Article
Mechanics
Wangxia Wu, Qingquan Liu, Bing Wang
Summary: The study numerically investigates high-speed droplet impingement on typical curved surfaces to analyze complex wave structures and cavitation. The analysis includes the evolution of confined shock waves, cavities, and pressure distribution on concave, convex, and flat surfaces, showing different impacts on shock wave strength and cavitation behavior.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Mechanical
Amartya Jana, Lokanna Hoskoti, Mahesh M. Sucheendran
Summary: This study presents an analysis of the numerical study on underwater high-speed gas jets. The behavior and performance of the gas jets submerged in water are investigated under different operating conditions. Computational fluid dynamics is used to solve the unsteady Reynolds-averaged Navier-Stokes equations in a two-dimensional axisymmetric domain, and the effects of density difference between the gas and water are studied through comparative analysis.
JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME
(2022)
Article
Engineering, Marine
Yohan Choe, Chongam Kim
Summary: This study investigates the computational exploration of ventilated supercavitating flows around a high-speed underwater vehicle and its hydrodynamic characteristics. The results show that the presence of natural and ventilated cavitations and their interaction result in substantial nonlinear characteristics in cavity shapes and hydrodynamic forces.
Article
Energy & Fuels
Onur Baran, Ioannis K. Karathanassis, Phoevos Koukouvinis, Joonsik Hwang, Lyle M. Pickett, David Spivey, Manolis Gavaises
Summary: The influence of additives inducing viscoelasticity in diesel fuel on in-nozzle cavitation evolution and spray morphology has been quantified using high-speed imaging techniques. The additives were found to suppress wall-attached cavitation and enhance longitudinal vortices, leading to increased cone angles of the expelled spray. They also suppressed turbulence-induced transient instabilities.
Article
Mechanics
Zibo Ren, Huan Han, Hao Zeng, Chao Sun, Yoshiyuki Tagawa, Zhigang Zuo, Shuhong Liu
Summary: This study investigates the interactions between a cavitation bubble and a hemispherical pendant oil droplet immersed in water, both experimentally and theoretically. Four typical interactions are observed in experiments, and theoretical models are proposed to calculate the migration of the bubble centroid at the end of the collapse.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Hendrik Reese, Robin Schaedel, Fabian Reuter, Claus-Dieter Ohl
Summary: This study investigates the directed jet flow generated by a cavitation bubble near a rigid boundary, which acts as a pump to transport liquid through a perforated plate. The transport process is complex and dependent on various factors, such as the geometry of the bubble and connecting channel, liquid viscosity, and stand-off distance of the bubble to the plate. The results show that the flow rate and velocity of the jet are influenced by these factors. Additionally, different types of jet flow, such as needle jet and reverse jet, are observed under different conditions.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Emil-Alexandru Brujan, A-M Zhang, Yun-Long Liu, Toshiyuki Ogasawara, Hiroyuki Takahira
Summary: The jetting behavior and migratory characteristics of a laser-induced cavitation bubble in a rectangular channel were investigated experimentally and numerically. The study revealed various aspects of the bubble dynamics, such as the formation of liquid jets, bubble displacement, and interaction with the channel walls. Numerical simulations showed that liquid jets can reach velocities up to 100 m/s, and the bubble displacement in contact with the sidewalls of the channel can be as much as 350 μm.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Mandeep Saini, Erwan Tanne, Michel Arrigoni, Stephane Zaleski, Daniel Fuster
Summary: This work reveals that the response of a spherical cap bubble in contact with a rigid wall is influenced by the effective contact angle before collapse. The findings distinguish between two regimes with significantly different mechanisms of interaction between the collapsing bubble and its surrounding medium. The results have potential applications in various fields including geophysical flows and biomedical applications.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Dmitri Maklakov, Anna Lexina
Summary: In this paper, the free streamline problem of two-dimensional re-entrant jet cavity flow past an obstacle is investigated. It is shown numerically and analytically that the direction of the jet should be chosen almost opposite to the incident flow, and in the limiting configurations, the re-entrant jet vanishes and a free-surface flow with a symmetric bubble and two stagnation points is formed.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Juan Manuel Rossello, Hendrik Reese, Claus-Dieter Ohl
Summary: By focusing a laser near a liquid's free surface, two opposing jets can be created, with the downward jet having a longer lifetime and aligning perpendicular to the free surface. This phenomenon has potential applications in small droplets or shallow liquids.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Metallurgy & Metallurgical Engineering
Xin Wang, Ting-Qiang Xie
Summary: The study investigates cavitation erosion behavior of hydraulic concrete under high-speed flow by simulating strong cavitation using a high-speed and high-pressure venturi cavitation erosion generator. The collapse of cavitation bubble group produces high frequency, continuous, and unsteady pulse load on concrete walls, leading to fatigue failure. The downstream pressure significantly affects the cavitation action position and the main frequency of impact load, showing a power exponential relationship between cavitation load, cavitation erosion, and flow speed. Additionally, the degree of damage caused by cavitation erosion is approximately linearly reduced with an increase in concrete strength.
ANTI-CORROSION METHODS AND MATERIALS
(2022)
Article
Mechanics
Yongjiu Wang, Chenguang Huang, Tezhuan Du, Renfang Huang, Yuchang Zhi, Yiwei Wang, Zhijian Xiao, Zhendong Bian
Summary: This study numerically simulated the flow structures and hydrodynamic performance of high-speed surface-piercing hydrofoils, focusing on the interaction mechanism between supercavitation and natural ventilation. The results showed that hydrofoils with blunt trailing edges were more conducive to flow separation, and increasing the angle of attack led to higher ventilation rates. The hydrodynamic coefficients remained relatively stable in natural supercavitation, while they decreased by half when the supercavitation was fully ventilated.
Article
Engineering, Mechanical
Zhengwei Li, Zhiwu Xu, Peng He, Zhongwei Ma, Shu Chen, Jiuchun Yan
Summary: The characteristics of cavitation bubbles during the spreading of eutectic GaIn liquid droplet subjected to ultrasonication were studied in-situ by high-speed photography. It was found that the bubble density decreases gradually during the droplet spreading process and cavitation exhibits strong/weak changes with a periodicity of dozens of acoustic periods.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Chemistry, Multidisciplinary
Mahmoud Abd El-Aziz Mohamed, Hesham El-sayed Abdel Hameed, Ramy Elsayed Shaltout, Hafez Abdel Aal El-Salmawy
Summary: The study focused on the formation and development of cavitation inside nozzles of atomizers with different geometrical characteristics. It was found that the occurrence of cavitation depends on energy needed to overcome viscosity and friction, with mass flow decreasing as cavitation increases. The intensity of cavitation is influenced by the shape of the nozzle entrance.
Article
Mechanics
Xiao Hu, Aimee S. Morgans
Summary: This paper investigates the impact of unsteady wind loading on high-rise buildings and proposes two feedback control strategies to mitigate aerodynamic side-force fluctuations. The study shows that a linear controller exhibits better performance by delaying the formation of dominant vortices. Additionally, comparable control effect can be achieved by using a smaller sensing area.
JOURNAL OF FLUID MECHANICS
(2022)
Review
Chemistry, Physical
Ivan U. Vakarelski, Fan Yang, Sigurdur T. Thoroddsen
Summary: The outcome of bubble collision is determined by hydrodynamic interaction forces, influenced by the tangential mobility of gas-liquid interfaces. Bubbles with mobile surfaces coalesce easier due to lower hydrodynamic resistance, resulting in stronger rebound from a mobile liquid interface with lower viscous dissipation.
CURRENT OPINION IN COLLOID & INTERFACE SCIENCE
(2022)
Article
Energy & Fuels
Yuan Si Tian, Zi Qiang Yang, Sigurbur T. Thoroddsen, Ehab Elsaadawy
Summary: The separation of water droplets from water-in-crude-oil emulsions is crucial in the petroleum industry. A new experimental method involving optical-access flow, Near-Infrared laser illumination, and high-speed video imaging can help select the optimal demulsifier concentration by quantifying coalescence probability.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Chemistry, Multidisciplinary
Ivan U. Vakarelski, Kenneth R. Langley, Fan Yang, Sigurdur T. Thoroddsen
Summary: This study examines the accuracy of numerical simulations in predicting the dynamics of thin liquid film drainage during the collision of bubbles or droplets. Experimental investigations of millimetric bubbles colliding with a flat glass interface in pure water were compared with numerical simulations using the open source Gerris flow solver. The simulation results showed excellent agreement with experimental observations in terms of the bounce trajectory and thin liquid film profile. The study highlights the potential of numerical simulations in resolving the complex processes of high velocity bubble and droplet collisions.
Article
Engineering, Chemical
Yuan Si Tian, Er Qiang Li, Ehab Elsaadawy, Jia Ming Zhang, Ivan U. Vakarelski, Sigurdur T. Thoroddsen
Summary: In this study, microfluidic techniques were used to investigate the coalescence dynamics of water-in-oil emulsions in a simple shear flow. Experimental results showed a strong correlation between the coalescence time and the droplet approach velocity, effective diameter, offset, and continuous-phase viscosity. A scaling law for the dimensionless time needed for coalescence was also revealed.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Chemistry, Physical
Ivan U. Vakarelski, Farrukh Kamoliddinov, Sigurdur T. Thoroddsen
Summary: This study investigates the interaction between millimeter-sized bubbles and the seawater-air interface in seawater samples collected from the Red Sea coastal area. It demonstrates that high concentrations of electrolytes and organics in seawater do not affect the mobility of the bubble interfaces during free-rise and bouncing.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2022)
Article
Materials Science, Multidisciplinary
M. Jimenez-Valdez, E. Tomay, J. O. Marston, F. Pacheco-Vazquez
Summary: This study investigated the formation of doublet craters, which are created by binary projectiles impacting simultaneously at low speed on a sand bed. The morphology of the craters varied depending on the initial separation between the projectiles, including two well-defined craters, overlapping craters, or a single larger circular crater when the separation was negligible. The delay between impacts caused asymmetry in the ridge and ejecta curtains, with the delayed projectile penetrating deeper due to bed fluidization and material displacement from the first impact.
Article
Mechanics
Yuan Si Tian, Zi Qiang Yang, Sigurdur T. Thoroddsen
Summary: Fast microjets can be produced when drop-impact craters rebound or when a bubble bursts, and they play a crucial role in climate and olfactory senses as a source of aerosols. The most unique and fastest jets are generated when a small dimple forms at the crater bottom and rebounds without pinching off a small bubble. High-resolution numerical simulations reveal a new focusing mechanism that explains the extreme sensitivity to initial conditions observed in experiments of this phenomenon.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Materials Science, Multidisciplinary
Esraa Fakeih, Andres A. Aguirre-Pablo, Sigurdur T. Thoroddsen, Khaled N. Salama
Summary: This study investigates the design and fabrication of porous microneedles (MNs) and finds that injection through porous MNs results in a broader diffusion spread compared to hollow MNs. Three different designs of porous MNs with a constant pore size and controlled pore locations are fabricated using two-photon polymerization (2PP), and factors such as diffusion spread, mixing capabilities, and mechanical resilience are examined. The results show that porous MNs can cover 16 times the injection area of hollow MNs and demonstrate good mixing capabilities and mechanical strength.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Mechanics
Farrukh Kamoliddinov, Ivan U. Vakarelski, Sigurdur T. Thoroddsen, Tadd T. Truscott
Summary: In this experimental study, we investigated the hydrodynamics of a buoyant sphere accelerated along an air-water interface. The sphere displayed different behaviors depending on its speed, from floating on the surface to oscillating underwater and generating air cavities. These underwater air cavities were attached to the sphere surface near the laminar flow separation point. By changing the pulling angle and counterweight-induced velocity, we explored the effects on the hydrodynamics. Additionally, we analyzed the complex fluid-solid interactions and the influence of the air cavity on drag and lift coefficients and overall sphere hydrodynamics, particularly above the critical Froude number of 1.2.
Article
Chemistry, Physical
Zi Qiang Yang, Peng Zhang, Meng Shi, Ali Al Julaih, Himanshu Mishra, Enzo Di Fabrizio, Sigurdur T. Thoroddsen
Summary: Polymer filaments have important applications in biology, tissue engineering, and molecular machines. Researchers have developed a simple method to deposit stretched polymer fibers between micro-pillars, allowing for characterization of filament-forming configurations and their properties.
Article
Physics, Fluids & Plasmas
Ahmed Al Brahim, Sigurdur T. Thoroddsen
Summary: This study focuses on the dynamical rearrangement of a multilayer fluid in a Hele-Shaw cell, and observes various dynamics of stirring and breakthrough. The study reveals that air can break through a high viscosity layer and erupt as a hemisphere into a lower-viscosity layer, accompanied by high-speed airflow. Using high-speed video, the details of the eruptions and the key roles of wetting, contact lines, and three-dimensionality are characterized. Additionally, the study finds counterflows in the center-of-mass trajectories and the interchangeability of top and bottom layers through intermediate layers.