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Applied Sciences
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Multiphase Flows in Microfluidics: Fundamentals and Applications
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Multiphase Flows in Microfluidics: Fundamentals and Applications

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Fluid Science and Technology".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 27945

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Prof. Dr. Jianzhong Lin

E-Mail Website
Guest Editor
School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, China
Interests: multiphase flow; microfluids and nanofluids; turbulence and coherent structure; fluid machinery
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Microfluidics, a cutting-edge field used for a variety of applications in advanced materials, biochemistry, new energy, single-cell/single-molecule studies, human health, and so forth, has developed rapidly in the last two decades. Among the different applications, multiphase flow is the fundamental and vital element in various microfluidic subjects, such as emulsion, droplet, bubble, micromixer/reactor, and microswimmer/robot. Therefore, this Special Issue aims to host original research or review articles addressing the fundamentals and applications of any functional multiphase flow in microfluidics. The potential topics include (but are not limited to) multiphase flow, emulsion, droplet, bubble, micromixer, microswimmer, and particle manipulation. Experimental and numerical studies are welcome.

Prof. Dr. Jianzhong Lin
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • multiphase flow
  • microfluidics
  • nanofluidics
  • emulsions
  • droplets
  • bubbles
  • micromixing
  • microswimmer
  • particle manipulation

Published Papers (16 papers)

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Editorial

Jump to: Research, Review

4 pages, 177 KiB  
Editorial
Special Issue on Multiphase Flows in Microfluidics: Fundamentals and Applications
by Jianzhong Lin
Appl. Sci. 2023, 13(10), 5907; https://0-doi-org.brum.beds.ac.uk/10.3390/app13105907 - 11 May 2023
Viewed by 1050
Abstract
Microfluidics, a cutting-edge field involving various applications in advanced materials, new energy, single-cell/single-molecule studies, human health, biomedicine, and so forth, has advanced rapidly in the last two decades [...] Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)

Research

Jump to: Editorial, Review

15 pages, 3480 KiB  
Article
Research on the Influence of Inlet Velocity on Micron Particles Aggregation during Membrane Filtration
by Peifeng Lin, Qing Wang, Xiaojie Xu, Zuchao Zhu, Qiangmin Ding and Biaohua Cai
Appl. Sci. 2022, 12(15), 7869; https://0-doi-org.brum.beds.ac.uk/10.3390/app12157869 - 05 Aug 2022
Cited by 1 | Viewed by 1033
Abstract
Membrane filtration is an efficient wastewater treatment technology. However, sludge particles will easily aggregate and deposit upon the membrane surface, which will decrease the water productivity of membrane filaments. Focusing on the influence of velocity on particle behavior, experimental and numerical research was [...] Read more.
Membrane filtration is an efficient wastewater treatment technology. However, sludge particles will easily aggregate and deposit upon the membrane surface, which will decrease the water productivity of membrane filaments. Focusing on the influence of velocity on particle behavior, experimental and numerical research was carried out. The k−ε turbulent model, porous media model and DPM model were adopted in the simulation. The flow characteristics including pressure, velocity and particle concentration contour are discussed using different inlet velocities of 0.6, 0.8, 1 m/s. The effects of gravity were also investigated. The final evaluation suggests the best working conditions in three scenarios, which could help to suppress membrane pollution. The results indicate that when the inlet velocity is about 1 m/s, particle deposition is weakest, resulting in better water productivity. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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14 pages, 755 KiB  
Article
Pressure Drop and Particle Settlement of Gas–Solid Two-Phase Flow in a Pipe
by Wenqian Lin, Liang Li and Yelong Wang
Appl. Sci. 2022, 12(3), 1623; https://0-doi-org.brum.beds.ac.uk/10.3390/app12031623 - 03 Feb 2022
Cited by 2 | Viewed by 2190
Abstract
Particle settlement and pressure drop in a gas–solid two-phase flow in a pipe with a circular cross-section are studied at mixture inlet velocities (V) ranging from 1 m/s to 30 m/s, particle volume concentrations (αs) ranging from 1% [...] Read more.
Particle settlement and pressure drop in a gas–solid two-phase flow in a pipe with a circular cross-section are studied at mixture inlet velocities (V) ranging from 1 m/s to 30 m/s, particle volume concentrations (αs) ranging from 1% to 20%, particle mass flows (ms) ranging from 5 t/h to 25 t/h, and particle diameters (dp) ranging from 50 μm to 1000 μm. The momentum equations are based on a two-fluid model and are solved numerically. Some results are validated through comparison with the experimental results. The results showed that the gas and particle velocity distributions are asymmetrical around the center of the pipe and that the maximum velocity point moves up. The distance between the radial position of the maximum velocity and the center line for the gas is larger than that for the particles. The particle motion lags behind that of the gas flow. The particle settlement phenomenon is more serious, and the particle distribution on the cross-section is more inhomogeneous as the V, αs, and ms decrease and as dp increases. It can be divided into three areas according to the pressure changes along the flow direction, and the distinction between the three areas is more obvious as the αs increases. The pressure drop per unit length increases as the V, αs and ms increases and as dp decreases, Finally, the expressions of the settlement index and pressure drop per unit length as functions of V, αs, ms, and dp are derived based on the numerical data. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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15 pages, 6970 KiB  
Article
Numerical Simulation of Non-Spherical Submicron Particle Acceleration and Focusing in a Converging–Diverging Micronozzle
by Yanru Wang, Jiaxin Shen, Zhaoqin Yin and Fubing Bao
Appl. Sci. 2022, 12(1), 343; https://0-doi-org.brum.beds.ac.uk/10.3390/app12010343 - 30 Dec 2021
Cited by 4 | Viewed by 1574
Abstract
Submicron particles transported by a Laval-type micronozzle are widely used in micro- and nano-electromechanical systems for the aerodynamic scheme of particle acceleration and focusing. In this paper, the Euler–Lagrangian method is utilized to numerically study non-spherical submicron particle diffusion in a converging–diverging micronozzle [...] Read more.
Submicron particles transported by a Laval-type micronozzle are widely used in micro- and nano-electromechanical systems for the aerodynamic scheme of particle acceleration and focusing. In this paper, the Euler–Lagrangian method is utilized to numerically study non-spherical submicron particle diffusion in a converging–diverging micronozzle flow field. The influence of particle density and shape factor on the focusing process is discussed. The numerical simulation shows how submicron particle transporting with varying shape factors and particle density results in different particle velocities, trajectories and focusing in a micronozzle flow field. The particle with a larger shape factor or larger density exhibits a stronger aerodynamic focusing effect in a supersonic flow field through the nozzle. In the intersection process, as the particle size increases, the position of the particle trajectory intersection moves towards the throat at first and then it moves towards the nozzle outlet. Moreover, the influence of the thermophoretic force of the submicron particle on the aerodynamic focusing can be ignored. The results will be beneficial in technological applications, such as micro-thrusters, microfabrication and micro cold spray. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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15 pages, 6222 KiB  
Article
Numerical Study on the Rising Motion of Bubbles near the Wall
by Kaixin Zhang, Yongzheng Li, Qi Chen and Peifeng Lin
Appl. Sci. 2021, 11(22), 10918; https://0-doi-org.brum.beds.ac.uk/10.3390/app112210918 - 18 Nov 2021
Cited by 9 | Viewed by 1648
Abstract
Based on the volume of fluid method (VOF), the rising characteristics of bubbles in near-wall static water are studied. In this study, the influence of the wall on the rising motion of the bubble was studied by changing the distance of the bubble [...] Read more.
Based on the volume of fluid method (VOF), the rising characteristics of bubbles in near-wall static water are studied. In this study, the influence of the wall on the rising motion of the bubble was studied by changing the distance of the bubble wall, the diameter of the bubble, the arrangement of the bubble and the size ratio, etc. The influence is expressed as the average swing amplitude of the “Z”-shaped motion when the bubble rises. The study found that in the case of a single bubble, the wall surface has a certain influence on the rise of the bubble, and its degree is affected by the bubble wall distance and the bubble diameter. The influence of bubble wall distance is more obvious. The greater the bubble wall distance, the less the bubble is affected by the wall; in the case of double bubbles, the influence of the interaction force between the bubbles is significantly greater than the wall surface. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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10 pages, 24772 KiB  
Article
Research on the Inertial Migration Characteristics of Bi-Disperse Particles in Channel Flow
by Dongmei Chen, Jianzhong Lin and Xiao Hu
Appl. Sci. 2021, 11(19), 8800; https://0-doi-org.brum.beds.ac.uk/10.3390/app11198800 - 22 Sep 2021
Cited by 5 | Viewed by 1419
Abstract
The inertial focusing effect of particles in microchannels shows application potential in engineering practice. In order to study the mechanism of inertial migration of particles with different scales, the motion and distribution of two particles in Poiseuille flow are studied by the lattice [...] Read more.
The inertial focusing effect of particles in microchannels shows application potential in engineering practice. In order to study the mechanism of inertial migration of particles with different scales, the motion and distribution of two particles in Poiseuille flow are studied by the lattice Boltzmann method. The effects of particle size ratio, Reynolds number, and blocking rate on particle inertial migration are analyzed. The results show that, at a high blocking rate, after the same scale particles are released at the same height of the channel, the spacing between the two particles increases monotonically, and the change in the initial spacing has little effect on the final spacing of inertial migration. For two different size particles, when the smaller particle is downstream, the particle spacing will always increase and cannot remain stable. When the larger particle is downstream, the particle spacing increases firstly and then decreases, and finally tends to be stable. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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13 pages, 4951 KiB  
Article
Fibers Effects on Contract Turbulence Using a Coupling Euler Model
by Wei Yang and Pei Hu
Appl. Sci. 2021, 11(15), 7126; https://0-doi-org.brum.beds.ac.uk/10.3390/app11157126 - 02 Aug 2021
Cited by 1 | Viewed by 1313
Abstract
Fiber additive will induce the rheological behavior of suspension, resulting in variation in velocity profile and fiber orientation especially for the non-dilute case. Based on the fluid-solid coupling dynamics simulation, it shows that the fiber orientation aligns along the streamline more and more [...] Read more.
Fiber additive will induce the rheological behavior of suspension, resulting in variation in velocity profile and fiber orientation especially for the non-dilute case. Based on the fluid-solid coupling dynamics simulation, it shows that the fiber orientation aligns along the streamline more and more quickly in the central turbulent region as the fiber concentration increases, especially contract ratio Cx > 4. However, fibers tend to maintain the original uniform orientation and are rarely affected by the contract ratio in the boundary layer. The fibers orientation in the near semi-dilute phase is lower than that in the dilute phase near the outlet, which may be the result of the hydrodynamic contact lubrication between fibers. The orientation distribution and concentration of the fibers change the viscous flow mechanism of the suspension microscopically, which makes a velocity profile vary with the phase concentration. The velocity profile of the approaching semi-dilute phase sublayer is higher than that of the dilute and semi-dilute phases on the central streamline and in the viscous bottom layer, showing weak drag reduction while the situation is opposite on the logarithmic layer of the boundary layer. The relevant research can provide a process strategy for fiber orientation optimization and rheological control in the industrial applications of suspension. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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17 pages, 6044 KiB  
Article
Sedimentation of Two Side-by-Side Heavy Particles of Different Density in a Shear-Thinning Fluid with Viscoelastic Properties
by Sensen Yang, Chengxu Tu, Minglu Dai, Xianfu Ge, Rongjun Xu, Xiaoyan Gao and Fubing Bao
Appl. Sci. 2021, 11(15), 7113; https://0-doi-org.brum.beds.ac.uk/10.3390/app11157113 - 31 Jul 2021
Cited by 5 | Viewed by 1945
Abstract
Particle sedimentation has widely existed in nature and engineering fields, and most carrier fluids are non-Newtonian. Recently, the manipulation of a settling particle in liquid has been a topic of high interest to those involved in engineered processes such as composite materials, pharmaceutical [...] Read more.
Particle sedimentation has widely existed in nature and engineering fields, and most carrier fluids are non-Newtonian. Recently, the manipulation of a settling particle in liquid has been a topic of high interest to those involved in engineered processes such as composite materials, pharmaceutical manufacture, chemistry and the petroleum industry. Compared with Newtonian fluid, the viscosity of non-Newtonian fluid is closely related to the shear rate, leading to a single settling particle having different dynamic behaviors. In this article, the trajectories and velocities of two side-by-side particles of different densities (heavy and light) settling in a shear-thinning fluid with viscoelastic property were studied, as well as that for the corresponding single settling particle. Regardless of the difference in the particle density, the results show the two-way coupling interaction between the two side-by-side settling particles. As opposed to a single settling particle, the wake of the heavier particle can clearly attract or rebound the light particle due to the shear-thinning or viscoelastic property of the fluid. Regarding the trajectories of the light particle, three basic path types were found: (i) the light particle is first attracted and then repelled by the wake of the heavy one; (ii) the light particle approaches and then largely traces within the path of the heavy one in the limited field of view; (iii) the light particle is first slightly shifted away from its original position and then returns to this initial position. In addition to this, due to the existence of a corridor of reduced viscosity and negative wake generated by the viscoelastic property, the settling velocity of a light particle can exceed the terminal velocity of a single particle of the same density. On the other hand, the sedimentation of the light particle can induce the distinguishable transverse migration of the heavy one. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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13 pages, 5150 KiB  
Article
Polymerization and Collision in High Concentrations for Brownian Coagulation
by Xiaoyue Wang, Yueyan Liu, Taiquan Wu and Mingzhou Yu
Appl. Sci. 2021, 11(15), 6815; https://0-doi-org.brum.beds.ac.uk/10.3390/app11156815 - 24 Jul 2021
Cited by 1 | Viewed by 1631
Abstract
Aggregation always occurs in industrial processes with fractal-like particles, especially in dense systems (the volume fraction, ϕ>1%). However, the classic aggregation theory, established by Smoluchowski in 1917, cannot sufficiently simulate the particle dynamics in dense systems, particularly those [...] Read more.
Aggregation always occurs in industrial processes with fractal-like particles, especially in dense systems (the volume fraction, ϕ>1%). However, the classic aggregation theory, established by Smoluchowski in 1917, cannot sufficiently simulate the particle dynamics in dense systems, particularly those of generat ed fractal-like particles. In this article, the Langevin dynamic was applied to study the collision rate of aggregations as well as the structure of aggregates affected by different volume fractions. It is shown that the collision rate of highly concentrated particles is progressively higher than that of a dilute concentration, and the SPSD (self-preserving size distribution) is approached (σg,n≥1.5). With the increase in volume fraction, ϕ, the SPSD broadens, and the geometric standard is 1.54, 1.98, and 2.73 at ϕ=0.1, 0.2, and 0.3. When the volume fraction, ϕ, is higher, the radius of gyration is smaller with the same cluster size (number-based), which means the particle agglomerations are in a tighter coagulation. The fractal-like property Df is in the range of 1.60–2.0 in a high-concentration system. Knowing the details of the collision progress in a high-concentration system can be useful for calculating the dynamics of coagulating fractal-like particles in the industrial process. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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18 pages, 5245 KiB  
Article
Contribution of Particle–Wall Distance and Rotational Motion of a Single Confined Elliptical Particle to the Effective Viscosity in Pressure-Driven Plane Poiseuille Flows
by Misa Kawaguchi, Tomohiro Fukui and Koji Morinishi
Appl. Sci. 2021, 11(15), 6727; https://0-doi-org.brum.beds.ac.uk/10.3390/app11156727 - 22 Jul 2021
Cited by 5 | Viewed by 1464
Abstract
Rheological properties of the suspension flow, especially effective viscosity, partly depend on spatial arrangement and motion of suspended particles. It is important to consider effective viscosity from the microscopic point of view. For elliptical particles, the equilibrium position of inertial migration in confined [...] Read more.
Rheological properties of the suspension flow, especially effective viscosity, partly depend on spatial arrangement and motion of suspended particles. It is important to consider effective viscosity from the microscopic point of view. For elliptical particles, the equilibrium position of inertial migration in confined state is unclear, and there are few studies on the relationship between dynamics of suspended particles and induced local effective viscosity distribution. Contribution of a single circular or elliptical particle flowing between parallel plates to the effective viscosity was studied, focusing on the particle–wall distance and particle rotational motion using the two-dimensional regularized lattice Boltzmann method and virtual flux method. As a result, confinement effects of the elliptical particle on the equilibrium position of inertial migration were summarized using three definitions of confinement. In addition, the effects of particle shape (aspect ratio and confinement) on the effective viscosity were assessed focusing on the particle–wall distance. The contribution of particle shape to the effective viscosity was found to be enhanced when the particle flowed near the wall. Focusing on the spatial and temporal variation of relative viscosity evaluated from wall shear stress, it was found that the spatial variation of the local relative viscosity was larger than temporal variation regardless of the aspect ratio and particle–wall distance. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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18 pages, 944 KiB  
Article
Simulation of Aerosol Evolution within Background Pollution for Nucleated Vehicle Exhaust via TEMOM
by Can Tu, Yueyan Liu, Taiquan Wu and Mingzhou Yu
Appl. Sci. 2021, 11(10), 4552; https://0-doi-org.brum.beds.ac.uk/10.3390/app11104552 - 17 May 2021
Cited by 1 | Viewed by 1318
Abstract
This work is intended to study the effect of background particles on vehicle emissions in representative realistic atmospheric environments. The coupling of Reynolds-Averaged Navier–Stokes equation (RANS) and Taylor-series Expansion Method Of Moments (TEMOM) is performed to track the emissions of the vehicle and [...] Read more.
This work is intended to study the effect of background particles on vehicle emissions in representative realistic atmospheric environments. The coupling of Reynolds-Averaged Navier–Stokes equation (RANS) and Taylor-series Expansion Method Of Moments (TEMOM) is performed to track the emissions of the vehicle and simulating the evolution of the matters. The transport equation of mass, momentum, heat, and the first three orders of moments are taken into account with the effect of binary homogeneous nucleation, Brownian coagulation, condensation, and thermophoresis. The parameterization model is utilized for nucleation. The measured data for Beijing’s particle size distribution under both polluted and nonpolluted conditions are utilized as background particles. The relationship between the macroscopic measurement results and the microscopic dynamic process is analyzed by comparing the variation trend of several physical quantities in the process of aerosol evolution. It is found with an increase of background particle concentration, the nucleation is inhibited, which is consistent with the existing studies. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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14 pages, 3444 KiB  
Article
Effects of Velocity and Permeability on Tracer Dispersion in Porous Media
by Yulong Yang, Tongjing Liu, Yanyue Li, Yuqi Li, Zhenjiang You, Mengting Zuo, Pengxiang Diwu, Rui Wang, Xing Zhang and Jinhui Liang
Appl. Sci. 2021, 11(10), 4411; https://0-doi-org.brum.beds.ac.uk/10.3390/app11104411 - 13 May 2021
Cited by 7 | Viewed by 2280
Abstract
During micro-scale tracer flow in porous media, the permeability and fluid velocity significantly affect the fluid dispersion properties of the media. However, the relationships between the dispersion coefficient, permeability, and fluid velocity in core samples are still not clearly understood. Two sets of [...] Read more.
During micro-scale tracer flow in porous media, the permeability and fluid velocity significantly affect the fluid dispersion properties of the media. However, the relationships between the dispersion coefficient, permeability, and fluid velocity in core samples are still not clearly understood. Two sets of experiments were designed to study the effects of tracer fluid flow velocity and porous medium permeability on the dispersion phenomenon in a core environment, using natural and sand-filled cores, respectively. From experimental data-fitting by a mathematical model, the relationship between the dispersion coefficient, flow velocity, and permeability was identified, allowing the analysis of the underlying mechanism behind this phenomenon. The results show that a higher volumetric flow rate and lower permeability cause a delay in the tracer breakthrough time and an increase in the dispersion coefficient. The core experimental results show that the dispersion coefficient is negatively correlated with the permeability and positively correlated with the superficial velocity. The corresponding regression equations indicate linear relations between the dispersion coefficient, core permeability, and fluid velocity, resulting from the micron scale of grain diameters in cores. The combination of high velocity and low permeability yields a large dispersion coefficient. The effects of latitudinal dispersion in porous media cannot be ignored in low-permeability cores or formations. These findings can help to improve the understanding of tracer flow in porous media, the design of injection parameters, and the interpretation of tracer concentration distribution in inter-well tracer tests. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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15 pages, 2881 KiB  
Article
Profile Control Using Fly Ash Three-Phase Foam Assisted by Microspheres with an Adhesive Coating
by Yulong Yang, Tingting Cheng, Zhenjiang You, Tuo Liang and Jirui Hou
Appl. Sci. 2021, 11(8), 3616; https://0-doi-org.brum.beds.ac.uk/10.3390/app11083616 - 16 Apr 2021
Cited by 3 | Viewed by 1369
Abstract
Foam-assisted steam flooding is a promising technique to alleviate gas channeling and enhance sweep efficiency in heterogeneous heavy-oil reservoirs. However, long-term foam stabilization remains problematic at high temperatures. Three-phase foam (TPF), containing dispersed solid particles, has been proposed to improve foam stability under [...] Read more.
Foam-assisted steam flooding is a promising technique to alleviate gas channeling and enhance sweep efficiency in heterogeneous heavy-oil reservoirs. However, long-term foam stabilization remains problematic at high temperatures. Three-phase foam (TPF), containing dispersed solid particles, has been proposed to improve foam stability under harsh reservoir conditions. We fabricated a novel TPF system by adding ultrafine fly ash particles, as well as high-temperature resistant microspheres with an adhesive coating layer. This work aims at assessing the ability of the generated TPF in controlling steam channeling and enhancing oil recovery. Static and core flood tests were performed to evaluate foam strength and stability. Our results suggested a stronger foamability at a lower consolidation agent concentration, while a longer half-life period of foam and settling time of solid particles at a larger consolidation agent concentration were observed. Bubbles suspended independently in the liquid phase, with sizes varying from 10 to 100 μm, smaller than that of the conventional foam, suggesting a significant enhancement of foam dispersity and stability. The plugging rate was close to 90% when the temperature was as high as 300 °C, demonstrating a well-accepted plugging effect under high temperatures. A larger pore volume injection of TPF yielded a higher EOR in parallel cores, which substantiated the effectiveness of the three-phase foam system in sealing high-permeability channels. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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14 pages, 6742 KiB  
Article
Distribution and Deposition of Cylindrical Nanoparticles in a Turbulent Pipe Flow
by Wenqian Lin, Ruifang Shi and Jianzhong Lin
Appl. Sci. 2021, 11(3), 962; https://0-doi-org.brum.beds.ac.uk/10.3390/app11030962 - 21 Jan 2021
Cited by 6 | Viewed by 1619
Abstract
Distribution and deposition of cylindrical nanoparticles in a turbulent pipe flow are investigated numerically. The equations of turbulent flow including the effect of particles are solved together with the mean equations of the particle number density and the probability density function for particle [...] Read more.
Distribution and deposition of cylindrical nanoparticles in a turbulent pipe flow are investigated numerically. The equations of turbulent flow including the effect of particles are solved together with the mean equations of the particle number density and the probability density function for particle orientation including the combined effect of Brownian and turbulent diffusion. The results show that the distribution of the particle concentration on the cross-section becomes non-uniform along the flow direction, and the non-uniformity is reduced with the increases of the particle aspect ratio and Reynolds number. More and more particles will align with their major axis near to the flow direction, and this phenomenon becomes more obvious with increasing the particle aspect ratio and with decreasing the Reynolds number. The particles in the near-wall region are aligned with the flow direction obviously, and only a slight preferential orientation is observed in the vicinity of pipe’s center. The penetration efficiency of particle decreases with increasing the particle aspect ratio, Reynolds number and pipe length-to-diameter ratio. Finally, the relationship between the penetration efficiency of particle and related synthetic parameters is established based on the numerical data. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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Review

Jump to: Editorial, Research

23 pages, 4554 KiB  
Review
Heat Transfer Enhancement of Nanofluids with Non-Spherical Nanoparticles: A Review
by Xiaoyin Li, Fangyang Yuan, Wenma Tian, Chenlong Dai, Xinjun Yang, Dongxiang Wang, Jiyun Du, Wei Yu and Huixin Yuan
Appl. Sci. 2022, 12(9), 4767; https://0-doi-org.brum.beds.ac.uk/10.3390/app12094767 - 09 May 2022
Cited by 16 | Viewed by 2262
Abstract
This article reviews the heat transfer enhancement of nanofluids with non-spherical nanoparticles. We divided the non-spherical nanoparticles suspended in nanofluids into three categories based on the dimension of geometric particle structure. Based on the measured data in experimental studies, we then evaluated the [...] Read more.
This article reviews the heat transfer enhancement of nanofluids with non-spherical nanoparticles. We divided the non-spherical nanoparticles suspended in nanofluids into three categories based on the dimension of geometric particle structure. Based on the measured data in experimental studies, we then evaluated the shape effect of non-spherical nanoparticles on thermal conductivity and convective heat transfer enhancement of nanofluids. Recent studies explored the numerical predictions and related heat transfer mechanisms. Due to large aspect ratios, thermal conductivity is abnormally enhanced only for nanofluids with carbon nanotubes/nanofibers/nanowires. The approximate enhancement effect exerted by three types of non-spherical nanoparticles on thermal conductivity was 4.5:2.5:1. Thermal conductivity enhancement per concentration was larger for nanorods/ellipsoids with small aspect ratios. The convective heat transfer coefficient was increased by suspending non-spherical nanoparticles in the base fluid. Consequently, no significant thermohydraulic performance was discovered for convective heat transfer of non-spherical nanoparticle nanofluid flow, specifically for turbulent flows, due to increased pumping power. However, the temperature and particle concentration effect on convective heat transfer remains unclear. In addition, no perfect model for predicting the thermal conductivity and convective heat transfer of non-spherical nanoparticle nanofluids has been reported. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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10 pages, 2600 KiB  
Review
A Review on the Some Issues of Multiphase Flow with Self-Driven Particles
by Chen Liu and Jianzhong Lin
Appl. Sci. 2021, 11(16), 7361; https://0-doi-org.brum.beds.ac.uk/10.3390/app11167361 - 10 Aug 2021
Cited by 2 | Viewed by 1825
Abstract
Multiphase flow with self-driven particles is ubiquitous and complex. Exploring the flow properties has both important academic meaning and engineering value. This review emphasizes some recent studies on multiphase flow with self-driven particles: the hydrodynamic interactions between self-propelled/self-rotary particles and passive particles; the [...] Read more.
Multiphase flow with self-driven particles is ubiquitous and complex. Exploring the flow properties has both important academic meaning and engineering value. This review emphasizes some recent studies on multiphase flow with self-driven particles: the hydrodynamic interactions between self-propelled/self-rotary particles and passive particles; the aggregation, phase separation and sedimentation of squirmers; the influence of rheological properties on its motion; and the kinematic characteristics of axisymmetric squirmers. Finally, some open problems, challenges, and future directions are highlighted. Full article
(This article belongs to the Special Issue Multiphase Flows in Microfluidics: Fundamentals and Applications)
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