Article
Chemistry, Physical
Khobaib Khobaib, Zbigniew Rozynek, Tomasz Hornowski
Summary: This study investigates the deformation and behavior of particle-covered droplets in nonuniform electric fields. It analyzes the effects of electrode geometry, electric potential, and droplet size on droplet deformation, and establishes a correlation between droplet deformation and the size of an opening in the particle shell. The study also explores the origins of liquid flows induced by the electric field in the sample cell.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Mechanics
Zhigang Huang, Luming Ge, Weixun Wei, Yu Deng, Junjun Lei
Summary: DEP-FFF is a promising method for fractionating particles with potential applications in biomedical, chemical, and environmental engineering. Particle deformation plays a critical role in the fractionation accuracy and viability of bioparticles.
Article
Physics, Fluids & Plasmas
Manash Pratim Borthakur, Binita Nath, Gautam Biswas
Summary: This study investigates the dynamics of compound droplets under the influence of an applied electric field and shear flow, considering both perfect dielectric and leaky dielectric fluids. The permittivity ratio between fluids and the ratio of electrical permittivity and conductivity play critical roles in modulating droplet deformation and orientation. Accumulated charge at interfaces modifies Coulombic forces, fundamentally altering droplet characteristics, and electric fields can induce droplet breakup.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Engineering, Chemical
Ning Li, Yunhui Pang, Zhiqian Sun, Yongxiang Sun, Zhuang Qi, Wangqing Li, Yue Liu, Bin Li, Zhenbo Wang, Hongbo Zeng
Summary: Polymers have a significant impact on the electrostatic demulsification efficiency of water-in-oil (W/O) emulsions by altering the motion characteristics of water droplets. The addition of polymers increases the polarity of the droplets, promoting their deformation and breakup under an electric field. The migration of polarized polymers and ions ultimately leads to droplet breakup.
SEPARATION AND PURIFICATION TECHNOLOGY
(2023)
Article
Engineering, Chemical
Ning Li, Zhiqian Sun, Yunhui Pang, Zhuang Qi, Wenchuan Liu, Wangqing Li, Mingze Sun, Bin Li, Zhenbo Wang
Summary: This study used molecular dynamics simulations to investigate the molecular mechanisms underlying the electrostatic coalescence of water droplets containing surfactants. Low concentrations of surfactants promote coalescence, while high concentrations have the opposite effect. The presence of surfactants reduces the oil-water interfacial tension and increases the critical electric field strength for droplet coalescence.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Engineering, Chemical
Jingchang Zhang, Shuli Shu, Xiaoping Guan, Ning Yang
Summary: This study investigates the effects of multiple breakup in shear flow using a phase-field lattice Boltzmann method, finding that the presence of surfactant alters the regime map of the system. The multiple-breakup regime widens and the coalescence regime narrows in the presence of surfactant, indicating a mesoscale behavior caused by the interaction between surfactant and shear flow.
CHEMICAL ENGINEERING SCIENCE
(2021)
Article
Engineering, Chemical
Sahil Kashyap, Zeyad Almutairi, Ning Qin, Pei Zhao, Sanjeev Bedi, David Johnson, Carolyn L. Ren
Summary: Understanding the effects of surfactant on the internal flow field of moving droplets is important for both fundamental research and practical applications. This study developed a laser-based phase-locking system coupled with a micro particle image velocimetry system to quantitatively measure the internal droplet flow field. By evaluating two surfactants at different concentrations, it was found that the shape and flow of the droplets were influenced. At low concentrations, flow retardation occurred due to the induced Marangoni flow opposing the internal flow. The achievement of complete remobilisation in the internal flow depended on the type, concentration, and operating regime of the surfactant.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Thermodynamics
Zhengwei Jiang, Yunhua Gan, Yanling Shi
Summary: Transient heat/mass transfer to a deformed droplet suspended in the ambient fluid in the presence of a steady electric field is investigated. A numerical model is established to simulate the flow field and heat transfer, and the results show that the transport mechanism is affected by the deformation rate. Conduction and convection play comparable roles, and deformation weakens both conduction and convection. The heat transfer rate of oblate droplets is less suppressed compared to prolate droplets.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Jiawen Zhang, Takaya Sato, Takeshi Ooyama, Keiji Koumura, Takahiro Ito, Yoshiyuki Tsuji
Summary: This paper presents experimental visualization results of sessile droplets in fully developed turbulent shear flows and their movement onset. The droplets are deformed and spread in a spanwise direction under the influence of turbulent velocity fluctuation. The contact angles of the droplets change symmetrically over time and are not clearly related to droplet oscillation. The droplet oscillation frequencies are well predicted by a model based on resonant vibrations, except for the lowest mode. The motion onset can be approximated by a simple empirical relation between the Weber and Reynolds numbers.
EXPERIMENTAL THERMAL AND FLUID SCIENCE
(2023)
Article
Chemistry, Physical
Ye Peng, Youyu Zhang, Zhixiang Liao, Yuan Fang, Bao Yu, Haifeng Gong
Summary: This study proposes a chaotic-pulse-width-modulation (CPWM) electric field for oil demulsification, in which the pulse width has a chaotic change while the duty cycle remains constant. A model of droplet deformation and vibration in oil is established, and the effects of duty cycle and electric field intensity on droplet vibration deformation are analyzed. The results show that the CPWM electric field has a wide frequency range and can induce chaotic characteristics in droplet deformation. The optimal duty cycle for CPWM electric field demulsification is 0.5, and the vibration amplitude of the droplet increases with increasing electric field intensity.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Engineering, Chemical
Haifeng Gong, Zhixiang Liao, Ye Peng, Zhi Qiu, Bao Yu, Youyu Zhang
Summary: The size of droplets in oil changes dynamically during demulsification, affecting the optimum demulsification electric field frequency. Constant pulsed electric field cannot meet the requirement of optimum frequency, while a variable frequency pulsed electric field can cater to the change in optimum frequency and has high demulsification ability. However, the dynamic characteristics of droplets in oil subjected to variable frequency pulsed electric field are not well understood. In this study, a chaotic pulse position modulation electric field is considered as a type of variable frequency pulsed electric field, and the dynamic and chaotic characteristics of droplet deformation in oil under this electric field are investigated.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Mathematics, Interdisciplinary Applications
Roozbeh Saghatchi, Murat Ozbulut, Mehmet Yildiz
Summary: The dynamics of a 2D double emulsion under the combined effects of the electric field and shear flow were studied using an incompressible smoothed particle hydrodynamics (ISPH) method. Six different systems with varying electrical properties were examined, showing that deformation is highly dependent on capillary and electrical capillary numbers as well as core to shell radius ratio. Electric force components and hydrodynamic stresses were calculated and discussed, leading to the realization that breakup can be avoided by adjusting these factors. Different breakup forms were comprehensively investigated.
COMPUTATIONAL MECHANICS
(2021)
Article
Engineering, Mechanical
Qinglei Zeng, Manxi Chen, Xiaoqi Yu, Wei Qi, Shengxin Zhu, Heng Yang, Hao-Sen Chen
Summary: Adiabatic shear band (ASB) is an important failure mechanism observed in metals and alloys under impact loading, with a two-dimensional propagating feature. However, in-situ characterization of temperature-deformation fields during ASB formation is challenging due to the small scales involved. In this study, a plane-array infrared imaging system and microspeckle-based digital image correlation technique were used to obtain the two-dimensional features of ASB evolution in titanium alloy specimens. Experimental characterization and simulation results were used to analyze the thermo-mechanical aspects of ASB formation.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Engineering, Chemical
Ye Peng, Zhixiang Liao, Youyu Zhang, Yuan Fang, Zhi Qiu, Bao Yu, Haifeng Gong
Summary: This article proposes a chaotic pulse group (CPG) electric field to improve the demulsification efficiency. By establishing a dynamic model of droplet deformation under CPG electric field, the influences of duty cycle and group pulse number on droplet deformation are analyzed, and the relaxation mechanism of droplet in CPG electric field is investigated.
CHEMICAL ENGINEERING RESEARCH & DESIGN
(2022)
Article
Mechanics
Sayan Das, Somnath Santra, Suman Chakraborty
Summary: Pattern formation and dynamics of interacting droplets in confined passages exhibit contrasting behavior compared to that of single droplets. By considering temperature-gradient-driven interfacial transport, we have identified four different modes of thermally activated migration of a droplet-pair in microchannels. We also propose the possibility of converting one pattern to another by modulating different tuning parameters. These findings have significant implications in various applications, such as materials processing and micro-reactor technology.
Article
Mechanics
Sheng Li, Haihu Liu, Jinggang Zhang, Fei Jiang, Guang Xi
Summary: The study proposes a color-gradient lattice Boltzmann model to simulate immiscible three-phase flows with contact-line dynamics. The model is validated against analytical solutions and used to study the displacement of residual oil during tertiary gas injection process. Results show that residual oil can be efficiently recovered through the formation of an oil spreading layer.
Article
Computer Science, Interdisciplinary Applications
Fei Jiang, Haihu Liu, Xian Chen, Takeshi Tsuji
Summary: In this paper, a numerical model for simulating the solid-liquid-gas three-phase flow in unconsolidated particle layers is developed. The model utilizes the discrete element method (DEM) and the lattice Boltzmann method (LBM) to propose a multiphase fluid-solid two-way coupling algorithm. The method is applied to simulate the upward migration of leaked gas bubbles through a brine-filled sediment column at the seafloor and investigate the influences of leak flow rate and interfacial tension on bubble rising behavior. The results indicate three different flow regimes, and the proposed numerical method accurately characterizes various multiphase interaction mechanisms.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Mechanics
Dong Wang, Ningning Wang, Haihu Liu
Summary: A three-dimensional lattice Boltzmann method is developed to investigate the deformation and breakup of a Newtonian droplet in the Giesekus fluid matrix under shear flow. The study explores the effects of Deborah number De, mobility parameter alpha, and solvent viscosity ratio beta on droplet deformation, and analyzes the modifications of normal viscous and elastic stresses on the droplet.
JOURNAL OF RHEOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Xitong Zhang, Jiangang Zhang, Haihu Liu, Pan Jia
Summary: In this study, the characteristics and influencing factors of a liquid column with evenly distributed particles on its surface were investigated using a three-dimensional lattice Boltzmann method. It was found that increasing particle concentration and slightly hydrophobic conditions can enhance the stability of the liquid column, and hydrophobic particles tend to assemble near the neck.
Editorial Material
Mechanics
Yan Wang, Haihu Liu, Haizhuan Yuan
Summary: Multiphase flows, which are widely present in various fields, present challenges for researchers due to complex interfaces and wide range of scales. However, recent advances in numerical methodologies, experimental techniques, and theoretical analysis tools have significantly contributed to the study of complex multiphase flow problems.
Article
Mechanics
Jinggang Zhang, Xitong Zhang, Wei Zhao, Haihu Liu, Youhua Jiang
Summary: In this study, the generation of surfactant-laden droplets in a T-junction was simulated using a lattice Boltzmann method. The concentration of surfactants was found to affect the droplet generation regime, shifting from squeezing to dripping and then to jetting as the surfactant concentration increases. The influence of surfactants on the upstream pressure and the role of surfactants under different capillary numbers were also investigated. Additionally, phase diagrams were established to describe the variation of the droplet generation regime with flow rate ratio and capillary number in both clean and surfactant-laden systems.
Article
Mechanics
Min Li, Haihu Liu, Yang Zhang, Pan Jia, Peihua Feng, Bin Yang
Summary: This study conducts a two-dimensional numerical investigation of particle entrainment in the presence of a large downstream circular obstacle. It aims to deepen the understanding of the entrainment mechanism and propose a dimensionless number to describe the entrainment threshold. The results show that the entrainment mechanism and threshold vary with different obstacle-to-particle radius ratios and Reynolds numbers.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Engineering, Mechanical
Jiankun Zhang, Haihu Liu
Summary: This study investigates the effect of blade tip pattern on blade load and vibration characteristics in a twin-stage axial fan. The results show that the proposed blade tip patterns not only increase stress and deformation, but also significantly increase resonance margin near the rated speed.
JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY
(2022)
Article
Thermodynamics
Jinggang Zhang, Wei Zhao, Haihu Liu, Guang Xi
Summary: A hybrid lattice Boltzmann and finite difference method is presented to simulate two-phase flows with unequal densities and insoluble surfactants. The study investigates the effects of surfactants on bubble motion, deformation, and coalescence. The results show that surfactants retard bubble motion and deformation, but the effect decreases with increasing density ratio (Bond number). Furthermore, the presence of surfactants delays or promotes bubble coalescence depending on the Galilei number and radius ratios of the bubbles.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Chemical
Xitong Zhang, Jinggang Zhang, Haihu Liu
Summary: In this study, a lattice Boltzmann method is employed to simulate a particle-laden droplet under a simple shear flow. The effects of particle concentration, viscosity ratio of droplet to ambient fluid, and particle inertia on droplet deformation and particle movement are investigated. It is found that the addition of particles reduces the interfacial free energy and leads to increased droplet deformation. Additionally, the viscosity ratio and particle inertia both influence the droplet deformation, with the former showing a monotonic decrease and the latter having a significant effect only at high Reynolds numbers.
Article
Mechanics
Sheng Li, Haihu Liu, Rui Wu, Jianchao Cai, Guang Xi, Fei Jiang
Summary: In this work, theoretical modelling, quasi-3D simulations, and micromodel experiments are used to study spontaneous imbibition with gravity in porous media micromodels. A theoretical model for predicting the imbibition length and compact displacement process is developed. The study shows the significant influence of gravity, equivalent width, and interface curvature on the imbibition process.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Jiankun Zhang, Haihu Liu
Summary: The erosion caused by solid particles poses a significant threat to the safety and reliability of turbines. This study numerically investigates the impact of particle size, blade tip clearance, rotation speed, and off-design condition on erosion and performance using the Oka erosion model. The results show that particle injection leads to decreased efficiency, with high erosion occurring near the trailing edge at the pressure side and the leading edge at the suction side. The erosion can be alleviated by larger tip clearances and lower rotation speeds, while the off-design condition significantly reduces efficiency and increases erosion.
Article
Mechanics
Ronghong Zhou, Sheng Li, Liang Shi, Ningning Wang, Yong Liu, Haihu Liu
Summary: In this study, a theoretical and numerical investigation is carried out on the flow of a compound droplet through a single pore-throat structure. A theoretical model is developed to predict whether the compound droplet can penetrate the throat by quantifying the capillary pressures in the pore and throat under different geometrical conditions. Lattice Boltzmann simulations are also conducted to validate the theoretical model and explore the influence of various factors on the invasion behavior of the compound droplet.
Article
Engineering, Multidisciplinary
Muhammad Sami Rashad, Haihu Liu, Shan Ali Khan
Summary: In this study, a mathematical modeling approach was used to investigate the unsteady stagnation point flow of Oldroyd-B nanofluid, taking into account the thermal conductivity and solutal diffusivity with bioconvection mechanism. The effects of Joule heating, Arrhenius activation energy, and convective boundary conditions were considered. The results showed that increasing the buoyancy ratio parameter reduces fluid velocity, while increasing the mixed convective parameter enhances fluid flow. The temperature profile is influenced by nonlinear thermal radiation and temperature dependent thermal conductivity. The concentration profiles of nanoparticles exhibit opposite behaviors for the Brownian motion coefficient and thermophoresis diffusion parameter. By varying the Peclet number, the microorganisms profile is observed to decrease. The findings of this study are significant for controlling and optimizing heat transfer in industrial applications.
CMES-COMPUTER MODELING IN ENGINEERING & SCIENCES
(2022)
