Water Splashing Research Articles

Water, mosquitoes, and sugar

Songkran, the new year and water splashing festival during 11-17 April, was the peak of road accidents in Thailand which now ranks number one in the world, COVID-19, and influenza. After Songkran was the World Malaria Day on 25 April. Thailand is striving to eliminate malaria as well as other mosquitoes-borne infectious diseases including Dengue fever and Zika virus. In addition to infectious diseases, Thailand is also facing with non-communicable diseases caused by excessive sugar consumption and smoking which currently appeared in a new form, the electronic version.

Experimental Investigation of Water Jet-Guided Laser Micro-Hole Drilling of Cf/SiC Composites.

In this paper, water jet-guided laser (WJGL) drilling of Cf/SiC composites was employed and the effects of the processing parameters on the depth and quality of the micro-holes were systematically investigated. Firstly, the depth measurement showed that the increase in processing time and power density led to a significant improvement in micro-hole drilling depth. However, the enhancement of the water jet speed resulted in a pronounced decrease in the depth due to the phenomenon of water splashing. In contrast, the scanning speed, path overlap ratio, pulse frequency, and helium pressure exhibited less effect on the micro-hole depth. Secondly, the microstructural analysis revealed that the increase in power density resulted in the deformation and fracture of the carbon fibers, while the augmentation in water jet speed reduced the thermal defects. Finally, based on the optimization of the processing parameters, a micro-hole of exceptional quality was achieved, with a depth-to-diameter ratio of 8.03 and a sidewall taper of 0.72°. This study can provide valuable guidance for WJGL micro-hole drilling of Cf/SiC composites.

Numerical Simulations of Seaplane Ditching on Calm Water and Uniform Water Current Coupled with Wind

In this paper, the ditching performance of a seaplane model on calm water and a uniform water current coupled with wind was numerically investigated. The overset grid technique was applied to treat the large amplitude of the body motions of the seaplane without leading to mesh distortion. The effects of the initial velocity and the initial pitch angle on the slamming loads and motion responses were investigated for the seaplane’s ditching on calm water. A good agreement with the experimental data on the velocity and angle was obtained. Besides ditching on calm water without the water current and wind, three more-complicated conditions were adopted, including the seaplane’s ditching on calm water with wind, a water current without wind, and a water current coupled with wind. The accelerations and impact pressures of the seaplane can be influenced by the wind or current. Water splashing and overwashing could be observed during the water entry process, with water overtopping the seaplane head or nose and flowing over the body surface. It can be concluded that the relative motion between the water and the seaplane model should be carefully controlled to avoid possible damages caused by the occurrence of overwashing.

Investigation on mechanism for water-gas jet-assisted laser processing of carbon fiber-reinforced polymer

Water-jet-assisted laser processing suffers from energy losses, while gas-assisted laser processing encounters insufficient cooling. To better address these issues, this paper proposes a method of water-gas jet-assisted laser processing for carbon fiber-reinforced polymer (CFRP) materials to explore the thermal damage control effect in laser processing of CFRP. The method of water-air jet-assisted laser processing involves the formation of a water layer by the impact of a water jet on the workpiece, followed by the addition of auxiliary gas above the water layer to impact it. This method effectively suppresses water splashing and debris interference, thus enhancing the quality of CFRP processing. The present research investigates the effects of air pressure, water pressure, gas jet-target distance, and gas nozzle diameter on CFRP processing quality through single-factor experiments, which are subsequently optimized using orthogonal experiments. Furthermore, a three-dimensional model for water-gas jet-assisted laser processing was established in this study, and the flow field was analyzed using computational fluid dynamics software, aiming to explore methods for optimizing the flow field. Experimental and simulation results demonstrate that the water-air jet-assisted laser processing technique ensures both the cooling effect of water and minimizes the impact of the water layer on the laser transmission path, thereby facilitating the achievement of thermal balance removal in CFRP.

China’s reopening border, AOCR2023 in Bangkok, and Songkran

After 3 years of absence due to COVID-19 pandemic, the first group of Chinese tourists from Xiamen arrived Bangkok, Thailand, on Monday 9th January 2023 just a day after China abandoned zero-COVID policies and reopened its border on Sunday 8th January. During 9th-12th February, the Royal College of Radiologists of Thailand (RCRT) and the Radiological Society of Thailand (RST) hosted the 21th Asian Oceanian Congress of Radiology (AOCR), 40 years after they last hosted the 4th AOCR in 1983. Leaders in Radiology from Asian Oceanian countries met and shared their experiences and opinions on various topics. This issue takes core messages from Asian Symposia in AOCR on tuberculosis and post COVID lung disease. In March, the missing caesium-137 in Thailand generated lots of fear and anxiety, fuelled by social media and inadequate statements from the authorities. The need of effective risk communication was discussed in this issue. Songkran, the water splashing festival which is Thailand’s traditional new year during 13th-15th April, marked the end of wearing masks and social distancing due to the pandemic as both local and visitors from around the world, as many as more than 100, 000, gathered in many famous parts of Thailand.

All-inorganic perovskite quantum dots-based electrospun polyacrylonitrile fiber for ultra-sensitive trace-recording

All-inorganic dual-phase CsPbBr3-Cs4PbBr6 quantum dots (CPB QDs)-based polyacrylonitrile (PAN) fiber synthesized by supersaturated recrystallization and electrospinning technique possesses characteristics of homogeneous morphology, high crystallinity and solution sensitivity. Under 365 nm laser excitation, CPB@PAN fiber exhibits surprising trace-recording capability attributing to the splash-enhanced fluorescence (FL) performance with a narrow-band emission at 477–515 nm. In the process of ethanol anhydrous (EA) and water splashing, the CPB@PAN fiber presents conspicuous blue and green emission when contacting with EA and water, and maintains intense blue and green FL for more than 4 months. These experimental and theoretical findings provide a facile technology for the development of biological protection display, biotic detection and moisture-proof forewarning based on the trace-recording performance of CPB@PAN fiber.

Experimental study of air velocity effect of heat transfer in distillation condenser

A cooling tower is a heat exchanger equipment that uses water splashing media to lower the temperature by extracting heat from the water and emitting it into the atmosphere. Wind speed or velocity of wind waves is a fundamental atmospheric quantity caused by moving air from high pressure to low pressure while wind is moving air. Air velocity has an effect on the value of heat transfer coefficient, the faster the air, the better the value so that the heat transfer that occurs is also better. Research was also carried out on the human body to see forced convection due to the movement of these parts of the body, resulting in that the faster the body moves, the better the heat transfer coefficient value, this is related to the air flow that occurs on the body surface. The test shows that the more blower rotation make faster the heat transfer that occurs. At 2500 RPM rotation shows higher heat transfer by producing an average of 29.210 watts, the displacement decreases when the rotation is lowered to 1700 RPM to produce an average of 20.677 watts. The effectiveness of the tool by increasing the rotation from 1700 to 2500 by 32%.

The development, implementation and challenges to water-saving practices in a water-stressed destination: a case study of the Songkran Festival, Thailand

PurposeThe contradiction between the purpose of the water-splashing tradition, the use of water in a water-stressed destination and overconsumption during a time of water shortage led the researchers to question the spirit of the Songkran Festival. It is important to keep the spirit of the festival alive without interrupting the livelihoods of the community and to critically engage with opportunities and challenges related to water-saving practices during the festival. Thus, this study aims to investigate the opportunities and challenges to responsible practices of water-saving at a cultural festival, using a case study of the water-splashing practice at the Songkran Festival in Thailand.Design/methodology/approachThis study used the cultural practice, namely, the water-splashing tradition at the Songkran Festival in Thailand, as a case study. The researchers conducted document analysis on local newspapers, the Bangkok Post specifically and participant observation at the Songkran Festival in the Khao San Road area in Bangkok, to gain first-hand insights to develop comprehensive results which answers the study’s objectives.FindingsThe key findings show three significant themes representing the opportunities for implementing sustainable water-saving practices; a call for a water-saving campaign, education on water saving and water-splashing restrictions. In terms of challenges to implementing water-saving practices, two key themes emerged; a lack of water stress and drought awareness and the hedonistic characteristic of water splashing. The study findings provide important implications to theory and practice for sustainable event management and provide considerations for event stakeholders to minimise water overuse in festivals.Originality/valueEnvironmental degradation is a key global issue that the United Nations addresses in the Sustainable Development Goals (SDGs) scheme (United Nations Development Program, 2016). According to Pereira et al. (2009), water scarcity can be caused by both human activities and natural causes. Factors such as unlimited water consumption, population growth and climate change are some of the contributing factors that not only affects resident's access to water but also on events hosted within communities. It is crucial that event managers critically re-think the way festivals are designed in water-stressed destinations.

A Review of Membrane-Facilitated Liquid-Solid Conversion: Adding Laser-Induced Breakdown Spectroscopy (LIBS) Multi-Applicability for Metal Analysis

Water splashing and evaporation are challenging aspects in Laser-Induced Breakdown Spectroscopy (LIBS) analysis when it comes to aqueous analyte. By converting the liquid sample into solid, among many other methods, one can improve the analytical performance of LIBS. Membrane is a type of material which can be used to facilitate liquid-solid conversion through various procedures; drop-wising, adsorption, filtration, and phase inversion. In a spotlight, ion exchange membrane allows LIBS technique to analyze the specific heavy metal ion species. This review article reports on advancement of membrane-facilitated liquid-solid conversion to enhance LIBS quantitative analysis of aqueous metals. Such method had been reported to generate low limit of detections (LODs), even up to sub µg/kg. The accuracy and precision produced by the reported methods were not significantly different to that obtained from conventional analytical techniques, such as Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). In conclusion, the use of membrane to convert the analyte can add the application of LIBS for multiple purposes with a satisfying analytical performance.

Scene Summarization via Motion Normalization.

When observing the visual world, temporal phenomena are ubiquitous: people walk, cars drive, rivers flow, clouds drift, and shadows elongate. Some of these, like water splashing and cloud motion, occur over time intervals that are either too short or too long for humans to easily observe. High-speed and timelapse videos provide a popular and compelling way to visualize these phenomena, but many real-world scenes exhibit motions occurring at a variety of rates. Once a framerate is chosen, phenomena at other rates are at best invisible, and at worst create distracting artifacts. In this article, we propose to automatically normalize the pixel-space speed of different motions in an input video to produce a seamless output with spatiotemporally varying framerate. To achieve this, we propose to analyze scenes at different timescales to isolate and analyze motions that occur at vastly different rates. Our method optionally allows a user to specify additional constraints according to artistic preferences. The motion normalized output provides a novel way to compactly visualize the changes occurring in a scene over a broad range of timescales.

Effect of wettability on droplet impact: Spreading and splashing

This study experimentally investigates the dynamic behaviors of water droplets over wide ranges of diameters and velocities (200 μm < D0 < 2600 μm, 50 < We < 3000) impacting on surfaces with various wettability (ranging from hydrophilic to superhydrophobic), and focuses on the effect of surface wettability on water droplet spreading and splashing. The experimental results show that the surface wettability contributes to the lift of the lamella, related to the cosine of the advancing angle (cosθa), that significantly influence the spreading and splashing. The lifting lamella promotes the spreading speed by reducing the surface friction and the viscous dissipation in the boundary layer. The mean spreading speed is linear to the impact velocity on each surface type, and the contact angle slightly affects the mean spreading velocity on the hydrophilic or hydrophobic surface. While, the mean spreading velocity on the superhydrophobic surface is much larger than the other surfaces due to the fewer viscous dissipation. The splashing behavior is dominated by the force from the air surrounding the lamella. The experimental results demonstrate that the splashing threshold K = OhRe1.25 is independent of the advancing angle for the case of θa < 90°, but is proportional to cosθa for the case θa > 90°. Furthermore, we put forward a prediction model of droplet splashing threshold, considering the effect of surface wettability, as K/K0 = 1 + αcosθa, which could quantitatively express the effect of surface wettability on water droplet splashing.

A Novel Design of Ergonomic Ablution Place at Mosques in Arar, Saudi Arabia

Currently, there are hardly any uniform design specifications for the construction of ablution places at mosques in Saudi Arabia. Designs of ablution places are usually copied from designs of ablution places in other mosques or based on individual perspectives. Based on the researchers’ anecdotal observations, most of these designs are nonergonomic, uncomfortable, and less user-friendly for ablution in either sitting or standing position, especially for the elderly. In such designs, water splashing is common because of inappropriate heights of platforms or seats, insufficient distances between seats and faucets, and improper shapes and depths of water drain. The purpose of the present study is to present the design of a novel ergonomic ablution place to ensure comfortable, safe, and hygienic conditions. The design is particularly related to the size and height of seat, height and distance of faucet from the seat, depth and slope of water drain, and height and width of the platform. The design was implemented at four mosques in Arar, Saudi Arabia. Modifications at ablution places were made according to the proposed design and were appreciated by the local community. The design was communicated to the Directorate of Mosques in Arar and agreed upon for implementation in other mosques.

Similarities and Differences between Performers and Observers in Processing Auditory Action Consequences: Evidence from Simultaneous EEG Acquisition.

In our social environment, we easily distinguish stimuli caused by our own actions (e.g., water splashing when I fill my glass) from stimuli that have an external source (e.g., water splashing in a fountain). Accumulating evidence suggests that processing the auditory consequences of self-performed actions elicits N1 and P2 ERPs of reduced amplitude compared to physically identical but externally generated sounds, with such reductions being ascribed to neural predictive mechanisms. It is unexplored, however, whether the sensory processing of action outcomes is similarly modulated by action observation (e.g., water splashing when I observe you filling my glass). We tested 40 healthy participants by applying a methodological approach for the simultaneous EEG recording of two persons: An observer observed button presses executed by a performer in real time. For the performers, we replicated previous findings of a reduced N1 amplitude for self- versus externally generated sounds. This pattern differed significantly from the one in observers, whose N1 for sounds generated by observed button presses was not attenuated. In turn, the P2 amplitude was reduced for processing action- versus externally generated sounds for both performers and observers. These findings show that both action performance and observation affect the processing of action-generated sounds. There are, however, important differences between the two in the timing of the effects, probably related to differences in the predictability of the actions and thus also the associated stimuli. We discuss how these differences might contribute to recognizing the stimulus as caused by self versus others.

Visual and passive acoustic observations of blue whale trios from two distinct populations

Visual and passive acoustic observations of blue whale trios from two distinct populations

Analysis of fluid-particle interaction in granular materials using coupled SPH-DEM method

ABSTRACT In this study, based on Smoothed Particle Hydrodynamics (SPH) and Discrete Element Method (DEM), a multiphase fluid-solid coupling algorithm of SPH-DEM is provided, and a high performance coupling module is developed based on two open-source software platforms, namely: DualSphysics for SPH and Blaze-DEM for DEM. With a comparative analysis of three typical tests, it is systematically proved that the developed coupling module can feasibly and precisely tackle the complex coupling between solid particles and fluid. Moreover, based on the test results of single particle sedimentation and water-entry of spinning spheres, three water-entry stages of the spheres are characterized: contact and shockwave generation, cavity formation and water splashing, and cavity closure and collapse. As a complex problem, the submerged granular collapse is simulated, and according to the numerical results the process of granular collapse can be divided into four stages: beginning, collapsing, decelerated sliding and stable sedimentation. The granular aggregation can be partitioned into the zones of flowing, sliding, shearing, and relatively standstill particles by the motion characteristics of different parts of particles on different stages. In addition, the macro- and meso-characteristics of the process of granular collapse are also discussed. According to the research results of this study, the developed SPH-DEM module can better simulate the complex coupling process between fluid and granular materials. Furthermore, with more information obtainable, numerical simulation is important to get insight into this process.

Numerical investigation of the jet velocity profile and its influence on the Pelton turbine performance

Numerical investigation of the unsteady flow patterns around the bucket can be helpful to improve the Pelton turbine efficiency. In fact, by studying the loss mechanisms in the flow, one can optimize the bucket design. For this purpose, an accurate investigation of the water jet is also necessary as an inlet condition for the bucket flow. The water jet ejected from the nozzle is actually non-uniform, due to the upstream turbulence and secondary flow in the distributor, bending pipes, needle and supports. This non-uniformity causes a deviation of the water jet from the ideal jet center, which is tangent to the jet circle, and it directly affects the flow patterns around the bucket. Whereas water splashing makes experimental observations very challenging, a numerical approach is effective and convenient to study the unsteady flow pattern in a Pelton turbine. In the present research, numerical analysis of the two-phase flow through the distributor, bending pipe and nozzle, has been performed. The jet velocity profile has been verified with experimental results, which are measured in the model test equipment, and good agreement is obtained for both velocity profile and jet deviation. In addition, the analysis of the bucket unsteady flow is performed using the aforementioned non-uniform jet velocity profile and the calculated flow pattern around the bucket is compared to the previous calculation using a uniform velocity profile at the inlet boundary. The difference between the two cases is discussed based on the quantitative and qualitative evaluation from the numerical analysis.

Numerical study on the characteristics of single wetted flat wire with single droplet impact under the disturbance of airflow

In this paper, the dynamic process of droplet impacting on the wire is carried out. The CLSVOF method is used to simulate the single droplet impacting on the wet flat wire under the disturbance of airflow. After reasonable simplification, the two-dimensional mathematical model of the wire surface is established, which is used to analyze the influence of droplet diameter and initial velocity on droplet impact behavior. The characteristics of liquid film morphology, internal pressure field and velocity field during droplet impacting are studied, and combined with the re-entrainment in the mesh separator, the cause of droplet breakup is discussed. The numerical results show that the motion pattern of the liquid film after the droplet impacting on the wet wire can be divided into water waveform motion, crown motion and splashing motion which are determined by droplet diameter and initial velocity; At the beginning of the impact on the wet wire, the neck bulge at the contact point between the droplet and the surface film is caused by a large pressure drop in the neck region. The analysis of the velocity field verifies the kinematic discontinuity theory.

Effects of Fire on the Strength of Reinforced Concrete Structural Members

This multidisciplinary research focuses on the effect of fire on structures due to the Boko Haram insurgency in Maiduguri, Northern Nigeria. It is aimed at giving a further contribution to understand the effect of fire with respect to the local aggregates, quenching methods and proposing an assessment methodology based on a suitable analytical procedure applied to reinforced concrete subjected to sustained fire. Cement, river sand, Bama gravel and water in standard proportion in accordance to BS1881 Part 101 were mixed to produce beams, slabs and cubes of different sizes and cured for 28 days. The samples were burnt in a designed fire simulation furnace using sugarcane bagasse as fuel with varying air velocities for 2 hours. Cooling of samples was carried out using water splashing, CO2 powder fire extinguisher and air cooling methods before the compressive strength tests using a Seidner Compressive Testing Machine and Non-destructive test with Rebound Hammer. The scanning electron microscopy tests were carried out using a Phenom ProX scanning electron microscope for imaging and analysis to physically examine and determine the elemental micro structural redistribution and influence on the tested samples. As the temperature within the experimental set-up reaches 900°C, the temperature around the vicinity of slab, beam or cube reached an average of 500°C. The results of the investigations show that different cooling methods induce varying levels of deteriorating and significant effects on the final internal micro-structures as well as physical, mechanical and thermal characteristics of concrete. Results from the destructive and non-destructive tests show that losses of strength vary from a minimum of 37.73% to a maximum of 86.67 % in the samples investigated. The local aggregates used namely the river sand and the Bama gravel surely influenced the medium grade reinforced concrete behaviour when subjected to fire.

SIMULATION ANALYSIS ON CHARACTERISTICS OF SINGLE DROPLET IMPACT ON MESH BASED ON CLSVOF METHOD

In this paper, the dynamic process of droplet impacting on the mesh is carried out. The CLSVOF method is used to simulate the single droplet impacting on the wet flat mesh under the disturbance of airflow. After reasonable simplification, the two-dimensional mathematical model of the mesh surface is established，which is used to analyze the influence of droplet diameter and initial velocity on droplet impact behavior. The characteristics of liquid film morphology, internal pressure field and velocity field during droplet impacting are studied, and combined with the re-entrainment in the mesh separator, the cause of droplet breakup is discussed. The numerical results show that the motion pattern of the liquid film after the droplet impacting on the wet mesh can be divided into water waveform motion, crown motion and splashing motion which are determined by droplet diameter and initial velocity; At the beginning of the impact on the wet mesh, the neck bulge at the contact point between the droplet and the surface film is caused by a large pressure drop in the neck region. The analysis of the velocity field verifies the kinematic discontinuity theory.

Simulation of a laboratory-scale experiment for wave propagation and interaction with a structure of undersea topography near a nuclear power plant using a divergence-free SPH

The Divergence-Free SPH (DFSPH) method is a recently proposed novel incompressible Smoothed Particle Hydrodynamics (SPH) method. The DFSPH method enforces incompressibility via two iterative solvers: the Divergence-Free (DF) solver and the Constant-Density (CD) solver. In this study, the DFSPH algorithm is implemented into the SOPHIA Plus framework to simulate a set of wave propagation under the same geometry and conditions of a laboratory-scale experiment. The experiments are conducted for wave propagation and interaction with a structure of scaled-down undersea topography near the Kori nuclear power plant in South Korea. This study compares the free surface propagation and the wave height with the experimental measurements for three test cases: low/medium/high frequency waves. Overall, the simulation shows good agreement with the experiment both qualitatively and quantitatively. However, according to the sensitivity study, more realistic water splashing behaviors are captured as the particle size is reduced. The predicted wave heights at three different locations are also in fairly good agreement with the experimental measurement. Slight differences are observed after the wave collides with the structure because of the low energy dissipation in the simulation. However, the differences are not significant.