Article
Chemistry, Physical
Ziming Lin, Kun Zhao, Situo Li, Jianan Qian, Hua Wang, Zhenhua Tang, Tong Cui, Zhirong Wang
Summary: The pulsation frequency of inclined jet fire was studied systematically in this research. Experiments were conducted on syngas jet fire with a 15 mm nozzle diameter at different fuel flow rates (2.5 L/min-20 L/min) and inclination angles (0 degrees-90 degrees). The pulsation frequency of the inclined jet flame was quantified by applying FFT to the time variations of image correlation coefficient, flame height, and flame width, corresponding to the global, vertical, and spatial pulsation frequencies, respectively. The results showed that the vertical pulsation frequency could only be derived for jet flames with significant clip-off. The effect of inclination angle on the pulsation frequency depended on the fuel flow rate.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Mathematics, Applied
Ye Zhou, Robin J. R. Williams, Praveen Ramaprabhu, Michael Groom, Ben Thornber, Andrew Hillier, Wouter Mostert, Bertrand Rollin, S. Balachandar, Phillip D. Powell, Alex Mahalov, N. Attal
Summary: Hydrodynamic instabilities such as Rayleigh-Taylor and Richtmyer-Meshkov instabilities are often found in conjunction with Kelvin-Helmholtz instability in natural phenomena and engineering applications, resulting in turbulent mixing and significant impact on flow development and material properties. These instabilities pose challenges to numerical modeling due to the sharp interface separating fluids, with recent progress made in addressing these challenges. Applications of these instabilities include solar prominences, supernovae, inertial fusion experiments, and scramjets.
PHYSICA D-NONLINEAR PHENOMENA
(2021)
Article
Physics, Multidisciplinary
Sun Wei, Lu Chong, Lei Zhu, Zhong Jia-Yong
Summary: Rayleigh-Taylor instability is a fundamental physical phenomenon in fluids and plasmas, playing a significant role in various fields including astrophysics, space physics, and engineering. A new experimental scheme is proposed to study the influence of magnetic fields on magnetized RTI, showing that a magnetic field perpendicular to flow direction can stabilize the instability and Kelvin-Helmholtz vortex.
ACTA PHYSICA SINICA
(2022)
Article
Mechanics
Jianming Li, Juchun Ding, Xisheng Luo, Liyong Zou
Summary: The instability of a heavy gas layer induced by a cylindrical convergent shock is studied experimentally and numerically. The development of the outer interface is affected by the outgoing rarefaction wave generated at the inner interface, while the development of the inner interface is insensitive to the layer thickness. A theoretical model is constructed considering all the significant effects and reasonably predicts the experimental and numerical results.
Article
Mechanics
Xiang-dong Deng, Huan-ran Wang, Xiao Cui, Bao-lu Shi, Yong Tang, Ning-fei Wang
Summary: This work examines the linear instability of a viscoelastic confined liquid jet, considering the acoustic oscillations and using the Floquet theory. The unstable regions are dominated by capillary instability, Kelvin-Helmholtz instability (KHI), and parametric instability. The impact of heat and mass transfer in different unstable regions is discussed, as well as the different instability mechanisms for different azimuthal wavenumbers.
Article
Environmental Sciences
Alexander Osadchiev, Alexandra Gordey, Alexandra Barymova, Roman Sedakov, Vladimir Rogozhin, Roman Zhiba, Roman Dbar
Summary: This study focuses on the instabilities at the interfaces between small river plumes and ambient seawater. High-resolution aerial remote sensing and in situ measurements are used to examine these instabilities. Both Rayleigh-Taylor and Kelvin-Helmholtz instabilities are observed, inducing mass transport and modifying the salinity structure and mixing at the plume-sea interfaces. Additionally, wind-driven Stokes transport affects the spread of river-borne floating particles.
Article
Physics, Multidisciplinary
Wei Sun, Chong Lv, Li Feng, Jianzhao Wang, Zhao Wang, Chuangye He
Summary: In this work, two-dimensional numerical simulations of laser-driven Rayleigh-Taylor instability (RTI) with different density perturbations are performed using a radiation magnetohydrodynamic simulation program (FLASH). The effect of the applied magnetic field on the evolution of RTI at different Atwood numbers is systematically discussed. The results show that reducing the Atwood number weakens the mixing of fluids and has a strong stabilizing effect on the RTI, and introducing an external magnetic field parallel to the perturbation wave vector further inhibits the development of RTI and Kelvin-Helmholtz instability, with magnetic pressure playing a dominant role. The study results are important to gaining an in-depth understanding of the mixing of magnetic fluids and the magnetic field evolution at the instability interface and provide a reference for subsequent experimental studies on the related magnetization RTI.
FRONTIERS IN PHYSICS
(2023)
Article
Mechanics
M. Vadivukkarasan
Summary: This study analyzes the instability mechanism responsible for forming droplets and aerosols during respiratory events, proposing a mathematical framework and suggesting the Rayleigh-Taylor-Kelvin-Helmholtz model as a powerful tool. It highlights the possibility of respiratory droplet formation over multiple instabilities and provides a fundamental understanding.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2021)
Article
Multidisciplinary Sciences
Galal M. Moatimid, D. M. Mostafa
Summary: This study investigates a nonlinear axisymmetric streaming flow obeying the Rivlin-Ericksen viscoelastic model and overloaded by suspended dust particles. The theoretical nonlinear stability standards are determined by analyzing the appropriate nonlinear applicable boundary conditions. The findings of this research have important implications for wastewater treatment, petroleum transport and various practical engineering applications.
SCIENTIFIC REPORTS
(2023)
Article
Engineering, Multidisciplinary
Yerbol Palzhanov, Alexander Zhiliakov, Annalisa Quaini, Maxim Olshanskii
Summary: This paper presents a thermodynamically consistent phase-field model of two-phase flow of incompressible viscous fluids which allows for a non-linear dependence of the fluid density on the phase-field order parameter. An unfitted finite element method is applied to discretize the system, and a fully discrete time-stepping scheme is introduced to ensure the stability of the numerical solution. Numerical examples demonstrate the stability, accuracy, and overall efficiency of the approach, revealing interesting dependencies of flow statistics on geometry in two-phase surface flows.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Thermodynamics
Xiaochun Xue, Yonggang Yu
Summary: This study focuses on the energy release and flow behavior of liquid propellant in the internal ballistics cycle of a liquid launching system. A new type of stepped-wall chamber structure is proposed to improve the thermal jet and enhance the energy release efficiency. The combustion of the liquid propellant strongly depends on the hydrodynamic instability of the gas-liquid mixing process. The chamber structure is verified to control this instability problem and different stepped-wall chambers are investigated to understand their effects on the flow and energy release behavior of the liquid propellant.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Jianlong Chang, Liujing He, Lianhua Chen, Zhangfeng Shen, Lai Fatt Chuah, Awais Bokhari, Jiri Jaromir Klemes, Ning Han
Summary: This paper investigates the influence of Weber number, Oh, and momentum flux ratio q on the atomization in subsonic crossflow, and compares the jet fragmentation morphology and atomization characteristics under different operating conditions. The results show that Weber number has a pronounced effect on the fragmentation pattern and atomization characteristics, while momentum flux ratio q plays a key role in the penetration depth.
Article
Mechanics
Hui Zhao, Dung Nguyen, Daniel Edgington-Mitchell, Julio Soria, Hai-Feng Liu, Damon Honnery
Summary: This study aims to investigate the largest diameter of falling drop in the up-gas flow. The phenomenon of drop breakup in the airflow, known as secondary atomization, is commonly observed in nature and industry. The critical Weber number is used to determine the beginning of drop breakup. This study explains the different critical Weber numbers for free-fall raindrops breakup and secondary atomization based on the Rayleigh-Taylor instability. The study proposes a theoretical criterion for the largest raindrop size and suggests a map of falling drop size regions to explain the occurrence of super-large raindrops. Additionally, the findings of this study have practical implications for reducing drop entrainment in washing towers.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2023)
Article
Mechanics
Si Kasmaiee, M. Tadjfar
Summary: The influence of changing the injection angle of a liquid jet injected into airstream in crossflow was investigated. Different breakup regimes occur based on the relative importance of the aerodynamic forces of the crossflow to the liquid momentum and surface tension forces. The behavior of the liquid jet penetration into the airstream varies with the injection angle and gas Weber number.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Mechanics
Thi Thai Le, Thorsten Koch
Summary: This research aims to analyze the interface stability of the tangential-velocity discontinuity between two compressible gases using Darcy's model and including the porosity effect, providing a basis for considering underground gas storage, particularly for storing hydrogen. The relation between Mach number M, viscosity mu, and porosity epsilon on the stability of the interface is shown to affect gases' withdrawal and injection processes, helping determine the velocity at which gas can be extracted and injected effectively for storage. Solid walls along the flow direction significantly impact the critical values of these parameters regarding the stability of the interface, with bounded flows providing a more realistic approach to the problem, especially in two-dimensional gas flows in storages and pipes.
Article
Mechanics
Nicolas Bouvet, Savannah S. Wessies, Eric D. Link, Stephen A. Fink
Summary: This study presents a framework to characterize firebrand flows and compare exposure through the use of a measurement device and data processing methods. The ability to perform exposure comparisons and recognize combustion states is demonstrated.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
P. Botticini, G. Lavalle, D. Picchi, P. Poesio
Summary: This study investigates the gravity-driven liquid layer problem on an inclined plate, taking into account the variable density of the fluid. The study examines the influence of density variation on the formulation of a depth-averaged model and the role of compressibility in long-wave interfacial instability.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Jean-Paul Caltagirone
Summary: This article introduces a method for modeling capillary flows on a surface or at the interface of two fluids. The method involves handling the two components of capillary acceleration using the divergence and curl of surface normal. The proposed formulation is characterized by directional curvature based on dihedral angle, intrinsic anisotropic surface tension per unit mass, and introduction of capillary potential.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Qi-Teng Zheng, Chun-Bai-Xue Yang, Shi-Jin Feng, Yu-Chen Song, Yong Zhao, Yu-Lin Wu
Summary: This paper proposes a new two-phase partitioning boundary model to accurately predict the drying process of a porous medium from saturated to unsaturated conditions. The model is validated through laboratory soil drying tests and the study also investigates the effects of air-water interfacial area and water retention parameters on the drying process.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Alexandra Metallinou Log, Morten Hammer, Svend Tollak Munkejord
Summary: Flashing flow is commonly found in industrial systems and accurate flashing models are essential for the design of safe and efficient CO2 transportation systems. We propose a homogeneous flashing model that takes into account the physical phenomena of phase change. The model is fitted using CO2 pipe depressurization data and we find that the same model parameters can be applied for different cases.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Q. Tan, S. A. Hosseini, A. Seidel-Morgenstern, D. Thevenin, H. Lorenz
Summary: The possible impact of temperature differences during crystal growth is investigated in this study. A numerical model is developed to simulate the crystallization dynamics of (S)-mandelic acid, taking into account temperature effects. The study shows that the heat generation at the crystal interface has only a small effect on the surrounding temperature field.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Hideki Murakawa, Sana Maeda, Sven Eckert
Summary: This study investigates the behavior of bubbles in a liquid metal under the influence of a magnetic field, particularly bubble chains. The results show that increasing the magnetic field strength suppresses the oscillations of the bubbles and concentrates their crossing positions in a specific area. Applying these findings to numerical models can further optimize continuous casting processes.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Johanna Potyka, Kathrin Schulte
Summary: This paper presents an advanced Volume of Fluid (VOF) method for performing three-dimensional Direct Numerical Simulations (DNS) of the interaction of two immiscible fluids in a gaseous environment with large topology changes. The method includes efficient reconstruction of phase boundaries near the triple line using a Piecewise Linear Interface Calculation (PLIC) method and enhanced surface force modeling with the Continuous Surface Stress (CSS) model. Implementation of these methods in the multi-phase flow solver Free Surface 3D (FS3D) yielded successful validation. The simulations provide valuable insights into the collision process and can support future modeling of immiscible liquid interaction.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Martin Rohde, Sebastian Burgmann, Uwe Janoske
Summary: This study investigates the effect of superimposing an incident flow and two-dimensional vibration on the critical air flow velocity required for the detachment of a droplet. The results show that oscillatory excitation at specific frequencies can significantly reduce the critical velocity for droplet detachment.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Tea-Woo Kim, Baehyun Min
Summary: Liquid-gas two-phase slug flow is a complex flow pattern in energy systems, and accurately predicting slug liquid holdup is crucial for system design and operation. Existing HLLS models have limited applicability due to a lack of physical basis. This study proposes a new dimensionless number SP and correlates it with HLLS data, resulting in a unified HLLS correlation that agrees closely with experimental data.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Christian Lieber, Stephan Autenrieth, Kai-Yannic Schoenewolf, Amy Lebanoff, Rainer Koch, Sterling Smith, Paul Schlinger, Hans-Joerg Bauer
Summary: The observation of acoustically levitated droplets offers great potential for studying their evaporation characteristics. The main objective of this study is to present an experimental setup that minimizes the disturbing effects of the levitation technique in order to investigate convective heat and mass transfer during droplet evaporation.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Facundo Cabrera-Booman, Nicolas Plihon, Mickael Bourgoin
Summary: The settling behavior of individual spheres in a quiescent fluid was experimentally studied. The mean trajectory angle with the vertical showed complex behavior as the parameters Gamma and Ga varied. The transition from planar to non-planar trajectories and the emergence of semi-helical trajectories were observed, especially for denser spheres.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Hongbin Wang, Hanwen Luo, Jinbiao Xiong
Summary: This article introduces an iterative screening method for closure models in nucleate boiling flow simulation, and demonstrates its accuracy through experiments.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Alexandra Metallinou Log, Morten Hammer, Han Deng, Anders Austegard, Armin Hafner, Svend Tollak Munkejord
Summary: This study investigates the rapid depressurization of liquid CO2 and compares the predictions of different models. It is found that higher temperatures result in shorter relaxation times.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)
Article
Mechanics
Rizwan Zahoor, Sasa Bajt, Bozidar Sarler
Summary: This numerical study evaluates the jet characteristics of non-Newtonian power-law fluids in a gas dynamic virtual nozzle. The results show that shear-thinning fluids result in thicker, longer, and slower jets compared to shear-thickening fluids. Additionally, a dripping-jetting phase diagram of the nozzle is obtained by varying the power law index, gas, and liquid flow rates.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2024)