran design and safety. [ABSTRACT FROM AUTHOR]

Microplastics in the environment are considered complex pollutants as they are chemical and corrosive-resistant, non-biodegradable and ubiquitous. These microplastics may act as vectors for the dissemination of other pollutants and the transmission of microorganisms into the water environment. The currently available literature reviews focus on analysing the occurrence, environmental effects and methods of microplastic detection, however lacking a wide-scale systematic review and classification of the mathematical microplastic modelling applications. Thus, the current review provides a global overview of the modelling methodologies used for microplastic transport and fate in water environments. This review consolidates, classifies and analyses the methods, model inputs and results of 61 microplastic modelling studies in the last decade (2012–2022). It thoroughly discusses their strengths, weaknesses and common gaps in their modelling framework. Five main modelling types were classified as follows: hydrodynamic, process-based, statistical, mass-balance and machine learning models. Further, categorisations based on the water environments, location and published year of these applications were also adopted. It is concluded that addressed modelling types resulted in relatively reliable outcomes, yet each modelling framework has its strengths and weaknesses. However, common issues were found such as inputs being unrealistically assumed, especially biological processes, and the lack of sufficient field data for model calibration and validation. For future research, it is recommended to incorporate macroplastics' degradation rates, particles of different shapes and sizes and vertical mixing due to biofouling and turbulent conditions and also more experimental data to obtain precise model inputs and standardised sampling methods for surface and column waters. [ABSTRACT FROM AUTHOR]

Dissolved air flotation (DAF) is an effective method for separating suspended oil and solid particles from wastewater by utilizing small air bubbles. This study aims to investigate the impact of key factors, such as saturating pressure and water flow rate, on the separation of fine oil droplets from a water stream. The macroscopic flow patterns within the cell were analyzed using particle image velocimetry (PIV), while Digital Image Analysis (DIA) was employed to study microscopic phenomena, including oil droplet rising velocity and oil-bubble contact mechanisms. Our findings propose a safe operating window (specifically, water flow rate and saturation pressure) for the effective separation of oil droplets without any oil escaping into the clean water stream. It was found that the oil droplet rising velocity increases with the saturation pressure up to 200 kPa. However, a further increase in the pressure of the air saturating chamber leads to a decrease in oil droplet rising velocity. Additionally, we identified a peak in rising velocity at an oil droplet size of approximately 200 µm. Below this threshold, the rising velocity increases with droplet size, while for droplet sizes exceeding 200 µm, the rising velocity decreases with size. This behavior can be explained by the conflicting effects of droplet size increment according to the Stokes law for the rising velocity of oil droplets. As the droplet size increases, the average density of the bubbles/droplet aggregate rises, reducing the ∆ρ in the Stokes law and subsequently lowering the aggregate rising rate. However, as per the Stokes law, the oil droplet rising velocity increases proportionally to the square of its size. [ABSTRACT FROM AUTHOR]

The propulsion system is the core component of unmanned underwater vehicles. The flapping propulsion method of marine animals' flippers, which allows for flexibility, low noise, and high energy utilization at low speeds, can provide a new perspective for the development of new propulsion technology. In this study, a new experimental flapping propulsion apparatus that can be installed in both directions has been constructed. The guide rail slider mechanism can achieve the retention of force in the direction of movement, thereby decoupling thrust, lift, and torque. Subsequently, the motion parameters of frequency–amplitude related to the thrust and lift of a bionic flapping-foil are scrutinized. A response surface connecting propulsion efficiency and these motion parameters is formulated. The highest efficiency of the flapping-foil propulsion is achieved at a frequency of 2 Hz and an amplitude of 40°. Furthermore, the impact of the installation mode and the aspect ratio of the flapping-foil is examined. The reverse installation of the swing yields a higher thrust than the forward swing. As the chord length remains constant and the span length increases, the propulsive efficiency gradually improves. When the chord length is extended to a certain degree, the propulsion efficiency exhibits a parabolic pattern, increasing initially and then diminishing. This investigation offers a novel perspective for the bionic design within the domain of underwater propulsion. This research provides valuable theoretical guidance for bionic design in the underwater propulsion field. [ABSTRACT FROM AUTHOR]

The present work investigates a comparative study between mechanical and ImhoflotTM cells on a mini-pilot scale and the applicability of one self-aspirated H-16 cell (hybrid ImhoflotTM cell) on an industrial scale on-site. The VM-04 cell (vertical feed to the separator vessel with 400 mm diameter) was fabricated, developed, and examined. The copper flotation experiments were conducted under similar volumetric conditions for both the ImhoflotTM and mechanical flotation cells keeping the rest of the parameters constant. Further, one H-16 cell was positioned at four different stages in the Gökirmak copper flotation circuit of the Acacia (Türkiye) copper beneficiation plant, i.e., at (i) pre-rougher flotation, (ii) rougher concentrate, (iii) cleaner-scavenger tailing, and (iv) first cleaning concentrate aiming at enhancing the flotation circuit capacity through flash flotation in the rougher stage, reducing copper grade in the final tailing, and increasing cleaning throughput, respectively. Comparative copper flotation tests showed that ultimate recoveries using the ImhoflotTM and mechanically agitated conventional cells were 94% and 74%, respectively. The industrial scale test results indicated that locating one pneumatic H-16 cell with the duty of pre-floating (also known as flash flotation) led to the enrichment ratio and recovery of 4.84 and 89%, respectively. Positioning the H-16 cell at the cleaner-scavenger tailings could diminish the copper tailings grade from 0.43% to 0.31%. Further, a relatively greater enrichment ratio and copper recovery were obtained using only one ImhoflotTM cell (1.76 and 64%) in comparison with employing four existing mechanical cells (50 m3, each cell) in series (1.45 and 60%) at the first cleaner stage. [ABSTRACT FROM AUTHOR]

Coastal zones are highly dynamic and constantly influenced by geomorphological and physical properties. Thus, estimating coastal vulnerability around the world is necessary for coastal zone management. Makran region, in the southeast of Iran, with a 133 km coastline, is considered a case study for vulnerability analysis and estimating its potential for further economic developments. The coastal vulnerability index (CVI) was considered with five parameters: geomorphology, regional elevation, coastal slope, shoreline changes and mean significant wave height. Significant wave height is an additional variable we added to CVI estimation compared to previous works. MIKE 21 software was used to extract this variable. Seven images from the Landsat satellite were employed to provide shoreline transformation. According to our results 52% of the coastline is ranked as high-vulnerability index, and 15% as very-high vulnerability index. We detected some anthropogenic areas with considerable accretion along the shoreline, while these areas were not considered vulnerable areas according to CVI. Thus, we reckon a sort of shortcoming in calculating CVI for not giving weight to the variables involved. This aim to be achieved necessitates organized historical research over the area, which was out of the scope of this sole research. Research highlights: Inclusive employment of geomorphic and hydrodynamic parameters is suggested for calculating CVI. However, a shortcoming in this calculation is the lack of information to give weight to the variables involved. More than half of Makran shoreline (67%) is ranked as high to very high-vulnerable area, which means specific concern is needed for any further anthropogenic activities around this area. Accretion can be counted as an issue on CZM, specifically on the area with anthropogenic activities, such as ports. [ABSTRACT FROM AUTHOR]

The use of tag devices in marine environments has become indispensable in attaining a better understanding of marine life and contributing to conservation efforts. However, the successful deployment and operation of underwater tags both depend significantly on their hydrodynamic characteristics, particularly their resistance to motion and stability in various environmental conditions. Herein, a comprehensive study on the hydrodynamic characteristics and optimization of an underwater tag designed for monitoring blue sharks is presented. Firstly, a validation process is conducted by comparing the computational fluid dynamics (CFD) results with the experimental data from Myring's study, focusing on the resistance characteristics of the tag's body and the impact of various operational conditions. Subsequently, the validated CFD model is applied to assess the hydrodynamic performance of the tag under different flow conditions, velocities, and angles of attack. Through iterative simulations, including mesh independence studies and boundary condition adjustments, the study identifies key parameters influencing the tag's resistance and stability. Furthermore, the paper proposes and implements design modifications, including the incorporation of stabilizing fins, aimed at minimizing resistance and improving the tag's equilibrium position. The effectiveness of these design enhancements is demonstrated through a comparative analysis of resistance and pitching moments for both preliminary and optimized tag configurations. Overall, the study provides valuable insights into the hydrodynamic behavior of underwater tags and offers practical recommendations for optimizing their design to minimize interference with the movement of tagged marine animals. [ABSTRACT FROM AUTHOR]

Makhool Dam is a proposed structure on the Tigris River in the Salah al-Din Governorate, northwest of Baiji. The reservoir's sediment sources encompass the Tigris River, the Greater Zab River, and the Lesser Zab River. Climate change exerts a significant influence on both sediment accumulation within the dam reservoir and associated water resources. This paper specifically investigates the impact of climate change on sediment dynamics within the Makhool Dam reservoir. HEC-RAS 6.3.1 has been used to simulate the sediment dynamics and flow for the three rivers entering the reservoir. The SSP2-4.5 and SSP5-8.5 emission scenarios were applied to the 2021-2040, 2041-2060, 2061-2080, and 2081-2100 of 2021–2100. The calibration process of the model was performed using recorded water surface elevation measurements. The model was validated using the sediment concentrations at the proposed Makhool Dam. The sediment mass decreases along the rivers from upstream to downstream. The sediment mass is anticipated to decrease by approximately 20% and 35% from 2021 to 2100 under the SSP2-4.5 and SSP5-8.5 scenarios, respectively. For the studied future period, the estimated annual sediment deposition under the SSP2-4.5 and SSP5-8.5 scenarios is around 22×106 tons and 19×106 tons, respectively. In addition, under these scenarios, the potential life of the Makhool Reservoir is expected to be 95.7 and 109.5 years, respectively. The findings of this paper can play a vital role in supporting planners and decision-makers in performing efficient strategies for climate change adaptation and mitigating the impact of climate change.

The new navigation channel for large vessels entering the Hau River through the Kenh Tat and Quan Chanh Bo channels was announced in January 2016. The navigation channel route through Dinh An estuary in Soc Trang province to Can Tho port was not deeply concerned by the agency because of the sedimentation phenomenon, which was very serious and complicated. Only small vessels of 1,000-2,000 DWT can pass through the Dinh An estuary navigation channel, whereas large vessels pass through the Kenh Tat and Quan Chanh Bo channels. However, the new navigation channel entering the Hau River is also seriously sedimented, especially in the Cua Dai An area, where the tributary route starts from the Hau River through the Quan Chanh Bo channel and the estuary area in the Duyen Hai harbor basin. These are two important bottlenecks that drastically reduce the throughput capacity of this new navigation channel. This paper proposed five options for the spatial arrangement of works to stabilize and protect the channel through the Dinh An estuary. A MIKE 21 couple mode was used to simulate hydrodynamic and sediment transport in the study area, and the impact of these options on the characteristics, including water level, flow velocity, and bottom topographic change, was analyzed and evaluated. Based on these results, an optimal solution was suggested.

The formation and evolution mechanisms of coal mine water quality are intricate, significantly influenced by multiple processes such as hydrodynamics, hydrochemistry, and biodegradation. A comprehensive investigation and elucidation of the mechanisms is theoretically crucial for the prevention and remediation of coal mine water pollution. The hydrogeological prototype of a goaf in a coal mine in the Ordos Basin is choosen, and a laboratorial physical model and a coupled hydrodynamic-chemical-biodegradation (HCB) milti-field numerical model for the goaf are established, focusing the water level rises and biogeochemistry processes. The research results demonstrate the significance of multi-field coupling effects on mine water quality. The water level filling up results shows that the matrix-fracture dual-porosity model effectively matches the water level in the goaf with a simulation error of 9.9%, which is much more accurate than the theoretical and the single-porosity model predictions. The simulation results of the hydrochemical field are relatively consistent with the experiments, with relative errors of 3.0%, 21.0%, and 6.2% for \begin{document}${\mathrm{SO}}_4^{2-} $\end{document}, \begin{document}${\mathrm{HCO}}_3^- $\end{document}, and pH, respectively. Results from different time periods indicate that water-rock reactions and microbial activities are not significant during the water storage process. After the goaf is filled up, the hydrodynamics almost stagnate, but the hydrochemical and microbial fields are relatively active. The pyrite oxidation reactions in the No.2 and No.3 coal seams increase the concentration of \begin{document}${\mathrm{SO}}_4^{2-} $\end{document} by about 24.6%. In the later stage, the water environment in the goaf evolves into weakly acidic and anaerobic reducing conditions, and the microbial degradation becomes prominent, reducing the \begin{document}${\mathrm{SO}}_4^{2-} $\end{document} concentration from its peak by 6.1%. A certain “self-purification” ability of mine water in the goaf after closure has been confirmed. By adjusting the microbial metabolic rate constant, the proportion of \begin{document}${\mathrm{SO}}_4^{2-} $\end{document} degradation can be induced up to 61.6%. In actual engineering scenarios, this target can be achieved through some strategies such as supplementing enough dissolved carbon nutrient substance and artificially establishing a closed anaerobic environment. This study expands the multi-field coupling laboratorial experiments and numerical modeling techniques to the formation and evolution of water quality in coal mine water in a goaf, and the constructive conclusions can provide theoretical guidance for the prevention and remediation of coal mine water pollution.

Nature-based solutions (NbS) offer a promising path to enhance climate-resilient shorelines. For instance, the creation of mussel beds in subtidal sandy shore systems provides a versatile strategy for coastal management, reinforcing coastal defense and fostering biodiversity, ultimately strengthening the resilience and well-being of coastal communities. This study analysed the changes in seabed dynamics and surrounding benthic communities as a result of the formation of mussel beds (Mytilus edulis) using an aquaculture longline system. Therefore, a comprehensive monitoring approach at two sites characterized by distinct hydrodynamic conditions was applied over a three-year period. To assess the effects, a before/after control/impact design (BACI) was employed. Seabed dynamics were evaluated by observing mussel bed persistence, erosion/deposition, and sediment composition. The influence on the benthic community included assessments of community structure and biodiversity. Finally, the impact of mussels, hydrodynamic conditions, and their interactions on seabed dynamics and benthic communities was examined using linear mixed models (LMMs). Factors such as mussel presence, Lanice conchilega abundance, shell cover, and sediment composition played a role in shaping the distinct characteristics observed between two different sites: a site that lies at a location that is more sheltered from hydrodynamic conditions, and a second site that is exposed to higher current and wave conditions. The sheltered site exhibited higher species density, richness, biomass, and diversity compared to the exposed site. In relation to the mussel bed development, mussel patches were found at both sites (with higher occurrence at the sheltered site) in the 2nd and 3rd years (mainly in summer towards early winter). The influence of mussels on sediment deposition was noticeable at the sheltered site, albeit lacking statistical significance, suggesting their potential role in erosion/deposition mechanisms. Also, a higher proportion of very fine sand was observed in the mussel bed compared to the bare sand. However, due to the absence of higher-density permanent mussel beds and irregular sedimentation/erosion patterns throughout the study period, no significant effect of the mussel beds on the community structure or diversity was found. In order to achieve a sustained and dense mussel bed and maximize the potential impact of mussels in combating climate change (e.g., shore protection and biodiversity enrichment), additional measures to increase coastal resilience against harsh hydrodynamic conditions may be necessary.

In a treatment of the linear stability problem of flow near a plane stagnation point, Brattkus and Davis introduced what they called "generalized Görtler disturbances," which they recognized as being self-similar. In this work, by the introduction of Mellin transforms, these solutions within restrictions are shown to form the elements of an integral representation. Also, derived are suitable constraints on the secondary vorticity, i.e., the x-component, which buttresses the analyses of earlier authors. [ABSTRACT FROM AUTHOR]

The hydrodynamics of a conical spouted bed was simulated utilizing the Eulerian–Eulerian Two-Fluid Model (TFM) incorporating a kinetic theory of granular flows. The simulations were confirmed with experimental data. To accurately examine the pyrolysis process, the hydrodynamics of the solid bed as well as the heat transfer inside it were analysed separately by considering a precise synthetic model. The effects of gas velocity, particle size, bed length, and temperature were thoroughly investigated. The results indicated that the amount of relative standard deviation increases with an increase in the inlet velocity into the bed. This amount of deviation at the inlet velocity (0.6 m/s for tar and gas flow to its maximum value of 9.1 and 9.4) is not desirable in product production and should be modified so that the amount of gas flow increases and the tar produced reaches the minimum possible amount. Also, the graphs of the relative standard deviation in terms of temperature indicate that the increase in temperature from 730 to 950 K is associated with a relatively smaller fluctuation of the relative standard deviation so that at the temperature of 730 K, it is 7.2 % for tar and 6.4 % for gas flow, while at temperature of 950 K, it is 6.5 % for wire and 6.8 % for gas flow. Finally, the results determined that small-diameter particles have a more significant fountain height and also higher velocity in the spout section. [ABSTRACT FROM AUTHOR]

The modification of surface geometries to reduce friction is an omnipresent topic of research. In nature, different low-friction surfaces, such as fish skins, exist. To transfer this knowledge to technical applications, for example, to journal or plain bearings, many numerical and experimental studies of textured surfaces have been performed. In this work, the influence of the geometric parameters (texture length l , width b , angle α and start position x s t a r t) of a wedge-shaped texture on three different convergent oil film gaps was analyzed in full-film lubrication and compared with untextured oil film gaps. With the aid of a CFD (computational fluid dynamics) model, a comprehensive variation study was conducted, and the best-performing wedge-shaped texture was determined. The results show that an open texture at the inlet provides the largest improvement. Furthermore, it can be observed that the optimal relative texture width and absolute inlet height for the three investigated oil film gaps are similar. In contrast to the volume flow of the untextured geometry, the volume flow of the textured one is significantly higher, especially that perpendicular to the movement direction. [ABSTRACT FROM AUTHOR]

The National Capital Integrated Coastal Development (NCICD) program was prioritized as a disaster reduction technology within the annual target of BRIN in 2022. It is a part of the North Java Coastal Integrated Development Program project. A coastal reservoir development plan at the Cisadane River estuary is one of the outcomes. In this case, hydrodynamic modelling is needed to acquire hydrodynamic properties under the existing condition of Cisadane downstream, and it applied the Delft3D-FLOW model. The bathymetric data used in this simulation was obtained from the assimilation of national bathymetric data with a grid spacing of 180 m and field survey data with a horizontal resolution of 10 m and transect spacing of 200 m seaward of the Cisadane estuary. It has interpolated in a regular structured grid with 100 m and 50 m grid spacing. In addition, other data used are three hourly wind data downloaded from the European Centre for Medium-Range Weather Forecasts (ECMWF) and the daily discharge of the Cisadane River in 2021. Astronomical water level data generated from TPXO 7.2 and TPXO 8 were used in the boundary conditions. These data are simulated using the two and three-dimensional flow model Delft3DFLOW during November 1 - 15, 2021, using four manning coefficients (n) values, which are 0.03; 0.035; 0.04; and 0.045. The validation formulation used Normalization Root Mean Square Error (NRMSE), resulting in 5.3 - 9.6% for all the manning values and domains. The highest correlation coefficient of current velocity (u-v components) is acquired in the 10 km² domain with 0.797 for the L3 (bottom layer). [ABSTRACT FROM AUTHOR]

Objectives: To introduce a novel hydrodynamic design for a flexible ureteroscope that can increase stone debris clearance. Methods: Based on hydrodynamics, the new design allowed the ureteroscope to have six water jets. Fluid gushed from the six jets and would ultimately converge into an eddy. The safety and stone debris clearance efficiency were tested in a 3D-printed kidney model. Stone fragments between 0.5 and 1 mm were used to mimic the debris. A ureteroscope already approved for marketing was used as a control. Results: The new design did not change the local renal pressure and did not raise the whole renal pressure under irrigation at 80 or 100 mL/min but slightly raised it under irrigation at 120 mL/min. The pressures in the 2 g stone clearance procedures were 26.0, 33.1, and 37.5 cmH2O for the new design and 25.1, 30.2, and 39.3 cmH2O for the current design; in the 4 g stone clearance procedures, the pressures were 30.1, 37.2, and 40.0 cmH2O for the new design and 26.9, 30.8, and 39.8 cmH2O for the current design, all under conditions of 80, 100, and 120 mL/min irrigation, respectively. The new design significantly improved the stone clearance rate by ∼10-fold. It effectively cleared 2 and 4 g stones within 900 seconds under the three irrigation rates. In contrast, the current design cleared <10% of the stone debris in all tests. Conclusion: The new hydrodynamic design significantly improved the stone debris clearance rate without causing obviously increased renal pressure, and the improvement was maintained under different irrigation pressures and stone burdens. [ABSTRACT FROM AUTHOR]

Wakes produced by underwater vehicles, particularly submarines, in density-stratified fluids play a pivotal role across military, academic, and engineering domains. In comparison to homogeneous fluid environments, wakes in stratified flows exhibit distinctive phenomena, including upstream blocking, pancake eddies, internal waves, and variations in hydrodynamic performance. These phenomena are crucial for optimizing the operation of underwater vehicles. This review critically assesses the hydrodynamic and thermodynamic aspects of these wakes through an integration of theoretical, experimental, and numerical approaches. The hydrodynamic wake evolution, comprising near-wake, non-equilibrium, and quasi-two-dimensional regimes, is scrutinized. The underlying physics, encompassing energy transformation, vertical motion suppression, and momentum dissipation, are analyzed in detail. Special emphasis is placed on numerical methods, encompassing diverse approaches and turbulence models and highlighting their differences in fidelity and computational cost. Numerical simulations not only provide insights into the intricate interplay among various factors but also emerge as a crucial focal point for future research directions. In the realm of thermodynamic wakes, we delve into the thermal wake induced by the discharge of high-temperature cooling water and the cold wake resulting from the stirring of seawater. The generation, evolution, and ascent to the free surface of these wakes are explored. Additionally, this review identifies and analyzes current research shortcomings in each aspect. By systematically addressing existing knowledge gaps, our study contributes novel insights that propel academic progress and bear significant implications for submarine engineering. This work not only enhances our understanding of the intricate dynamics involved but also provides a foundation for future research endeavors in this critical field. [ABSTRACT FROM AUTHOR]

From fundamental research exploring molecular mechanisms to advanced endeavours like the development of artificial white blood cells, white blood cells have widespread applications due to their crucial role in safeguarding the body, defending against infection, and eliminating external pathogens, serving as indicators of several diseases. So, white blood cells must be separated efficiently with high purity to make the passive microdevices more effective for diagnostic applications. In this study, we investigated how cell concentration and viscosity collectively impact the margination of white blood cells in an inertial flow microchannel. We aim to improve white blood cell separation efficiency in microfluidic devices. Unlike previous studies that examined individual factors, this research focused on the interplay between bio-physical properties like cell interaction and viscosity. To explore their correlation, we diluted the blood with phosphate-buffered saline and viscoelastic fluid to manipulate the viscosity and cell concentration. Viscoelastic fluid improved white blood cells margination, while higher viscosity and low cell concentration decreased it. Maintaining blood-like viscosity, optimizing cell-free layer width, and promoting cell-cell interaction in the focusing zone collectively enhanced white blood cells margination.

This study aims to provide a comprehensive numerical solution and quantitative analysis of the thermal stratification and circulation in Fuxian Lake, the largest freshwater deep lake in China, utilizing a high-fidelity Environmental Fluid Dynamics Code (EFDC) to build a three-dimensional hydrodynamic model. Simulation results reveal that meteorological conditions and hydrodynamic processes notably influence the spatiotemporal characteristics of the thermocline, with wind and temperature disparities primarily impacting water flow. Maximum water temperature (24.3 °C) and thermocline intensity (0.31 °C/m) typically occur in September. Vertical circulation, driven by wind-induced horizontal divergence and convergence of lake currents, often induces uneven vertical movements, leading to thermocline irregularities. This study also assesses the sensitivity of Fuxian Lake to temperature changes, showcasing the efficacy of EFDC model in accurately reproducing observed spatiotemporal variations. This research not only establishes a foundation for integrating the EFDC model with water quality models but also presents an effective approach for studying hydrodynamics and thermal stratification processes in other deep-water lakes, thereby facilitating lake management and ecological restoration endeavors.

River water environmental capacity (RWEC) is an essential indicator of sustainable development. However, there are several studies on the dependence of RWEC on hydrological and hydraulic factors, especially self-cleaning ability. This study aims to clarify the role of self-cleaning factors in RWEC formation in a specific river basin. The method used in this study employed a set of models, including hydrological and eco-hydrodynamic models, with an added set of water quality parameters. The proposed research framework was applied to a specific river basin for four selected pollutants: NH4+, NO3-, PO43-, and BOD. The results revealed that the self-cleaning factors contributed significantly to the increase in RWEC. Specifically, RWECNH4+ improved by 22.6 % in the wet season and 22.7 % in the dry season; RWECNO3- improved by 10.22 % and 13.08 % in the wet and dry seasons, respectively; RWECPO43- exhibited the most significant improvement (143 % and 73 %, respectively), RWECBOD in the dry season decreased slightly by about 9%, the wet season increased by 88.34%. Our results demonstrate the critical role of self-cleaning factors in improving the carrying capacity, leading to developing medium- and long-term plans to preserve ecosystems in river systems in different basins.

The Sulejów reservoir is one of the largest reservoirs in Poland and is exposed to a large flux of nutrients from both point and diffuse sources, which leads to an excessive amount of eutrophication and cyanobacteria bloom. The underlying inspiration for this paper was to use a 1D HEC-RAS hydrodynamic model to improve the knowledge of sedimentation conditions and the chemistry of bottom sediments in the context of reservoir eutrophication and algae bloom. Field sampling was performed, and chemical concentrations of Total Organic Carbon, Total Phosphorus, and Cadmium were measured in samples from bottom sediments. The deepest parts of the reservoir and the presence of sediment traps coincide with the highest concentrations of organic carbon, nutrients, and heavy metals. The paper has shown that reservoir hydrodynamic modelling and precise bathymetry maps provide very valuable information that can be used for the interpretation of bottom sediment chemistry patterns and for understanding the conditions of sedimentation.

Inland waters play a key role in climate change studies, but choosing the correct tool to represent them is challenging. This paper discusses tool's applicability for predicting the impact of climate change on a lake's hydrodynamics. It aims to help determine the most suitable method to utilize. Three different tools, capable of representing the lake's hydrodynamics, were built and evaluated through the required input data quantity, the lake's hydrodynamic representation, and time consumption. Two climate change scenarios were simulated using the thermal stability curve, a unidimensional model (GLM), and a 3D mathematical model (Delft3D). The results were consistent, indicating an increase in the lake's temperature and the required energy to break the stratification, altering thermal patterns. The stability curve requires minimum input data and, with little computing time, can cover a larger simulation window. The unidimensional model requires more input data and knowledge, but with little simulation time, it shows the temperature profile, while the three-dimensional model provides gains in spatial variability representation; however, it needs more input data and advanced knowledge and is time-consuming. In lake management, it will be appropriate to combine the methods, using the curve to analyse the trend and delimitate the period for detailed study. HIGHLIGHTS The use of mathematical models in climate change studies.; How to compare the applicability of different tools used to predict climate change impacts on a lake's thermal stability.; The relevance of local field data.; How to achieve a solid tool evaluation.; Helps to understand the difference between methods, which are gains, the needed input data, and time-consuming.;

A vital process for converting heavy petroleum productions is Fluid Catalytic Cracking (FCC). As a major source of CO2 emissions, the regenerator reactor in the FCC unit accounts for about 20-35% of the refinery's total emissions. A common method for reducing CO2 emissions from the FCC regenerator is oxy-combustion, which has different advantages with regard to reducing energy penalties and associated costs. In this study, a computational fluid dynamic (CFD) study was used to examine the hydrodynamic characteristics of solid particles and gas inside the FCC regenerator, allowing CO2 to be captured more efficiently. Utilizing Ansys Fluent platform, the Eulerian-Eulerian model was applied with granular flow kinetic theory. In the simulations, different mesh sizes were tested, and the hydrodynamics of the oxy-combustion regenerator were evaluated by adjusting CO2 flow rates to achieve similar fluidization behaviors. The CFD results indicated that the conventional drag model accurately predicted the density phases within the bed. In oxy-combustion, CO2, due to its density, naturally creates a smaller dense phase compared to air-combustion. Moreover, optimizing the fluidizing gas velocities resulted in enhanced particle mixing, resulting in a distributed flow with vortices within the dense phases due to a reduction in gas velocity. To improve the environmental performance of the FCC unit, this research provides valuable insight into the hydrodynamics of solid catalysts used in the oxy-combustion process.