Article
Mechanics
Alessio Innocenti, Alice Jaccod, Stephane Popinet, Sergio Chibbaro
Summary: The study investigates bubble-induced turbulence through numerical simulations, comparing results with experiments and previous simulations to assess the accuracy of the model. Analysis reveals that the energy transfer mechanisms and potential cascades are unveiled through a local scale-by-scale analysis in physical space.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Chemistry, Physical
Jiaojiao Wang, Yanzhong Li, Lei Wang, Siqi Xia, Jianhua Ren, Hongwei Mao, Yuanyuan Xu
Summary: Understanding bubble dynamics and heat transfer characteristics of hydrogen boiling in microgravity is essential for safe and efficient use of liquid hydrogen in space. The study developed a numerical simulation model to predict the subcooled pool film boiling for liquid hydrogen in different gravities, revealing that poor heat transfer performance is observed in reduced gravity and bubbles may grow larger with decreasing gravity.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2021)
Article
Mechanics
Niklas Hidman, Henrik Strom, Srdjan Sasic, Gaetano Sardina
Summary: Using direct numerical simulations (DNS), a transition in the scalar spectra from k(-5/3) to k(-3) scaling with wavenumber k is observed in bubbly flows with passive scalars. The decay of the scalar spectrum is faster than k-3 at high wavenumbers for cases with a mean scalar gradient in the horizontal direction. DNS computations reveal that scalar fluctuations are produced by the mean scalar gradient at length scales above the bubble diameter, leading to the k(-3) scaling of the scalar spectra.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Engineering, Environmental
Sijie Dong, Di Wei, Yuchao Cai, Bo Wang, Teng Cheng, Yumeng Zhang
Summary: This paper investigates the performance of a vortex-broken electrocyclone under different inlet velocities and working voltages through experiments and numerical simulations. The experimental results show that the vortex-broken electrocyclone can simultaneously reduce pressure drop and improve collection efficiency. However, at high inlet velocities, the decrease in pressure drop is more significant, while the increase in collection efficiency is the opposite.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Engineering, Marine
Trong-Nguyen Duy, Thanh-Hoang Phan, Quang-Thai Nguyen, Seong-Ho Park, Warn-Gyu Park
Summary: This study investigates bubble dynamics with highly nonlinear interactions between an oscillating bubble and gas-liquid interface in the vicinity of a rigid wall with a gas-entrapping hole through numerical simulations. The simulations show that the gas entrapped inside the hole significantly affects the formation and redirection of the liquid jet, as well as the dynamics of the cavitation bubble.
Article
Mechanics
F. Le Roy De Bonneville, R. Zamansky, F. Risso, A. Boulin, J. -f. Haquet
Summary: This study presents a numerical method for simulating the flow induced by bubbles rising at large Reynolds numbers and accurately estimates the hydrodynamic force exerted by the liquid on the bubbles. The simulations show good agreement with experimental results, indicating potential applications in studying industrial bubble columns and large-scale systems.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Thermodynamics
Hatim Machrafi, Pierre Dauby
Summary: This study develops a comprehensive axisymmetric transient model to describe the injection and evaporation process of a sessile droplet. The model is validated against experimental data in both Earth and microgravity conditions. It is found that the injected volume affects the evaporation rate, but its influence is weaker under microgravity conditions compared to Earth conditions. It is also revealed that uncertainties involving the injection are not an obstacle to model the evaporation of sessile droplets in most cases.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Acoustics
Kalman Klapcsik, Ferenc Hegedus
Summary: This study compares the accuracies of two numerical approaches used to model the translational motion of an acoustic cavitational bubble in a standing acoustic field. The first approach decouples the equation of translational motion from the radial oscillation, while the second approach solves the coupled ordinary differential equations directly. Results show that both models can reveal stable equilibrium positions, but the time-resolved approach provides more accurate results in oscillatory solutions where transient behavior is important.
ULTRASONICS SONOCHEMISTRY
(2023)
Article
Mechanics
Mehran Soleimani, Ali Ahmadpour, Ehsan Amani
Summary: In this study, three-dimensional numerical simulations were conducted to investigate the impact of direct current electric fields on subcooled flow boiling heat transfer in a vertical minichannel. The volume of fluid model was used to represent the liquid-vapor interfaces, and the conservation laws and electrohydrodynamic equations were solved using the finite volume method. Two mass transfer models were evaluated, and a new seeding algorithm was developed based on the physics of bubble formation and departure on heated walls, integrated with the Fourier model. The numerical results showed an early transition from slug to churn/annular flow regimes due to EHD forces, in agreement with experimental observations.
Article
Mechanics
Felix Huber, Anna Garcia-Sabate, Dominique Legendre, Ricard Gonzalez-Cinca
Summary: The numerical investigation focuses on the translational motion of gas bubbles immersed in a liquid subjected to an acoustic wave at different gravity levels. The study discusses the dynamics of bubbles at different gravity levels and proposes an analytical criterion for the capture of bubbles in a levitation position. This criterion is based on the balance between the average acoustic force and the buoyancy force, allowing the calculation of the bubble levitation position for any scenario.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2021)
Article
Mechanics
J. M. Bermudez-Graterol, R. Skoda
Summary: This study presents a mathematical model for simulating spherical bubble dynamics in binary alkane mixtures. The model resolves detailed heat and mass transfer, phase transition, air absorption and desorption. It is found that the low-volatile component exhibits counter-intuitive mass transport opposite to diffusion flux, and the local segregation of mixture components affects the growth rate of bubbles, especially in low heptane mixtures.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Darshan Patel, S. Vengadesan
Summary: This study investigates the behavior of bubble ascent under the influence of an applied electric field. A numerical model is developed to accurately calculate charge distribution and Coulomb force, and is used to study the effects of electric capillary number, electrical conductivity ratio, and permittivity ratio. The study finds that the presence of an electric field induces vortices near the bubble, which interact with the bubble's motion and result in various phenomena.
Article
Mechanics
Wei Liu, Ning Li, Chun-sheng Weng, Xiao-long Huang, Yang Kang
Summary: An underwater detonation tube experiment was conducted to investigate the bubble dynamics and pressure field characteristics of an underwater detonation gas jet. The experiment revealed four stages of jet process and demonstrated the potential feasibility of generating pulsation bubbles with underwater detonation gas jets.
Article
Mechanics
R. T. Cerbus, H. Chraibi, M. Tondusson, S. Petit, D. Soto, R. Devillard, J. P. Delville, H. Kellay
Summary: The generation of liquid jets and drops near a liquid-air interface using femtosecond laser pulses involves the nucleation of cavitation bubbles and the emergence of two distinct jets. The first jet is thin and fast, produced during the initial expansion of the bubble, while the second jet is thick and slow, emanating from the surface as the bubble deflates. The mechanism behind this phenomenon has been investigated using experiments and simulations, revealing that the second jet is not a result of bubble expansion but originates from the secondary flows induced by the bubble dynamics. A phase diagram has been established to understand the emergence of the second jet by linking its properties to the control parameters of the problem.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Engineering, Multidisciplinary
Chanwoo Kim, Hyun Sun Park, Hang Jin Jo, Moohwan Kim
Summary: This study investigates energy dissipation through shock-bubble interaction (SBI). A developed SBI model is used to obtain the propagation of shockwaves in a bubbly mixture and the dissipation of shock energy during bubble oscillation. The dissipation power is estimated by evaluating the concepts of dissipation energy (DE) and damping time (DT).
ALEXANDRIA ENGINEERING JOURNAL
(2022)
Article
Engineering, Chemical
Devy Setiorini Sa'adiyah, Kosuke Hayashi, Ryo Kurimoto, Akio Tomiyama
Summary: The experiments investigated CO2-water bubble flows in a vertical pipe, focusing on the spatial evolution of the flows with different impurities. The numerical predictions of the flow patterns transitioning from bubbly to slug flow depending on the impurities agreed well with the experimental results.
CHEMIE INGENIEUR TECHNIK
(2021)
Article
Nuclear Science & Technology
Toshiya Takaki, Raito Goda, Kosuke Hayashi, Michio Murase, Akio Tomiyama
Summary: The study compared flow characteristics in vertical pipes of diameters 20 mm and 40 mm, revealing differences in CCFL characteristics and the transition from smooth film to rough film between the two. However, the correlation between film thickness and wall friction factor for the smooth film was similar in pipes of different diameters.
NUCLEAR ENGINEERING AND DESIGN
(2021)
Article
Nuclear Science & Technology
Raito Goda, Ryo Kurimoto, Kosuke Hayashi, Michio Murase, Akio Tomiyama
Summary: A study investigated the effect of liquid viscosity on gas-liquid counter current flow in a vertical pipe, proposing correlations for interfacial and wall friction factors. Experimental results showed flow classified into two regimes, with interfacial friction factor dependent on inertial and buoyant forces balance. Wall friction factor correlated with liquid Froude number, Reynolds number and dimensionless pipe diameter within specific ranges.
NUCLEAR ENGINEERING AND DESIGN
(2021)
Article
Clinical Neurology
Hidehito Kimura, Susumu Osaki, Kosuke Hayashi, Masaaki Taniguchi, Yuichi Fujita, Takeshi Seta, Akio Tomiyama, Takashi Sasayama, Eiji Kohmura
Summary: This study investigated the prediction of thin-walled regions (TIWRs) in intracranial aneurysms, finding that the oscillatory shear index (OSI) may be a unique predictor for TIWRs, with low OSI strongly corresponding to TIWRs. Receiver operating characteristic curve analysis showed that OSI was the most effective hemodynamic parameter, followed by time-averaged wall shear stress (TAWSS).
WORLD NEUROSURGERY
(2021)
Article
Engineering, Chemical
Devy Setiorini Sa'adiyah, Yuki Matsuo, Michael Schlueter, Ryo Kurimoto, Kosuke Hayashi, Akio Tomiyama
Summary: In this study, mass transfer rates of single carbon-dioxide bubbles with chemical absorption in a vertical pipe using aqueous sodium hydroxide solutions were investigated. The enhancement factor E was found to be related to pH and bubble diameter, and a correlation for E was developed. By combining this correlation with Sherwood number correlations, accurate estimation of Sherwood number for bubbles with chemical absorption was achieved. Additionally, the applicability of the correlations to bubbles in a larger pipe diameter was examined.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Nuclear Science & Technology
Toshiya Takaki, Michio Murase, Kosuke Hayashi, Akio Tomiyama
Summary: The objective of this study was to reduce uncertainties in correlations for flow characteristics in vertical pipes under top end flooding. The study focused on evaluating liquid film thickness and interfacial friction factor using derived correlations and existing data, with consideration for different pipe diameters and pressures. Results showed that the derived correlations were applicable to various conditions and modifications were made based on computed values. Additionally, drift-flux parameters for smooth film were also considered.
NUCLEAR TECHNOLOGY
(2022)
Editorial Material
Clinical Neurology
Hidehito Kimura, Kosuke Hayashi, Susumu Osaki, Ayaka Shibano, Yuichi Fujita, Hiroaki Nagashima, Akio Tomiyama, Takashi Sasayama
WORLD NEUROSURGERY
(2022)
Article
Mechanics
Rina Nakajima, Kosuke Hayashi
Summary: Experiments were conducted to study the behavior of liquid drops falling through a miscible liquid. It was observed that the drops deform into vortex rings and fragment into smaller drops due to the Rayleigh-Taylor instability. The number of smaller drops was measured for different Archimedes numbers, and the influence of vortex ring interactions on fragmentation was analyzed.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Thermodynamics
Ryo Kurimoto, Yuji Takeuchi, Hisato Minagawa, Takahiro Yasuda
Summary: The axial development of the base film thickness of an upward air-water annular flow after passing through a 90 degrees bend was investigated. The study measured the base film thickness and axial velocity at different positions and bend curvatures, and analyzed the symmetry of their circumferential distributions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2022)
Article
Nuclear Science & Technology
Ryoya Koto, Ryo Kurimoto, Atsuya Imaizumi, Kosuke Hayashi, Akio Tomiyama
Summary: This study measured the interfacial and wall friction factors of air-water swirling annular flows in a vertical pipe and introduced an interfacial swirl number as an indicator of swirl intensity. The results showed that the interfacial swirl number varied with axial distance and had a correlation with the friction factors. The three-fluid model was found to be more appropriate for evaluating the friction factors in swirling annular flows compared to the two-fluid model.
NUCLEAR ENGINEERING AND DESIGN
(2022)
Article
Mechanics
Mattia Bucci, Matevz Zupancic, Alekos Ioannis Garivalis, Axel Sielaff, Paolo Di Marco, Iztok Golobic
Summary: In this study, the effects of electric fields on bubble departure dynamics during pool boiling were investigated in microgravity conditions. The results showed that the process of bubble departure from the wall begins before the electric stresses start to pull the bubble up. The study provides important insights into the behavior of bubbles on heated surfaces in the presence of electric fields.
Article
Thermodynamics
Kosuke Hayashi, Shosuke Yasui, Ryo Kurimoto, Akio Tomiyama
Summary: Experiments were conducted to investigate the effects of pipe bending on the void fraction in air-water two-phase flows through a horizontal U-bend in the vertical plane. The void fractions in the bend and straight sections were measured using quick-closing valves and evaluated through image processing. The study also discussed the applicability of existing correlations for void fraction in straight pipes and found better agreement with data for specific flow regimes.
HEAT TRANSFER ENGINEERING
(2023)
Article
Physics, Fluids & Plasmas
Kosuke Hayashi, Yuya Motoki, Matheus J. A. van der Linden, Niels G. Deen, Shigeo Hosokawa, Akio Tomiyama
Summary: This study conducts numerical simulations of the behavior of contaminated spherical drops falling through a stagnant liquid at low Reynolds numbers using the finite difference method. The results show that the surfactant concentrations vary significantly with different angles, and the high-pressure spots prevent fluid motion, leading to a decrease in interfacial surfactant concentration. The study highlights the importance of understanding the effects of surfactants on fluid motions in such systems.
Article
Thermodynamics
Cong Li, Jiali Wang, Chenhui Wang, Yanke Jin, Yina Yao, Rui Yang
Summary: This study investigates the impact of NaCl water droplets with various concentrations on a heated surface. The results show that the impact patterns can be categorized into different types, and models are established to predict the spreading behavior of droplets with different concentrations. Additionally, high concentration droplets exhibit more violent boiling and have lower residual energy and rebound time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
C. Barrera, V. Castro, F. Escudero, J. J. Cruz, I. Verdugo, J. Yon, A. Fuentes
Summary: This study focuses on the characterization of soot maturity and sooting propensity of anisole fuel in a controlled laminar coflow diffusion flame. The results show that the spatial distribution of soot volume fraction is enhanced near the flame centerline, while soot production is promoted near the flame wings. The temperature increase also affects the maturity of soot particles.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Roman W. Morse, Jason Chan, Tiago A. Moreira, Jared J. Valois, Evan T. Hurlburt, Jean-Marie Le Corre, Arganthael Berson, Kristofer M. Dressler, Gregory F. Nellis
Summary: This study investigates the dryout of liquid film and the role of disturbance wave frequency. Experimental results indicate that the heat transfer coefficient associated with optimal boiling conditions is maximized when the surface is dry 5% of the time, independent of pulse amplitude and frequency. Liquid-film measurements, dryout statistics, and direct observation suggest that disturbance-wave frequency can be manipulated by density-wave oscillations in the flow field.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
E. J. Vega, J. M. Montanero
Summary: In this study, we experimentally investigated the bursting of a bubble covered with a surfactant. We found that the bubble bursting time is longer compared to a surfactant-free bubble due to interfacial elasticity. Furthermore, the Marangoni stress drives liquid flow that allows the jet to escape from the end-pinching mechanism within a certain surfactant concentration range.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Guofu Sun, Yi Zhan, Tomio Okawa, Mitsuhiro Aoyagi, Akihiro Uchibori, Yasushi Okano
Summary: Experiments were conducted on liquid jets ejected from oval nozzles to investigate the effects of nozzle orifice shape on jet behavior. The study found that the liquid jet exhibited different characteristics at different liquid flow rates. Correlations were established to predict the liquid jet state and characteristics of the secondary droplets produced during jet impact onto a solid surface. This research extended the available knowledge on liquid jet behavior.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Jeonghoon Lee, Laurent Zimmer, Takeshi Saito, Shinji Nakaya, Mitsuhiro Tsue
Summary: This study investigates the effects of spatial resolution on DMD amplitudes and spatial mode strengths, and proposes scaling factors to correct for the resolution differences. The results show that the proposed scaling factors successfully normalize the amplitudes and spatial modes, allowing for quantitative comparison of data obtained with different spatial resolutions. This study is significant for analyzing spatiotemporal data in various fields.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yanli Zhao, Shibing Kuang, Xiaoliang Zhang, Mingjun Xu
Summary: This study experimentally investigates the dynamic process of water droplet impacting different wood surfaces and analyzes and discusses the impacting phenomena, phenomena distribution, droplet spreading dynamics, and maximum spread factor. The results show that the impacting process can be distinguished by Weber numbers and Reynolds numbers, and can be predicted by mathematical expressions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Aakhash Sundaresan, Atul Srivastava, Callum Atkinson
Summary: This study presents the first-ever application of an advanced methodology, combining two-color laser-induced phosphorescence and particle image velocimetry, to investigate the heat transfer mechanisms on the surface of a cylinder placed inside a confined square duct. The technique allows for simultaneous measurement of velocity and temperature fields, reducing the complexity and costs associated with separately measuring temperature distributions. Experimental observations show that increasing the mass flow rate enhances heat removal from the cylinder surface, and increasing the cylinder heat input enhances heat transfer in the rear portion of the cylinder.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Harish K. Patel, Sukhjeet Arora, Rutuja Chavan, Bimlesh Kumar
Summary: This study experimentally analyzed the multiscale statistical assessment of scour depth surrounding spur dikes with downward seepage. The research found that seepage affects the morphological behavior and hydrodynamic characteristics of the channel bed, leading to changes in scour formation. The rate of scour depth changes initially increases with higher seepage velocity but eventually becomes constant over time.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Justas Sereika, Paulius Vilkinis, Gediminas Skarbalius, Algis Dziugys, Nerijus Pedisius
Summary: This study experimentally investigated the pulsatile flow structure based on a transitional-type cavity. It was found that the pulsation amplitude has a more significant effect on the dynamics of recirculation zone than the pulsation frequency. Pulsatile flow can reduce the size of the recirculation zone.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Merav Arogeti, Eran Sher, Tali Bar-Kohany
Summary: This study provides a detailed exploration of the events that occur when a droplet hits a dry solid surface of various small sizes, with a focus on the deposition, receding breakup, and prompt splash phases. By utilizing non-dimensional analysis and graphical representation, the boundaries between different events are defined, and criteria for differentiation based on target-to-drop ratio, Reynolds, and Webber numbers are presented.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Tianxiong Li, Fei Wen, Yingchun Wu, Botong Wen, Lei Wang, Jinxin Guo, Xuecheng Wu
Summary: This study investigates the structure of the flow field induced by a strut in a scramjet and its influence on flame stabilization. Experimental and numerical analyses reveal that the flow field exhibits features beneficial for flame stabilization, but the asymmetry of the flow poses a challenge to flame establishment.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Syed Ehtisham Gillani, Yasir M. Al-Abdeli
Summary: This study investigates the asymmetry in bluff-body stabilised annular jets and finds that swirl can significantly mitigate the asymmetry and restore the symmetry of the jets. Moreover, increasing the Reynolds number and the swirl intensity can both decrease the asymmetry of the jets.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Utsav Bhardwaj, Rabindra Kumar, Shyama Prasad Das
Summary: This study presents an experimental investigation on flooding phenomenon in a pulsating heat pipe (PHP) unit cell, and analyzes the impact of flooding on the performance of PHP. The study recognizes three different flooding mechanisms and finds that currently accepted correlations for predicting flooding velocity are inaccurate. The study emphasizes the need for further research on flooding in PHPs.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)
Article
Thermodynamics
Yunpeng Xue, Yongling Zhao, Shuo-Jun Mei, Yuan Chao, Jan Carmeliet
Summary: This study investigates the impact of building morphology on local climate, air quality, and urban microclimate. The researchers conducted an experimental investigation in a large-scale water tunnel, analyzing heat and flow fields using Laser-induced Fluorescence (LIF) and Particle Image Velocimetry (PIV). The findings show that factors such as canyon configuration, buoyant force, and approaching flow magnitude significantly influence fluid flow in street canyons, and the morphology of the street canyon dominates ventilation rate and heat flux. For example, changing the aspect ratio of a street canyon can lead to a significant change in air ventilation rate, ranging from 0.02 to 1.5 under the same flow conditions.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2024)