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Science Letters:Research on 3D fiber orientation distribution in arbitrary planar flows

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第7期8卷 1021-1025页

作者： ZHOU Kun lin jian-zhong State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China China Jiliang University Hangzhou 310018 China

A non-stretchable fiber rotation in planar flows has been solved. The fiber will rotate periodically or run to the asymptotical direction decided by a discriminant defined in the paper involving the fiber aspect ratio and the flow characteristics. Subsequently the fiber orientation distribution is derived directly without the bother of solving the Fokker-Planck equation. The research clearly indicates the overall configuration of a fiber rotation movement in planar flows.

关键词： Fiber suspension flow Jeffery orbit Fiber orientation distribution

WALL EFFECTS ON FLOWS PAST TWO TANDEM CYlinDERS OF DIFFERENT DIAMETERS

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Journal of Hydrodynamics 2012年第1期24卷 1-10页

作者： jianG Ren-jie lin jian-zhong State Key Laboratory of Fluid Power Transmission and Control Zhejiang UniversityHangzhou 310027China China Jiliang University Hangzhou 310018China

Flows past two tandem cylinders of different diameters placed centrally in a channel with fixed centre-to-centre spacing 6D and diameter ratio are simulated based on the Lattice Boltzmann Method（LBM）.In all the simulations,the diameter of the smaller cylinder is chosen as the characteristic *** Reynolds number based on the average inflow velocity is 20-120 and studies are over the range of blockage ratio *** both Small-Big Arrangement（SBA）and Big-Small Arrangement（BSA）,the effects of the channel width and Reynolds number on the flow structures and force coefficients are *** show that the flows in BSA are more regular than those in SBA for the same flow *** BSA with and,the force coefficients all fluctuate with constant amplitudes and a coupled frequency,the coupled frequency becomes small as the blockage ratio decreases and by an exact test we give out the relation of the blockage ratio and Strouhal *** the blockage ratio decreases to 2,there exist pitchfork bifurcations in both SBA and BSA,and results show that the critical Reynolds numbers of pitchfork bifurcations for SBA and BSA are both between 60 and *** SBA with,the flow structure has a static asymmetric *** is found that the channel width has also an effect on the critical spacing where the flow changes from single body mode into co-shedding *** an accurate survey on flows past two cylinders with equal diameters placed inside a channel with the width,the relation between channel width and the critical spacing is given and results show that the critical spacing increases as the channel width increases.

关键词： two tandem cylinders different diameters blockage ratio critical spacing Lattice Boltzmann Method(LBM)

Effect of Coagulation and Diffusion on Nanoparticle Distribution in a Fully Developed Turbulent Boundary Layer

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Chinese Physics Letters 2012年第5期29卷 157-160页

作者： lin jian-zhong CHEN zhong-Li Department of Mechanics Zhejiang UniversityHangzhou 310027 Institute of Fluid Mechanics China Jiliang UniversityHangzhou 310018

Nanoparticle distributions in a fully developed turbulent boundary layer are simulated numerically using the moment *** effects of Schmidt number and Damk(o)hler number on the nanoparticle distribution are *** is found that the particle number concentration and total particle mass increase from the wall to the *** difference of particle number concentration and total particle mass near the wall and near the outside becomes smaller with the increasing Schmidt number *** particle diameter and geometric standard deviation increase from the wall to the outside at a fixed Damk(o)hler number Da,and grow with the increase of Da at the same lateral position.

关键词： particle outside Boundary

Properties of the Collision Efficiency of Nanoparticles in Brownian Coagulation

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Chinese Physics Letters 2011年第1期28卷 130-133页

作者： WANG Yu-Ming lin jian-zhong CHEN zhong-Li Institute of Fluid Mechanics China Jiliang University Hangzhou 310018 Department of Mechanics Zhejiang University Hangzhou 310027

The collision efficiency of nanoparticles with diameters from 100nm to 750nm in the Brownian coagulation is studied by building and solving＂ numerically the equations of particle collision in the presence of the van der Waals force, the elastic deformation force, the Stokes resistance, the lubrication force and the electrostatic force. The results show that the collision efficiency decreases overall with the increasing- particle diameter. It is found that there exists an abrupt increase in the collision efficiency when the particle diameter is equals to 550nm. Finally a new expression for the collision efficiency is presented.

关键词： Condensed matter: structural, mechanical & thermal Nanoscale science and low-D systems

DISCUSSION ON RELATION BETWEEN BOUNDARY LAYER AND WALL EROSION CAUSED BY STRIKING OF PARTICLES

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Journal of Hydrodynamics 1991年第1期3卷 72-76页

作者： lin, jian-zhong Shen, Tian-yao Zhejiang Univ Hangzhou China

The kinetic characteristics of particles moving through laminar or turbulent boundary layer are computed and different erosive situations caused by striking of particles are compared. The function of anti-erosion sinews added on the blades is analysed. The energy detrition in the two-phase turbulent flow is discussed. The content is helpful to the design of anti-erosion fans.

关键词： Erosion Fans Fluid Mechanics Mathematical Models Turbomachinery Blades

Sedimentation of short cylindrical pollutants with mechanical contacts

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Journal of Environmental Sciences 2005年第6期17卷 906-911页

作者： lin jian-zhong WANG Ye-long ZHANG Wei-feng Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China Institute of Marine and Coastal Sciences Rutgers University New Brunswick New Jersey USA

Lattice Boltzmann method and elastic particle collision model were used to investigate the sedimentation of short cylindrical pollutant particles with mechanical contacts for varying bulk number density ε and terminal Reynolds number ReT. The corresponding experiments were performed as a comparison. The clusters of pollutant particles with an inverted “T” structure were observed, the pollutant particles for high ε and large ReT scattered wider than that for low ε and small ReT. The sedimentation velocities increased suddenly at the initial stage, then decreased drastically, after that swayed around and approached to a steady value. The time to steady state did not depend on ε and ReT. The effect of particle interactions was to hinder the average sedimentation velocity, and hindrance was directly proportional to ε. The orientation distributions of pollutant particles depended on ReT and ε, especially on the former. Both the standard deviations of vertical and horizontal velocity, the former was larger than the latter, were nearly independent on ε and ReT.

关键词： cylindrical pollutant particles sedimentation lattice-Boltzmann simulation experiment mechanical contact

RESEARCH ON THE FLOW PROPERTY IN THREE DIMENSIONAL CAVITY OF MICRO-CHANNEL

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Journal of Hydrodynamics 2006年第1期18卷 20-25页

作者： BAO Fu-bing lin jian-zhong LIU Yan-hua Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China China Jiliang University Hangzhou 310018 China

The vortical property in a three dimensional cavity of micro-channel flow, which is very important, was investigated numerically. The results show that the rotation direction of vortex in the cavity depends on the dimension and shape of the cavity as well as the viscosity of the fluid. With the dimension and shape of the cavity fixed, there exists a critical inlet velocity. When the inlet velocity is less than the critical value, the rotation direction of vortex in the cavity will change. The critical velocity is directly proportional to the vis- cosity of the fluid, and inversely proportional to square of the thickness, length and depth of cavity. For the ratio of length and depth of cavity equals to one, there is a critical dimensionless parameter Recr , when Recr＇ is less than Recr＇ , the rotation direction of vortex will change too. Recr＇ is equal to 11.8 approximately.

关键词： micro channel cavity flow vortex numerical simulation

ON INSTABILITY OF DILUTE FIBER SUSPENSIONS IN AN AXISYMMETRIC TAYLOR-COUETTE FLOW

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Journal of Hydrodynamics 2005年第4期17卷 398-403页

作者： WAN Zhan-hong lin jian-zhong LI Bing-ru Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China

A stability analysis of flow between two coaxial rotating cylinders in the presence of fibers was performed. Based on the axisymmetric normal mode for the disturbances, a modified stability equation was derived. Then the numerical solution of the eigenvalue problem about the equation was obrained using the fourth order finite difference scheme. The marginal curves that determine the instability property were drawn. The results show that the flow instability of the dilute fiber suspensions is governed by the aspect ratio of fiber H, the inerement of H causes an increase of critical inner Reynohts number. The fiber additives effectively attenuate the instability of the flow. which is in agreement with those of related experiments.

关键词： linear stability fiber suspensions Taylor-Couette flow numerical simulation

On the hydrodynamic stability of a particle-laden flow in growing flat plate boundary layer

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第2期8卷 275-284页

作者： XIE Ming-liang lin jian-zhong XING Fu-tang Department of Mechanics State Key Laboratory of Fluid Power Transmission and Control Zhejiang University Hangzhou 310027 China College of Metrology Technology and Engineering China Jiliang University Hangzhou 310018 China Department of Environment Engineering Wuhan University of Science and Technology Wuhan 430081 China

The parabolized stability equation (PSE) was derived to study the linear stability of particle-laden flow in growing Blasius boundary layer. The stability characteristics for various Stokes numbers and particle concentrations were analyzed after solving the equation numerically using the perturbation method and finite difference. The inclusion of the nonparallel terms produces a reduction in the values of the critical Reynolds number compared with the parallel flow. There is a critical value for the effect of Stokes number, and the critical Stokes number being about unit, and the most efficient instability suppression takes place when Stokes number is of order 10. But the presence of the nonparallel terms does not affect the role of the particles in gas. That is, the addition of fine particles (Stokes number is much smaller than 1) reduces the critical Reynolds number while the addition of coarse particles (Stokes number is much larger than 1) enhances it. Qualitatively the effect of nonparallel mean flow is the same as that for the case of plane parallel flows.

关键词： Hydrodynamic stability Blasius boundary layer Particle-laden nonparallel flow Numerical simulation