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A review on the flow instability of nanofluids

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Applied Mathematics and Mechanics(English Edition) 2019年第9期40卷 1227-1238页

作者： jianzhong lin Hailin YANG Department of Mechanics State Key Laboratory of Fluid Power and Mechatronic SystemsZhejiang University

Nanofluid flow occurs in extensive applications, and hence has received widespread attention. The transition of nanofluids from laminar to turbulent flow is an important issue because of the differences in pressure drop and heat transfer between laminar and turbulent flow. Nanofluids will become unstable when they depart from the thermal equilibrium or dynamic equilibrium state. This paper conducts a brief review of research on the flow instability of nanofluids, including hydrodynamic instability and thermal instability. Some open questions on the subject are also identified.

关键词： nanofluid thermal instability hydrodynamic instability review

A review of research on nanoparticulate flow undergoing coagulation

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Acta Mechanica Sinica 2015年第3期31卷 292-302页

作者： jianzhong lin linlin Huo Institute of Fluid Measurement and Simulation China Jiliang University Institute of Fluid Engineering Zhejiang University

Nanoparticulate flows occur in a wide range of natural phenomena and engineering applications and, hence, have attracted much attention. The purpose of the present paper is to provide a review of the research conducted over the last decade. The research covered relates to the Brownian coagulation of monodisperse and polydisperse particles, the Taylor-series expansion method of moment, and nanoparticle distributions due to coagulation in pipe and channel flow, jet flow, and the mixing layer and in the process of flame synthesis and deposition.

关键词： Nanoparticulate flow Coagulation Review

Swimming velocity of spherical squirmers in a square tube at finite fluid inertia

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1481-1498页

作者： Tongxiao JIANG Deming NIE jianzhong lin Institute of Fluid Mechanics China Jiliang UniversityHangzhou 310008China Key Laboratory of Impact and Safety Engineering(Ningbo University) Ministry of EducationNingbo 315211China Institute of Fluid Engineering Zhejiang UniversityHangzhou 310027China

The three-dimensional lattice Boltzmann method(LBM)is used to simulate the motion of a spherical squirmer in a square tube,and the steady motion velocity of a squirmer with different Reynolds numbers(Re,ranging from 0.1 to 2)and swimming types is investigated and analyzed to better understand the swimming characteristics of microorganisms in different ***,as the Reynolds number increases,the effect of the inertial forces becomes significant,disrupting the squirmer's ability to maintain its theoretical ***,as the Reynolds number increases,the structure of the flow field around the squirmer changes,affecting its velocity of ***,the swimming velocity of the squirmer exhibits a quadratic relationship with the type of swimming and the Reynolds ***,the narrow tube exerts a significant inhibitory effect on the squirmer *** addition,although chirality does not directly affect the swimming velocity of the squirmer,it can indirectly affect the velocity by changing its motion mode.

关键词： spherical squirmer swimming characteristics swimming velocity fow structure

Modeling on effervescent atomization:A review

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Science China(Physics,Mechanics & Astronomy) 2011年第12期54卷 2109-2129页

作者： QIAN LiJuan lin jianzhong China Jiliang University Hangzhou 310018 China State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

The study and modeling process of effervescent atomization are reviewed. The mechanism of droplet events and the treatment of liquid fragmentation process and dispersed particles are systematically presented, which includes the primary atomization of Newtonian and non-Newtonian fluid, instability analysis, turbulence treatment, particle tracking, secondary atomization and droplets collision. The review on the sub-models involved in the simulation of effervescence is followed by a summary of the achievements of modeling. First is the validation of models; then the parametric study is summarized; the third part introduces the fitting formula of droplet mean size and impinging factors, and finally the scope of future study is indicated.

关键词： effervescent atomization spray modeling review

A modified TEMOM model for Brownian coagulation of nanoparticles based on the asymptotic solution of the sectional method

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Science China(Technological Sciences) 2013年第12期56卷 3081-3092页

作者： lin jianzhong CHEN ZhongLi School of Aeronautics and Astronautics Zhejiang University China Jiliang University

The Taylor-series expansion method of moments(TEMOM)is modified to match the behavior of real self-preserved aerosols by taking advantage of the numerical results obtained by the sectional method for Brownian coagulation in both continuum and free molecular *** newly proposed model is able to predict the evolution of the zeroth and second moments more accurately than the original TEMOM when the aerosol size distribution approaches self-preserving or the coagulation time is sufficiently long.A special kind of coordinate diagram,which describes the relationship between the moment equations and one non-dimensional moment is first used to investigate different methods of moments that only involve the first three *** errors produced by different methods of moments can be qualitatively explained by these *** polynomial fitting,a new set of moment equations for Brownian coagulation in the free molecular regime is proposed in the framework of the log-normal preserving theory.

关键词： nanoparticles Brownian coagulation method of moments sectional method

EFFECT　OF　SOLID　PARTICLES　ON　STABILITY　FLOW　IN　THE　BOUNDARY　LAYER　ON　A　FLAT　PLATE

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Journal of Hydrodynamics 1996年第2期8卷 35-41页

作者： lin, jianzhong Zhou, Zexuan Zhejiang Univ Hangzhou China

The stability of flow with suspended solid particles has been examined by analyzing the expanded Ors-Sommerfeld equation.A series of numerical simulations varying particle size, particle loading, particle density and ratio of particle velocity to fluid velocity have been conducted. The results show that smaller particles and lighter particles will make instability easier. Increasing ratio of particle velocity to fluid velocity is found to be a destabilizing mechanism. The instability is enhanced as the particle loading increases.

关键词： boundary layer particles numerical simulation

Mixture flow of particles and power-law fluid in round peristaltic tube

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Applied Mathematics and Mechanics(English Edition) 2019年第6期40卷 805-822页

作者： Hailin YANG jianzhong lin Xiaoke KU Institute of Fluid Engineering School of Aeronautics and AstronauticsZhejiang University

The erythrocyte and blood flowing in the blood vessel can be treated as the two-phase flow of the mixture of particles and a power-law fluid in a peristaltic *** the present work, the peristaltic transport of a power-law fluid and the suspension of particles in a tube is investigated by a perturbation method using the long wavelength approximation. The influence of different parameters on the velocity profile and streamlines is explored. Results show that there is a deflection of the flow field when the power-law index n = 0.5 or 1.5 compared with the Newtonian fluid where the trapping zone is symmetric to a certain cross section. The flux rate and reflux of the material are identified,and the conditions under which the reflux appears are determined. Moreover, a reflux phenomenon occurs near the wall. The trapping zone is related to not only the tube geometry and the flow flux but also the fluid properties. Both the length and width of the trapping zone increase with an increase in θ or φ. The trapping zone is more difficult to produce in the shear-thinning fluid than the shear-thickening fluid.

关键词： peristaltic transport two-phase flow power-law fluid perturbation method trapping phenomenon

Nanoparticle distribution in a rotating curved pipe considering coagulation and dispersion

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Science China(Physics,Mechanics & Astronomy) 2011年第8期54卷 1502-1513页

作者： lin jianzhong lin PeiFeng CHEN HuaJun Department of Mechanics Zhejiang University Hangzhou 310027 China China Jiliang University Hangzhou 310018 China Department of Mechanical Engineering University of Nevada Las Vegas NV 89154 USA

We study the evolution of the particle number concentration, mass concentration, particle polydispersity, particle diameter and geometric standard deviation considering particle coagulation and dispersion in a rotating curved pipe at different Reynolds number, Schmidt number and F number. It is found that, when the Coriolis force and the centrifugal force point to the same direction, particles concentrate near the outside edge of the pipe, which becomes more obvious as time goes by. The particle number and mass concentration increase faster at the early stage than that at the later stage, and approach a stable value finally. As the coagulation proceeds, the particle diameter, polydispersity and geometric standard deviation increase and have high values in the region close to the outside edge of the pipe. When the Coriolis force and the centrifugal force point to the oppo- site direction and the Coriolis force is more dominant than the centrifugal force, particles concentrate near the inside edge of the pipe. The particles in the region with a high number concentration have high mass concentration, large diameter and high polydispersity as well as large geometric standard deviation. The particle distribution is dependent on the balance of the pipe curvature and rotating speed. The Reynolds number and the Schmidt number have effects on the particle distribution when other parameters remain unchanged. An increase in the Reynolds number leads to an increase in particle number concentration and mass concentration, and a decrease in particle polydispersity, particle diameter and geometric standard deviation. With the increase of Schmidt number the particle number concentration and mass concentration increase, and the particle polydispersity, particle diameter and geometric standard deviation decrease.

关键词： nanoparticles coagulation rotating curved pipe numerical simulation

Asymptotic behavior of the Taylor-expansion method of moments for solving a coagulation equation for Brownian particles

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Particuology 2014年第3期12卷 124-129页

作者： Zhongli Chen jianzhong lin Mingzhou Yu Zhejiang University China Jiliang University

The evolution equations of moments for the Brownian coagulation of nanoparticles in both continuum and free molecule regimes are analytically studied. These equations are derived using a Taylor-expansion technique. The self-preserving size distribution is investigated using a newly defined dimensionless parameter, and the asymptotic values for this parameter are theoretically determined. The dimensionless time required for an initial size distribution to achieve self-preservation is also derived in both regimes. Once the size distribution becomes self-preserving, the time evolution of the zeroth and second moments can be theoretically obtained, and it is found that the second moment varies linearly with time in the continuum regime. Equivalent equations, rather than the original ones from which they are derived, can be employed to improve the accuracy of the results and reduce the computational cost for Brownian coagulation in the continuum regime as well as the free molecule regime.

关键词： Brownian particles Coagulation Size distribution Accuracy