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EVOLUTION OF NUMBER CONCENTRATION OF NANO-PARTICLES UNDERGOING BROWNIAN COAGULATION IN THE TRANSITION REGIME

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Journal of Hydrodynamics 2011年第4期23卷 416-421页

作者： WANG Yu-ming LIN Jian-zhong Institute of Fluid Measurement and Simulation China Jiliang University Hangzhou 310018 China china jiliang university Hangzhou 310018 China State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

Evolution of number concentration of nanoparticles undergoing Brownian coagulation in the transition regime is studied theoretically and numerically. The results show that the curves of particle size distribution move toward the area with large particle diameters, the curve peak becomes lower and the range that particle diameters cover becomes wider as time elapses. In the process of coagulation the particles with small diameter disappear gradually and the particle size distribution remains a log-normal distribution. The change rate of the particle size distribution is more appreciable at the initial stage than that at the final stage. The initial Knudsen number has a significant effect on the coagulation rate which increases with decreasing the initial Knudsen number. The larger the initial geometric standard deviation is, the smaller the curve peak is, and the wider the area that curves cover is. The initial geometric standard deviation has a significant effect on the particle size distribution which can remain a self-preserving state when the initial geometric standard deviation is smaller than 2. With the increase of the diversity of initial particle size, the particle size distribution does not obey the log-normal distribution any more as time elapses.

关键词： nanoparticles Brownian coagulation number concentration numerical simulation

Transport and deposition of nanoparticles in bend tube with circular cross-section

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Progress in Natural Science:Materials International 2009年第1期19卷 33-39页

作者： Peifeng Lin a,Jianzhong Lin a,b,a State Key Laboratory of Fluid Power Transmission and Control,Zhejiang university,Hangzhou 310027,china b china jiliang university,Hangzhou 310018,china State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china jiliang university Hangzhou 310018 China

Transport and deposition of nanoparticles in bend tube with circular cross-section were simulated numerically for different Reynolds numbers and Dean numbers.A finite-volume code and the SIMPLE scheme were used to solve the *** results show that the distribution of nanoparticle concentration is symmetrical with respect to the top and bottom sides of the *** diameter of the nanoparticles has a weak effect on the distribution of nanoparticle *** maximum and minimum of the deposition enhancement factor occur near the outside and inside walls of the bend tube,*** higher the Reynolds number is,the shorter is the time for nanoparticle *** bend curvature radius has a slight effect on the deposition enhancement factor.

关键词： Nanoparticles Transport Deposition Numerical simulation

A theoretical model of turbulent fiber suspension and its application to the channel flow

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1659-1670页

作者： LIN JianZhong1,2 & SHEN SuHua1 1 Department of Mechanics,Zhejiang university,Hangzhou 310027,china 2 china jiliang university,Hangzhou 310018,china Department of Mechanics Zhejiang University Hangzhou China china jiliang university Hangzhou China

A theoretical model of turbulent fiber suspension is developed by deriving the equations of Reynolds averaged Navier-Stokes,turbulence kinetic energy and turbulence dissipation rate with the additional term of *** order to close the above equations,the equation of probability distribution function for mean fiber orientation is also *** theoretical model is applied to the turbulent channel flow and the corresponding equations are solved *** numerical results are verified by comparisons with the experimental *** effects of Reynolds number,fiber concentration and fiber aspect-ratio on the velocity profile,turbulent kinetic energy and turbulent dissipation rate are *** on the numerical data,the expression for the velocity profile in the turbulent fiber suspension channel flow,which includes the effect of Reynolds number,fiber concentration and aspect-ratio,is proposed.

关键词： theoretical model turbulent fiber suspension numerical simulation channel flow modification of velocity profile

Lp-dual Quermassintegral sums

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Science china Mathematics 2007年第9期50卷 1347-1360页

作者： Chang-jian ZHAO Department of Information and Mathematics Sciences,College of Science,china jiliang university,Hangzhou 310018,china Department of Information and Mathematics Sciences College of Science China Jiliang University Hangzhou China

In this paper,we first introduce a concept of L_p-dual Quermassintegral sum function of convex bodies and establish the polar projection Minkowski inequality and the polar projection Aleksandrov-Fenchel inequality for L_p-dual Quermassintegral ***,by using Lutwak’s width-integral of index i,we establish the L_p-Brunn-Minkowski inequality for the polar mixed projec- tion *** applications,we prove some interrelated results.

关键词： mixed volumes mixed projection bodies dual Quermassintegral sum polar of mixed projection bodies 52A40 53A15

PARTICLE SIZE DISTRIBUTION IN A PLANAR JET FLOW UNDER-GOING SHEAR-INDUCED COAGULATION AND BREAKAGE

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Journal of Hydrodynamics 2010年第4期22卷 445-455页

作者： GAN Fu-jun LIN Jian-zhong YU Ming-zhou State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china jiliang university Hangzhou 310018 China State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china jiliang university Hangzhou 310018 China

A CFD simulation is performed for a particle-laden planar jet *** Reynolds number is 8300,and the initial particle diameter is 1 μ*** Eddy Simulation（LES） is employed to calculate the flow field,and the Taylor-series expansion moment method（TEMOM） is adopted to deal with the balance equation of particle coagulation and *** shear-induced coagulation kernel,power-law breakage kernel and symmetric fragment distribution function are *** prediction of the distribution of the mean streamwise velocity of the jet is in good agreement with experimental *** evolution of particle number concentration,volume concentration,polydispersity,particle diameter and standard geometric deviation is discussed in *** results show that as the jet travels downstream,the particle number concentration and volume concentration decrease,while their spans become *** polydispersity and particle diameter are very large in the shear layers at the upstream and in the core of vortex structures at the *** particle standard geometric deviation changes within the range of 1.32 ≤σg≤ 1.96,and increases sharply in the shear *** variables approach the steady-state as time progresses.

关键词： Taylor-series expansion moment method shear-induced coagulation breakage planar jet

Numerical research on the 3D fiber orientation distribution in arbitrary planar flows

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Progress in Natural Science:Materials International 2007年第11期17卷 1357-1362页

作者： Zhou Kun1 and Lin Jianzhong1,2(1. State Key Laboratory of Fluid Power Transmission and Control, Zhejiang university, Hangzhou 310027, china 2. china jiliang university, Hangzhou 310018, china) State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china jiliang university Hangzhou 310018 China

The fiber orientation distribution in a fiber suspension flow was investigated by a finite difference scheme in spherical coordinates. The diffusivity was transformed between Cartesian and spherical coordinates through tensor analysis to obtain efficiency. It is found that under simple shear flow condition the diffusivity in the azimuthal direction, Dr, has greater effect on the orientation distribution than that in the colatitude direction, Drθθ.

关键词： fiber suspension flow orientation distribution diffusivity

NUMERICAL SIMULATION OF NANOPARTICLE COAGULATION IN A POISEUILLE FLOW VIA A MOMENT METHOD

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Journal of Hydrodynamics 2008年第1期20卷 1-9页

作者： LIU Song LIN Jian-zhong State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china Jiiiang university Hangzhou 310018 China

Numerical simulations of coagulating nano-scale aerosols in a two dimensional Poiseuille flow between fixed plates are performed. Evolution of the particle field is obtained by utilizing a moment method to approximate the aerosol general dynamic equation. A moment method is used, which assumes a lognormal function for the particle size distribution and requires knowledge of the first three moments. A Damk？hler number is defined to represent the ratio of the convection time scale to the coagulation time scale. Simulations are performed based on three Reynolds numbers, 100, 500 and 1000, and on three initial particle volume fractions corresponding to Damk？hler numbers 0.1, 0.2 and 1.0. Spatio-temporal evolution of the first three moments along with the geometric mean volume and standard deviation are discussed.

关键词： nanoparticle Coagulation moment method Poiseuille flow

Numerical simulation of the efficiency of mixing in heterogeneous microchannels with patterned surface potentials

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Progress in Natural Science:Materials International 2006年第12期16卷 1322-1328页

作者： ZHANG Kai~1, LIN Jianzhong~ 1,2 ** and LI Huijun~1(1. State Key Laboratory of Fluid Power Transmission and Control, Zhejiang university, Hangzhou 310027, china 2. china jiliang university, Hangzhou 310018, china) State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china jiliang university Hangzhou 310018 China

The mixing of samples in heterogeneous microchannels with a periodically stepwise surface potential was analyzed numerically using the control volume method. The equations describing the wall potential and external potential were solved first to get the distribution of wall potential and external potential, respectively, then the momentum equation was solved to get the developed flow field. Finally, the mass transport equation was solved to get the concentration field. The simulation results show that the distribution of samples at the inlet of the microchannel determines its theoretical value of concentration, therefore, the pattern of the distribution of samples at the inlet and its corresponding velocity can be changed to get the desirable concentration of solute. The heterogeneous wall potential almost has no effect on the mixing of samples in two-inlet microfluidic devices. For three-inlet microfluidic devices, the comprehensive ability of transportation and mixing has an optimization when the ratio of periodic length of wall potential to the height of the microchannel is about 4.88. The above conclusions are helpful to the optimization of the design of microfluidic devices.

关键词： microchannel mixing efficiency electroosmosis numerical simulation.

NUMERICAL SIMULATION OF THE FORMATION OF NANOPARTICLES IN AN IMPINGING TWIN-JET

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Journal of Hydrodynamics 2007年第5期19卷 533-541页

作者： YIN Zhao-qin LIN Jian-zhong Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China china jiliang university Hangzhou 310018 China

The Large Eddy Simulation （LES） method has been used to solve the fluid momentum equations coupled with a convection,liffusion equation to study the formation of pollutant nanoparticles in a vehicular exhaust with impinging twin-jet. The functions of the space （S） between the two jets and the distance （H） from the exit of nozzle to the impingement plane are evaluated according to the distributions of pollutant nanoparticles. The results show that the nucleation produces a large number of nanoparticles, and gas-to-nanoparticle conversion mostly takes place in the interface region of the two jets, the circumambience of the jets, and region near the plane. The maximal particle size and maximal number concentration produced by both nucleation and coagulation appear around the region of free jet and the region near the plane, respectively. The significant differences for various spaces between the two jets are the number concentration and size distributions in the interface region of the two jets. For the case with larger space, more nanoparticles are produced by nucleation and coagulation The more the distance from the exit of nozzle to the impingement plane, the lower is the fewer the particles distribute distance from nozzle to plane is nanoparticle formation. the number concentration and near the plane. Increasing the beneficial to the reduction of

关键词： pollutant nanoparticles vehicular exhaust,impinging twin-jet nucleation coagulation simulation