Search Results (385)

To prevent marine biofouling in seawater lift pumps, electrolyzed seawater containing Cu²⁺ needs to be injected into the pumps. This study employs Computational Fluid Dynamics (CFD) to simulate the variation in Cu²⁺ injection concentration required to achieve a Cu²⁺ concentration of 3 ppb within a 10 cm range around the pump under different operating conditions, including the installation of baffles and varying seawater flow rates. The simulation results demonstrate that CFD can accurately predict the distribution of Cu2+ concentration in electrolyzed seawater, with the distribution significantly influenced by seawater flow direction, necessitating reference to upstream data. When the lift pumps are idle, the required Cu²⁺ injection concentration increases with rising seawater flow rates, reaching 41.9 μg/L at the maximum flow rate of 1.9 m/s. During alternating pump operation, the required Cu²⁺ injection concentration also increases with the flow rate, significantly affected by the pump’s operational position: lower concentrations are required when the upstream pump is active compared to the downstream pump. Additionally, installing baffles around the pumps effectively mitigates the impact of seawater flow on Cu²⁺ distribution, significantly reducing the required injection concentration. This study provides theoretical and data-driven insights for optimising marine biofouling prevention in seawater lift pumps. Full article

Shrimp farming is practiced worldwide in tropical and subtropical regions, where shrimp often experience suboptimal temperatures during part of the production cycle, resulting in slower growth. A concentrated functional palatability enhancer (FPE) containing a mixture of chemoattractants was tested. A 12-week experiment at a suboptimal temperature (22 °C) was conducted with Penaeus vannamei (3.25 ± 0.02 g) in a clear water system (400 L with 40 shrimp per tank) with flow-through seawater. A standard diet was supplemented with 0, 1, and 2 g kg⁻¹ of FPE (STD, STD+1, and STD+2) with four replicates for each one. The inclusion of 1 g kg⁻¹ of FPE (STD+1) significantly increased the average final weight by 11.24% and weekly weight gain by 14,00% when compared to STD. The highest tested dose (2 g kg⁻¹) did not result in further improvement in growth performance compared to the control. In addition, the total hemocyte count (THC) remained at an optimal level for the species in the STD+1 treatment under suboptimal temperature conditions compared to the other treatments. We also observed a decrease in Vibrio spp. bacterial counts in STD+1 compared to STD+2. Therefore, the lowest tested dose was shown to positively influence the rearing of P. vannamei at suboptimal temperatures. Full article

This study addresses the challenge of solid pollutant collection in seawater pond recirculating aquaculture by designing a novel funnel-shaped sewage collection device and evaluating its performance through Computational Fluid Dynamics (CFD) simulations and experimental validation. The results reveal that the device forms a rotating flow field, effectively concentrating solid particles in a central low-velocity zone with a diameter of approximately 2 m when the sewage pump is inactive. The optimal bottom dip angle for efficient sewage discharge is determined to be 21 degrees, with flow velocities near the outlet ranging between 0.031 and 0.062 m per second, sufficient to mobilize particles smaller than 5 mm. Prototype testing demonstrates a solid pollutant collection efficiency of 75.7 percent, confirming the device’s practical effectiveness in improving water quality and operational performance. This research offers a validated and efficient solution for solid waste management in aquaculture systems. Full article

Based on the sewage pipe network system in the service area of Qianshan-Gongbei Plant in Zhuhai City, the characteristics of water quality and quantity were analyzed, and the common problems were diagnosed. Through the establishment of a hydraulic-water quality model, the flow state of sewage in the pipe network is simulated, and the actual data is checked. It is found that there are significant differences in the quantity and quality of sewage pipe network systems in different seasons and land use types, and there is an obvious seawater backflow phenomenon in coastal areas. To solve these problems, this paper puts forward a series of optimization suggestions to improve the operation efficiency of sewage treatment plants and the reliability of urban drainage systems. Full article

To achieve efficient prediction and optimization of the energy consumption of ship central cooling systems, this paper first constructed and validated a high-precision multi-physical domain simulation model of the ship central cooling system based on fluid heat transfer principles and the physical network method. Then, simulation experiments were designed using the Box–Behnken design (BBD) method to study the effects of five key parameters—main engine power, seawater temperature, seawater pump speed, low-temperature fresh water three-way valve opening, and low-temperature fresh water flow rate—on system energy consumption. Based on the simulation data, an energy consumption prediction model was constructed using response surface methodology (RSM). This prediction model exhibited excellent goodness of fit and prediction ability (coefficient of determination R² = 0.9688, adjusted R²_adj = 0.9438, predicted R²_pred = 0.8752), with a maximum relative error of only 1.2% compared to the simulation data, confirming its high accuracy. Sensitivity analysis based on this prediction model indicated that main engine power, seawater pump speed, seawater temperature, and three-way valve opening were the dominant single factors affecting energy consumption. Further analysis revealed a significant interaction between main engine power and seawater pump speed. This interaction resulted in non-linear changes in system energy consumption, which were particularly prominent under operating conditions such as high power. This study provides an accurate prediction model and theoretical guidance on the influence patterns of key parameters for the simulation-driven design, operational optimization, and energy saving of ship central cooling systems. Full article

AgO-Al batteries generate substantial heat during discharge, and inadequate heat dissipation can degrade battery performance and pose thermal runaway risks. To meet thermal control requirements for experimental scenarios, a feedback-controlled thermal management system was developed. Computational fluid dynamics was employed to analyze the effects of seawater flow rate, seawater temperature, electrolyte flow rate, and initial electrolyte temperature on electrolyte outlet temperature and heat dissipation capacity. Results indicate that heat dissipation capacity is negatively correlated with seawater temperature and positively correlated with electrolyte inlet temperature. It increases with higher seawater and electrolyte flow rates, though the increase becomes negligible when the seawater flow rate exceeds 10 m/s. The designed system adapts to dynamic operating conditions via real-time parameter tuning. Experimental validation confirms its effectiveness in regulating electrolyte outlet temperature, achieving steady-state control accuracy within ±3 °C and a dynamic response time of less than 7 min—meeting thermal management requirements for battery test benches. This study provides critical data and technical support for developing temperature control technologies and performance testing of seawater-activated batteries. Full article

Domestic showers are critical points of human exposure to microbial biofilms, which may harbor opportunistic pathogens such as Legionella spp. and nontuberculous Mycobacterium. However, biofilm development in reverse osmosis (RO)-treated drinking water systems remains poorly understood. We tested whether shower plumbing material (flexible polymer hose versus showerhead with inline polyethersulfone filter) and seasonal water variations influence biofilm community assembly. In a controlled field study, commercial shower systems were deployed in households supplied with RO-treated tap water from the KAUST Seawater Desalination Plant; biofilm samples were collected from hoses and filters over 3–17 months. Flow cytometry and 16S rRNA gene amplicon sequencing characterized microbial abundance, diversity, and taxonomic composition. We found that alpha diversity, measured by observed OTUs, was uniformly low, reflecting ultra-low biomass in RO-treated tap water. Beta diversity analyses revealed clear clustering by material type, with hoses exhibiting greater richness and evenness than filters. Core taxa—Pelomonas, Blastomonas, and Porphyrobacter—dominated both biofilm types, suggesting adaptation to low-nutrient, chlorinated conditions. Overall, our results demonstrate that ultra-low-nutrient RO tap water still supports the formation of material-driven, low-diversity biofilms dominated by oligotrophic taxa, underscoring plumbing-material choice as a critical factor for safeguarding shower water quality. These findings advance our understanding of biofilm ecology in RO-treated systems, informing strategies to mitigate potential health risks in shower water. Full article

Forward osmosis (FO) is a membrane separation process driven by the osmotic pressure difference between a high-salinity draw solution (DS) and a low-salinity feed solution (FS). This pressure-free dewatering method is highly energy efficient, making it suitable for concentration and resource recovery. However, conventional FO systems using series-connected modules suffer from progressive DS dilution and FS concentration, leading to a reduction in the osmotic driving force and thereby limiting the overall performance. To address this issue, we propose a novel hybrid FO module configuration in which the FS flows in series while the DS is split and distributed in parallel across moules. This configuration was evaluated using an experimentally validated FO module model and RO simulation tools. Under seawater (600 mM NaCl) as DS and brackish water (10 mM NaCl) as FS, a conventional three-stage FO module achieved an enrichment ratio of 2.5 with an energy consumption of 0.151 kWh/m³. In contrast, the proposed draw solution split distribution (DSSD) achieved an enrichment ratio of 12.5 at a reduced energy consumption of 0.137 kWh/m³. In comparison, a reverse osmosis system consuming 0.58 kWh/m³ achieved a similar enrichment ratio of 12.3. These results demonstrate the high energy efficiency and dewatering capacity of the proposed FO configuration, highlighting its potential for industrial applications in food processing, beverage production, pharmaceuticals and agriculture. Full article

Over the past two decades, extensive coastal development in China has led to numerous small-scale enclosed coastal water bodies. Due to complex shoreline geometries, these areas suffer from disturbed hydrodynamic conditions, weak water exchange, which quickly leads to sediment accumulation, and difficulty maintaining ecological water levels, posing serious environmental threats. Enhancing seawater exchange capacity and achieving coordinated optimization of exchange efficiency and ecological water level are critical prerequisites for the environmental restoration of eutrophic enclosed coastal areas. This study takes the Ligao Block in Tianjin as a case study and proposes a real-time sluice gate regulation scheme. By incorporating hydrodynamic conditions, engineering layout, and present characteristics of the benthic substrate environment, the number, width, location, and operation modes of sluice gates are optimized to maximize water exchange efficiency while maintaining natural flow patterns. The result of the numerical simulation of hydrodynamic exchange and intelligent optimization analysis reveals that the optimal sluice gate operation strategy should be tailored to regional tidal flow characteristics and substrate conditions. Through intelligent scheduling of exchange sluice gates, systematic gate parameter optimization, and active control of gate opening, this approach achieves intelligent seawater exchange, optimized flow dynamics, active exchange, and sustained ecological water levels in enclosed coastal water bodies. Full article

A more precise definition of groundwater dynamics is an urgent issue for developing reliable plans to assist in the sustainable management of these resources. The combination of remote sensing input data with groundwater flow models emerges as a tool capable of representing these dynamics and simulating important conditions for developing adequate groundwater exploitation plans. These technologies allow for a more detailed and accurate analysis of the interactions between the factors influencing aquifers’ behavior, such as climate variability and anthropogenic pressure on water resources. Thus, the present study aims to develop a numerical model of groundwater flow in the aquifers of the Recife Metropolitan Region, state of Pernambuco, in Brazil, to evaluate the dynamics of these waters and the piezometric level drawdowns between 2004 and 2023. The FREEWAT platform, which applies the MODFLOW-2005 code, was used to simulate the study area. The results showed the entry of seawater into some formations and drawdowns that reached more than 100 m at some points, indicating the urgent need for management strategies to mitigate salinization and preserve the quality of the region’s groundwater resources. Full article

Static mixers have been widely used in marine research fields, such as marine control systems, ballast water treatment systems, and seawater desalination, due to their high efficiency, low energy consumption, and broad applicability. However, the turbulent mixing process and fluid–wall interactions involving complex structures make the mixing transport characteristics of static mixers complex and nonlinear, which affect the mixing efficiency and stability of the fluid control device. Here, the modeling and design optimization of the two-phase flow mixing and transport dynamics of a static mixer face many challenges. This paper proposes a modeling and problem-solving method for the two-phase flow transport dynamics of static mixers, based on the lattice Boltzmann method (LBM) and large eddy simulation (LES). The characteristics of the two-phase flow mixing dynamics and design optimization strategies for complex component structures are analyzed. First, a two-phase flow transport dynamics model for static mixers is set up, based on the LBM and a multiple-relaxation-time wall-adapting local eddy (MRT-WALE) vortex viscosity coupling model. Using octree lattice block refinement technology, the interaction mechanism between the fluid and the wall during the mixing process is explored. Then, the design optimization strategies for the flow field are analyzed under different flow rates and mixing element configurations to improve the mixing efficiency and stability. The research results indicate that the proposed modeling and problem-solving methods can reveal the dynamic evolution process of mixed-flow fields. Blade components are the main driving force behind the increased turbulent kinetic energy and induced vortex formation, enhancing the macroscopic mixing effect. Moreover, variations in the flow velocity and blade angles are important factors affecting the system pressure drop. If the inlet velocity is 3 m/s and the blade angle is 90°, the static mixer exhibits optimized overall performance. The quantitative analysis shows that increasing the blade angle from 80° to 100° reduces the pressure drop by approximately 44%, while raising the inlet velocity from 3 m/s to 15 m/s lowers the outlet COV value by about 70%, indicating enhanced mixing uniformity. These findings confirm that an inlet velocity of 3 m/s combined with a 90° blade angle provides an optimal trade-off between mixing performance and energy efficiency. Full article

Microfluidic techniques have emerged as promising, efficient, cost-effective, and environmentally friendly desalination solutions. By utilizing fluid dynamics at the microscale, these techniques offer precise control over chemical, biological, and physical processes, presenting advantages such as reduced energy consumption, miniaturization, portability, and enhanced process control. A significant challenge in scaling microfluidic desalination for macro applications is the disparity in flow rates. Current devices operate at microliters per minute, while practical applications require liters daily. Solutions involve integrating multiple units on a single chip and developing stackable chip designs. Innovative designs, such as 3D microfluidic chips, have shown promise in enhancing scalability. Fouling, particularly in seawater environments, presents another major challenge. Addressing fouling through advanced materials, including graphene and nanomaterials, is critical to improving the efficiency and longevity of devices. Advances in microfluidic device fabrication, such as photo-patterned hydrogel membranes and 3D printing, have increased device complexity and affordability. Hybrid fabrication approaches could further enhance membrane quality and efficiency. Energy consumption remains a concern, necessitating research into more energy-efficient designs and integration with renewable energy sources. This paper explores various electrochemical-based microfluidic desalination methods, including dialysis/electrodialysis, capacitive deionization (CDI)/electrochemical capacitive deionization (ECDI), ion concentration polarization (ICP), and electrochemical desalination (ECD). Full article

This work aims to characterize flow-accelerated corrosion of carbon steel A36 coupons exposed to simulated treated reverse-osmosis seawater under ambient conditions and a Reynolds number range of 6000 to 25,000 using a standard corrosion testing method. The flow behavior in the corrosion compartment and the turbulent parameters were determined by computational fluid dynamics simulation. Using selected flow parameters, complemented with experimental corrosion rate measurements, the oxygen mass transfer coefficients (m_c) and the rate constant for the cathodic reaction (k_c) at the coupon surface were determined. As expected, m_c depends only on the fluid conditions, while k_c is highly influenced by interface resistance, leading to significantly different runs with and without a corrosion inhibitor. The dissimilar fluid flow distribution on intrados and extrados generates irregular corrosion patterns, depending on the angular position of the coupon inside the corrosion compartment. Morphological studies using scanning electron microscopy and atomic force microscopy support simulation results. Full article

Docosahexaenoic acid (DHA), a long-chain polyunsaturated fatty acid, plays a critical role in animal growth, inflammatory regulation, lipid metabolism, and neurological functions. However, the optimal dietary requirement of DHA for tiger puffer remains unknown. This study systematically investigated the effects of different dietary DHA levels on the growth performance, body composition, hematological parameters and tissue physiology of tiger puffer (average initial body weight 17.78 ± 1.92 g). Six experimental diets with graded DHA concentrations (0.09%, 0.57%, 1.35%, 1.61%, 2.28%, and 3.08% dry matter) were formulated. The feeding experiment was carried out in a seawater flow-through system for eight weeks, with each diet assigned to three replicate tanks. Based on the regression analysis of weight gain and specific growth rate, the maximum values were observed at the dietary DHA level of 1.75% and 1.88%, respectively. Appropriate DHA levels also significantly improved the muscle protein synthesis and lipid metabolism, and strengthened the intestinal morphology. Furthermore, a threshold for efficient DHA deposition in muscle was identified, beyond which excess DHA (3.08%) may be β-oxidized and therefore largely wasted. In conclusion, the optimal dietary DHA level for juvenile tiger puffer should be within the range of 1.75–1.88%. Full article

Solar-driven interfacial evaporation has emerged as a sustainable and highly efficient technology for seawater desalination, attracting considerable attention for its potential to address global water scarcity. However, challenges such as low evaporation rates and salt accumulation significantly hinder the performance and operational lifespan of evaporators. Here, we present an innovative Janus-structured evaporator featuring distinct operational mechanisms through the integration of a hydrophobic PVDF-HFP@PPy photothermal membrane and a hydrophilic PVA-CF@TA-Fe³⁺ hydrogel, coupled with a unidirectional flow configuration. Distinct from conventional Janus evaporators that depend on interfacial water transport through asymmetric layers, our design achieves two pivotal innovations: (1) the integration of a lateral fluid flow path with the Janus architecture to enable sustained brine replenishment and salt rejection and (2) the creation of dual vapor escape pathways (hydrophobic and hydrophilic layers) synergized with hydrogel-mediated water activation to elevate evaporation kinetics. Under 1 sun illumination, the evaporator achieves a maximum evaporation rate of 2.26 kg m⁻² h⁻¹ with a photothermal efficiency of 84.6%, in both unidirectional flow and suspension modes. Notably, the evaporation performance remains stable across a range of saline conditions, demonstrating remarkable resistance to salt accumulation. Even during continuous evaporation of highly saline water (10% brine), the evaporator maintains an evaporation rate of 2.10 kg m⁻² h⁻¹ without observable salt precipitation. The dual anti-salt strategies—enabled by the Janus structure and unidirectional flow design—underscore the evaporator’s capability for sustained high performance and long-term stability in saline environments. These findings provide valuable insights into the development of next-generation solar evaporators that deliver high performance, long-term stability, and robustness in saline and hypersaline environments. Full article