Water Entry Research Articles

Involvement of aquaporins in Shiga toxin-induced swelling and water transport dysfunction in human renal microvascular endothelial cells

One of the hallmarks of Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) is kidney damage. Our previous research demonstrated that Shiga toxin type 2 (Stx2a) decreases cell viability and induces swelling of human glomerular endothelial cells (HGEC). However, Stx2a can disrupt net water transport across HGEC monolayers without affecting cell viability. This work aimed to elucidate the possible mechanisms involved in the water transport disruption caused by Stx2a across HGEC monolayers. We investigated paracellular and transcellular water transfer across HGEC by analyzing the passage of FITC-Dextran and the hydrostatic pressure (Phydr) and measuring the osmotic pressure (Posm), respectively. Stx2a selectively affected the transcellular pathway without impacting the paracellular route. Furthermore, Stx2a cell swelling was prevented by pretreatment with aquaporin inhibitors tetraethylammonium chloride (TEA), Mercury (II) chloride (HgCl2) or TGN-020, suggesting aquaporin involvement in this process. Confocal microscopy revealed that Stx2a increased HGEC total volume, which TEA and TGN-020 counteracted. Additionally, we identified in HGEC not only the expression of aquaporin-1 (AQP1) but also the expression of aquaporin-4 (AQP4). Surprisingly, we observed a decrease in the expression of both AQPs after Stx2a exposure. Our findings suggest that Stx2a may induce water movement into HGEC via AQP1 and AQP4, increasing total cell volume. Subsequently, decreased AQP1 and AQP4 expression could inhibit transcellular water transfer, potentially as a protective mechanism against excessive water entry and cell lysis.

The Role of Seed Characteristics on Water Uptake Preceding Germination

Seed germination is a complex process involving imbibition, activation and subsequent growth. In addition to re-establishing metabolic activity, water uptake helps stabilize macromolecules and biochemical reactions, resulting in radicle protrusion. Factors affecting water uptake include seed composition, water availability and seed coat permeability. Water entry sites vary with species and occur primarily through the hilum, micropyle or lens. In addition, seed size influences water uptake, where larger seeds are usually less permeable. The seed coat plays a significant role in regulating the water absorption process. Several seed coat characteristics, including color, thickness and differences in the anatomical structure, such as the presence of pores, cuticles and radicle pockets, alter water permeability. Similarly, the presence of either physical or physiological seed dormancy negatively affects water uptake. This review emphasizes that understanding seed characteristics, such as size, shape and seed coat permeability, and their relationships is essential for breeding and selecting seeds with desirable traits, as they directly influence water uptake, leading to improved germination and growth.

Dynamic fluid-structure interaction between the projectile and the light-thin ice under the motion state in the polar environment

The interaction between projectiles and ice during water entry is crucial for advancing polar resource exploration and military operations in polar regions. This study introduces a fluid-structure interaction (FSI) model to simulate the dynamics between projectiles and light-thin ice under a motion state, validated through laboratory experiments. It examines the cavity evolution patterns during water entry and analyzes the motion states and dynamic characteristics of both the projectile and the floating ice. The influence of the horizontal-to-vertical velocity ratio (u*) and the initial pitch angle (φ) on the water entry process and collision dynamics has also been considered. The results reveal that as the projectile approaches the floating ice, it generates a wave-making effect, impacting the formation of the water entry splash crown and the deflection motion of the ice. Additionally, the hydrodynamic force acting on the projectile increases by 40 % compared to free water entry conditions. After the collision between the projectile and the light-thin ice, the pinch-off characteristics of the water entry cavity alter. This collision influences the motion state and dynamic characteristics of the projectile, while the ice experiences both collision and hydrodynamic forces, leading to passive motion. With an increasing water entry velocity ratio, the light-thin ice forms an expanding cavity during passive water entry, affecting the cavity pinch-off of the projectile. When u* > 1, the projectile exhibits circuitous motion post-collision with the ice. Variations in water entry angles of the projectile alter the collision mode between the projectile and the ice, resulting in changes to their motion states and dynamic characteristics. A critical pitch angle exists during the cavity pinch-off process.

In Situ Conductive Heating for Thermal Desorption of Volatile Organic-Contaminated Soil Based on Solar Energy

A novel conductive heating method using solar energy for soil remediation was introduced in this work. Contaminated industrial heritage sites will affect the sustainable development of the local ecological environment and the surrounding air environment, and frequent exposure will have a negative impact on human health. Soil thermal desorption is an effective means to repair contaminated soil, but thermal desorption is accompanied by a large amount of energy consumption and secondary pollution. Therefore, a trough solar heat collection desorption system (TSHCDS) is proposed, which is applied to soil thermal desorption technology. The effects of different water inlet temperature, water inlet velocity and soil porosity on the evolution of soil temperature field were discussed. The temperature field of contaminated soil can be numerically simulated, and a small experimental platform is built to verify the accuracy of the numerical model for simulation research. It is concluded that the heating effect is the best when the water entry temperature is the highest, at 70 °C, and the temperature of test point 4 is increased by 50.71% and 1.42%, respectively. When the inlet water flow rate is increased from 0.1 m/s to 0.2 m/s, the heating effect is significantly improved; when the inlet water flow rate is increased from 0.5 m/s to 1.5 m/s, the heating effect is not significantly improved. Therefore, when the flow rate is greater than a certain value, the heating effect is not significantly improved. The simulation analysis of soil with different porosity shows that larger porosity will affect the thermal diffusivity, which will make the heat transfer effect worse and reduce the heating effect. The effects of soil temperature distribution on the removal of petroleum hydrocarbon C6–C9 and trichloroethylene (TCE) were studied. The results showed that in the thermal desorption process of petroleum hydrocarbon C6–C9-contaminated soil, the removal rate of pollutants increased significantly when the average soil temperature reached 80 °C. In the thermal desorption of trichloroethylene-contaminated soil, when the thermal desorption begins, the soil temperature rises rapidly and reaches the target temperature, and a large number of pollutants are removed. At the end of thermal desorption, the removal of both types of pollutants reached the target repair value. This study provides a new feasible method for soil thermal desorption.

Fluid–structure interaction analysis of curved wedges entering into water

The water entry of wedges with curvature differs significantly from that of linear wedges, which have been fully investigated and formulated. The safety and integrity of structures prompt an urgent investigation into the mechanism by which the curvature affects slamming loads and structural responses during water entry. This study examines the slamming force characteristics, pressure distributions, fluid jet evolutions, and structural response behaviors of two-dimensional curved wedge sections, considering five different curvatures and two panel thicknesses. A two-way coupling fluid–structure interaction (FSI) solver has been proposed within an open-source framework. The FSI solver was validated against published literature to ensure its high-fidelity. The small deadrise angle results in a more complicated time-domain characteristics for the slamming pressure, with a gradual transition from a single peak to a double peak. The half-peak pressure duration time were defined, and the quantitative results reveal that the hydroelastic effect of the linear wedge is significantly higher than the curved wedges. When considering the geometric curvature, the elastic wedges do not consistently reduce the peak slamming pressure and lengthen the pulse time. Additionally, large deformations generated by the panel vibrations alter the evolutionary pattern of the fluid jet. In contrast to the linear wedge, the structural responses of the curved wedges show distinctive two-stage behaviors.

Numerical investigation on the slamming loads of a truncated trimaran hull entering regular waves

For ship slamming, waves can disturb the water entry progress and thus affect the slamming load characteristics. This paper studied the slamming loads of a trimaran entering regular waves based on the CFD method. The results of a trimaran model impacting calm water and wedge impacting waves are used to verify the present method. The free surface evolution and load characteristics of the trimaran model considering wave effects are discussed. The results showed that the position at which the structure touches the wave surface depends on the formation, deformation and escape of bubble flows, which cause obvious asymmetrical flow. The enclosure of the air cavity induces a step increase in pressure, and the pressure peak appears when the bubble fully escapes. Three typical positions, wave crest, wave cross and wave through, are chosen to explore the influence of waves on slamming loads. The impact load shows a 98% difference at different wave locations. In ship load forecasting, the position of the waves relative to the hull is noteworthy. The influence of the water entry velocity on the slamming load is further discussed. Bubble retention related to the water entry velocity is the key factor affecting the peak load.

Ecological health evaluation of an urban riverside greenway based on the AHP-EWM-TOPSIS model: a case study of Hangzhou, China

Abstract Riverside greenways are complex artificial–natural composite ecosystems that occupy significant linear open spaces in urban areas. Healthy riverside greenways promote public health and improve urban environmental quality. This study developed an evaluation system with four criteria layers and 31 indicators, using a comprehensive method that combines the analytical hierarchy process (AHP), entropy weight method (EWM), and technique for order preference by similarity to ideal solution (TOPSIS) to assess the ecological health of the Shangtang River greenway in Hangzhou, China. Additionally, structural equation modeling analyzed key factors influencing riverside greenway health and their pathways. Redundancy analysis (RDA) was used to explore how design and non–design factors affect the ecological health of riverside greenways. The results showed health values for different sections of the riverside greenway ranging from 0.16 to 0.69. The use of ecological design techniques was the main factor causing significant variations in health values across sampling plots. Specifically, ecological revetments, the slope of terrain at water entry, and ecological conservation measures positively impacted the ecological health of the riverside greenway, while non–native invasive plants and building density had negative effects. Non–design factors, such as physical states, also play an equally important role in the ecological health of urban riverside greenways. Effectively assessing the ecological health of these greenways is essential for developing management strategies. This study presents a novel framework for evaluating the ecological health of urban riverside greenways by quantifying indicators related to the regional environment, physical conditions, management practices, and design techniques. It quantitatively analyzes how landscape design techniques contribute to ecological health and serves as an empirical tool for improving urban waterfront environments and advancing riverside greenway construction and management.

The Rate of Water Safety Team Interventions in High Diving, A Survey of Elite Athletes Performing between 2009 and 2021

Abstract There is a paucity of sport-specific safety data on high diving. This paper describes the results of a survey of all athletes competing in elite international competitions between 2009 and 2021. Sixty-eight athletes completed surveys, representing a response rate of 80%. The rate of water safety team interventions was calculated at one intervention per 295 high dives for the men (0.34%) and one intervention per 265 high dives for the women (0.38%). After safety team intervention, 26% of the male and 42% of the female divers required hospital evaluation. Circumstances reported by high divers that may contribute to an incident were performing a new dive (<10 repetitions), body position at water entry, and environmental factors such as water movement and cold ambient temperature. Statistically, a water safety team will intervene once or twice per 4-d tournament. Injury and illness surveillance both during tournaments and year-round is recommended.

Slamming characteristics of a rigid wedge during symmetric and asymmetric water entry

Abstract The slamming behavior of structures entering water is crucial for understanding wave loads on marine structures. To investigate the spatiotemporal evolution characteristics of vertical symmetric and asymmetric water slamming loads on wedges, a series of tests were conducted on rigid wedges with deadrises of 20° and 30°. During asymmetric water entry, the wedge was heeled by 5° and 10° along the Z-axis. The experimental results indicate that velocity loss and the pressure error is less than 5%. Furthermore, the peak pressure decreases with the effective deadrise increase. The analysis is discussed in the paper. The slamming behavior of structures entering water is crucial for understanding wave loads on marine structures. To investigate the spatiotemporal evolution characteristics of ver-tical symmetric and asymmetric water slamming loads on wedges, a series of tests were conducted on rigid wedges with deadrises of 20° and 30°. During asymmetric water entry, the wedge was heeled by 5° and 10° along the Z-axis. The experimental results indicate that velocity loss and the pressure error is less than 5%. Furthermore, the peak pressure decreases with the effective deadrise increase. Relevant quantitative analysis is discussed in the article.

Study on water entry impact characteristics and parameter influence analysis of the vehicle passing through the thin crushed ice zone in a polar environment

The problem of water entry in polar environments holds significant research value for polar resource exploration and military applications. This study uses computational fluid dynamics and the discrete element method (CFD-DEM) to investigate the complex process of a vehicle entering water through a thin crushed ice zone. Experimental data validates the efficiency of the coupling algorithm. The primary focus of this study is to investigate the influence of crushed ice shapes, arrangement patterns, coverage densities, and sizes within thin crushed ice zones on the process of water entry. A comprehensive analysis is carried out to assess how the characteristic parameters of different thin crushed ice zones affect the dynamic behavior of the vehicle during water entry and the movements of the crushed ice. Concurrently, the influence of different velocities of the vehicle on the water entry process through a specific thin crushed ice zone is analyzed. The results show that when the crushed ice is in a regular arrangement, it exhibits a circular immersion phenomenon and a cross-shaped passive movement trend. The arrangement patterns, coverage densities, and sizes of the crushed ice have different effects on the water entry process. Of these factors, the complexity of the influence of crushed ice sizes on the water entry process stands out. Meanwhile, the water entry velocity plays a crucial role in determining the relative significance of the hydrodynamic force and the collision force of crushed ice on the total resistance of the vehicle during water entry. These insights provide valuable guidance for the planning and execution of missions in polar regions.

Experimental investigation on the water-entry characteristics of the structure passing through the broken ice field

In this study, experiments are conducted on the process of a structure entering water under an ice-free environment and a broken ice field environment with three different broken ice densities based on a water-entry experimental platform. The influences of the broken ice field environment and different broken ice densities on the variations in the cavity morphology and movement features of water entry into the structure are investigated. The results show that the broken ice field environment postpones the surface closure of the cavity, leading to an increase in the size of the closed cavity, which, in turn, affects the cavity collapse process, slows down the overall collapse of the cavity, and is conducive to the cavity formation of the structure. In addition, when the density of broken ice is 30%, the influence of the broken ice field on the variations in the cavity morphology is not significant. When the density of broken ice increases to 70%, the expansion, cavity closure, and collapse are significantly different from those in an ice-free environment. Necking and deep closure occur. Some broken ice is drawn into the cavity, accelerating the cavity collapse. The effect of the broken ice field environment on the motion stability of the structure entering the water increases with an increase in broken ice density. When the density of broken ice increases to 50 and 70%, owing to the direct collision between the structure and broken ice, mutual forces and momentum transfer are generated. This results in a horizontal displacement of the trajectory of the structure, a sudden decrease in velocity, and an acceleration of velocity attenuation, ultimately affecting the motion stability and drag reduction characteristics of the structure.

1H, 15N and 13C resonance assignments of the S2A and H64A double mutant of human carbonic anhydrase II.

Protein-water interactions profoundly influence protein structure and dynamics. Consequently, the function of many biomacromolecules is directly related to the presence and exchange of water molecules. While structural water molecules can be readily identified through X-ray crystallography, the dynamics within functional protein-water networks remain largely elusive. Therefore, to understand the role of biological water in protein dynamics and function, we have introduced S2A and H64A mutations in human Carbonic Anhydrase II (hCAII), a model system to study protein-water interactions. The mutations of serine to alanine at position 2 and histidine to alanine at position 64 cause an increase in hydrophobicity in the N-terminus and active site loop thereby restricting water entry and disrupting the water network in the Zn2+-binding pocket. To pave the way for a detailed investigation into the structural, functional, and mechanistic aspects of the Ser2Ala/His64Ala double mutant of hCAII, we present here almost complete sequence-specific resonance assignments for 1H, 15N, and 13C. These assignments serve as the basis for comprehensive studies on the dynamics of the protein-water network within the Zn2+-binding pocket and its role in catalysis.

A general solution for the water entry of an arbitrary curved wedge

ABSTRACT The present study proposes a general solution for the water entry of an arbitrary curved wedge with a constant speed. The solution is based on the assumption that the impact flow is an incompressible potential flow with negligible effects of gravity and surface tension. The slamming and transition stages of the water entry of the curved wedge are addressed theoretically. For the slamming stage, pressure and hydrodynamic force models are derived from a quasi self-similar assumption based on the wetted length and a similarity solution of the water entry of linear wedges. The solution can be applied to the water entry of linear and curved wedges, where the curvature effects are absorbed into the wetted length and the derivative of the wetted length with respect to the penetration depth. For the transition stage, where a fixed separation point of flow detachment is located at the knuckle of the wedge, a hydrodynamic force model is proposed by extending the transition stage model of the water entry of linear wedges to that of curved wedges. The present solution can quickly predict the pressure distributions and hydrodynamic forces for the water entry of curved wedges. The predictions are in good agreement with the experimental and numerical results for the slamming and transition stages.

Water entry of solid cylinders: a new approach to investigate the density ratio

Water entry of solid cylinders: a new approach to investigate the density ratio

Automatic classification method for water entry sounds in multi-interference environments

Abstract In marine environments with strong pulse interference, distinguishing water entry sounds from pulse interference with high accuracy presents a challenge. Conventional algorithms that only utilize the singular values of intrinsic mode functions (IMFs) as the classification feature can have many misclassified signals in noisy environments. To identify the water entry sound more precisely, this study introduces a classifier based on selected singular value and correlation coefficient features. Specifically, the correlation coefficient between each IMF and the original signal are used to select crucial singular values and eliminate uninformative components. Furthermore, the correlation coefficient also combines with singular values as classification features for water entry sounds. The classification experiment results of 2460 groups of water entry sound and pulse interference indicate that the proposed classifier improves classification accuracy by approximately 11.5% compared to using singular values alone and by approximately 2.4% compared to classification accuracy without eliminating uninformative IMFs.

An immersed multi-material arbitrary Lagrangian–Eulerian finite element method for fluid–structure-interaction problems

Fluid–structure-interaction (FSI) phenomena are widely concerned in engineering practice and challenge current numerical methods. In this article, the finite element method is strongly coupled with the multi-material arbitrary Lagrangian–Eulerian (MMALE) method to develop a monolithic FSI method named the immersed multi-material arbitrary Lagrangian–Eulerian finite element method (IALEFEM). By immersing the finite elements in the MMALE computational grid, the fluid–solid interface is directly tracked by the element boundary with accurate normal directions. The fluid–structure-interaction is implicitly implemented by assembling the nodal variables and updating the Lagrangian momentum equation on the MMALE grid. Combining the advantages of both MMALE and FEM with the immersed boundary method, the IALEFEM is effective for solving complicated FSI problems with multi-material fluid flow. A slip fluid–structure-interaction method is also proposed to enhance the computational accuracy in simulating FSI problems with significantly different velocity fields. The accuracy and effectiveness of the IALEFEM are verified and validated by several benchmark numerical examples including the shock-cylinder obstacle interaction, flexible panel deformation induced by shock wave, dam break problem with large structural deformation, water entry of a wedge, fragmentation of a cylinder shell induced by blast, response of elastic plate subjected to spherical near-field explosion and structural damage of open-frame building under blast loading.

Numerical investigation of vehicle water entry with angle of attack

This paper investigates the water entry of a vehicle with angle of attack (AOA) through numerical methods, employing the volume-of-fluid multiphase flow model and overset grid technique. The validity of the numerical model is confirmed through experimental verification. Building upon this, the study analyzes the motion characteristics, cavity evolution, and flow field distribution of the vehicle during water entry, considering the influence of AOA and falling velocity. Numerical findings indicate that the collapse of the right side of the cavity induces a transient lateral force on the vehicle, resulting in vehicle tilting. Moreover, an increase in initial velocity delays vehicle tilt, while an increase in AOA reduces vehicle motion stability, leading to earlier tilting. Initially, the vehicle rotates counterclockwise around the Oz axis of the projectile coordinate system. Subsequent to cavity collapse, the vehicle experiences an opposing moment, leading to a reduction in rotation speed and eventual rotation in the opposite direction. Water impact triggers sudden changes in the vehicle's lift and drag coefficients, while cavity sticking induces a minor abrupt change in the lift coefficient. Following cavity collapse, both lift and drag coefficients exhibit significant oscillations. Unlike typical cavity collapse phenomena, the flow field on the right side of the vehicle undergoes alternating high-pressure and low-pressure regions.

Compound cavity formation and splash crown suppression by water entry through proximally adjacent polystyrene beads

We move forward the important topic of water entry by documenting splash dynamics arising from the impact of hydrophilic spheres with buoyant millimetric microplastics, mimicked in our study by polystyrene beads. Collision with small, buoyant beads is yet another means to manipulate splash dynamics. In this experimental study, we investigate the fluid–structure interactions between beads and hydrophilic spheres for Froude numbers in the range of 20−100. Generally, hydrophilic spheres entering a liquid bath below the critical velocity of 8 m/s produce minimal fluid displacement and no cavity formation. The presence of proximally adjacent beads atop the fluid with respect to impacting spheres promote flow separation and compound cavities for sufficiently large Froude numbers, while suppressing the growth of splash crowns. Compound cavities consist of a shallow, quasi-static first cavity that seals near the water line, and a second, deeper cavity produced in the wake of descending spheres. A vertically protruding Worthington jet follows cavity collapse. The resulting splash metrics differ from those of hydrophobic spheres with respect to the properties of impacted beads. We find impactors traversing a deep liquid pool layered with beads experience drag reduction when compared to entry into a clean pool due to the drag-reducing benefits of flow separation while not offering a high inertial penalty. Our study unravels the physics behind the widely encountered interaction of solid projectiles impacting passively floating particles, and our results translate to the entry dynamics of water-diving creatures and projectiles into water bodies polluted by floating millimetric microplastics.

Numerical study on the motion characteristics of free fall lifeboats entering calm water and rough sea

As ocean engineering operations extend into deeper seas, the working environment becomes increasingly complex, making free fall lifeboats (FFLBs) more vital for maritime disaster rescues. Unlike traditional davit-launched lifeboats, FFLBs are propelled into the water at a specific velocity and angle, engaging in a complex motion process of launch, impact, submersion, and resurfacing. Therefore, to assess the safety of FFLBs, this paper regarding the lifeboat as a rigid body aims to investigate the six-degree-of-freedom motion characteristics of lifeboat entering the water with different entry angles θ and wave environment, with a specific focus on analyzing the primary causes of capsizing. The numerical simulations of water entry with various θ, wave heights H, and relative entry positions are carried out by combining large eddy simulation and overset mesh technology. The free surface is captured by the volume of fluid method, and the attitude change, acceleration change, motion trajectory, and free surface evolution law of lifeboats are analyzed. The findings suggest that lifeboats can enter calm water safely at θ of 20°–50° and maintain a stable posture. Moreover, in extreme conditions where θ is either 0° or 90°, there is a high risk of entry failure due to excessive vertical acceleration and poor motion attitude, respectively. Furthermore, when facing waves, lifeboats experience reduced horizontal displacement when entering at peak and downward zero point compared to calm water conditions, which poses challenges for avoiding potential dangers.

SPH simulations of complex 3D fluid–solid interactions with an improved single-layer particle boundary technique preventing boundary penetration

The smoothed particle hydrodynamics (SPH) method has been widely used to simulate fluid–solid interaction (FSI) problems. The solid boundary treatment under complex geometric configurations has always been a hot topic in the SPH numerical simulation. An improved single-layer particle technique combined with an effective anti-penetration boundary improvement algorithm is proposed in this paper, which allows for multi-resolution single-layer particle distribution and effectively prevents particle penetration under complex geometric configurations. Four engineering problems are simulated with the improved technique: dam-break flows with a rectangular prism, water entry of a revolution body, oscillations of a floating body, and gearbox operation. The simulation results of four engineering problems are in good agreement with the reference results, which demonstrates that the improved single-layer particle boundary technique proposed in this paper can accurately simulate the FSI problem of complex geometric configurations.