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Mixed convection flow of jeffrey nanofluid with thermal radiation and double stratification

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Journal of Hydrodynamics 2016年第5期28卷 840-849页

作者： f.M.ABBASI S.A.SHEHZAD t.HAYAt M.S.ALHUtHALI Department of Mathematics COMSATS Institute of Information Technology Islamabad Department of Mathematics Comsats Institute of Information Technology Department of Mathematics Quaid-i-Azam University Nonlinear Analysis and Applied Mathematics (NAAM) Research Group Department of MathematicsFaculty of ScienceKing Abdulaziz University

this article addresses the two-dimensional laminar boundary layer flow of magnetohydrodynamic （MHD） Jeffrey nano- fluid with mixed convection. Effects of thermal radiation, thermophoresis, Brownian motion and double stratifications are taken into account. Rosseland＇s approximation is utilized for the thermal radiation phenomenon. Convergent series solutions of velocity, tempe- rature and nanoparticle concentration are developed. Graphs of dimensionless temperature and nanoparticle concentration are prese- nted to investigate the influences of different emerging parameters. the values of skin-friction coefficient, local Nusselt and Sherwood numbers are computed and discussed for both Jeffrey and viscous fluids cases. We have observed that the temperature profile retarded for the larger values of Deborah number while an enhancement is noticed with the increasing values of ratio of relaxation to retardation times. Increasing values of thermal and nanoparticle concentration stratifications lead to a reduction in the temperature and nanoparticle concentration. the values of local Nusselt and Sherwood numbers are larger for the viscous fluid case when compared with Jeffrey fluid.

关键词： MHD flow Jeffrey nanofluid double stratification thermal radiation mixed convection

tHE INtERfACIAL BEHAVIORS Of ALUMINUM MAtRIX COMPOSItE IN DIffERENt WELDING MEtHODS

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Acta Metallurgica Sinica(English Letters) 2004年第1期17卷 55-60页

作者： W.Guo J.t.Niu J.f.Zhai G.t.Zhou M.Z.Wang State Key Laboratory of Advanced Welding Production technology Harbin Institute of Technology(HIT)Harbin150001China State Key Laboratory of Metal Matrix Composite Shanghai Jiaotong University.Shanghai 200030.China

Non-interlayer liquid phase diffusion welding (China Patent) and laser welding methods for aluminum matrix composite are mainly described in this paper. In the non-interlayer liquid phase diffusion welding, the key processing parameters affecting the strength of joint is welding temperature. When temperature rises beyond solidus temperature, the bonded line vanishes. the strength of joint reaches the maximum and becomes constant when welding temperature is close to liquid phase temperature. Oxide film in the interface is no longer detected by SEM in the welded joint. With this kind of technique, particle reinforced aluminum matrix composite Al2 O3p/6061Al is welded successfully, and the joint strength is about 80% of the strength of composite (as-casted). In the laser welding, results indicate that because of the huge specific surface area of the reinforcement, the interfacial reaction between the matrix and the reinforcement is restrained intensively at certain laser power and pulsed laser beam. the laser pulse frequency directly affects the reinforcement segregation and the reinforcement distribution in the weld, so that the weldability of the composite could be improved by increasing the laser pulse frequency. the maximum strength of the weld can reach 70% of the strength of the parent.

关键词： non-interlayer liquid phase diffusion welding Al2O3p/6061 Alaluminum matrix composite laser welding interface behavior reinforcement

Solid state crack repair by friction stir processing in 304L stainless steel

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Journal of Materials Science & technology 2018年第1期34卷 140-147页

作者： C.Gunter M.P.Miles f.C.Liu t.W Nelson Manufacturing Engineering technology Brigham Young University Department of Mechanical Engineering Brigham Young University

friction stir processing （fSP） was investigated as a method of repairing cracks in 12 mm thick 304L stainless steel plate. Healing feasibility was demonstrated by processing a tapered crack using a PCBN/W- Re tool with a 25 mm diameter shoulder and a pin length of 6.4 mm. the experiment showed that it was possible to heal a crack that begins narrow and then progressively grows up to a width of 2 mm. Bead on plate experiments were used to find the best parameters for creating a consolidated stir zone with the least amount of hardness difference compared to the base metal. Grain refinement in some specimens resulted in much higher stir zone hardness, compared to base metal, A plot of grain size versus microhardness showed a very strong inverse correlation between grain size and hardness, as expected from the Hall- Perch relationship. Corrosion testing was carried out in order to evaluate the effect of fSP on potential sensitization of the stir zone. After 1000 h of intermittent immersion in 3.5% saline solution at room temperature it was found that no corrosion products formed on the base material controls or on any of the friction stir processed specimens.

关键词： Stainless steel Crack healing friction stir processing Corrosion resistance

Structure Heterogeneity in Metallic Glass: Modeling and Experiment

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Journal of Materials Science & technology 2014年第6期30卷 560-565页

作者： H.B.Ke J.f.Zeng C.t.Liu Y.Yang Centre for Advanced Structural Materials Department of Mechanical and Biomedical EngineeringCity University of Hong Kong

Despite the great efforts dedicated to metallic glasses （MGs）, their structure still remains a mystery to be understood. With comparison to the existing mJciomechanical models, such as the free-volume and shear transformation zone （StZ） models, we first discuss in this article our recently proposed ＇core-shell＇ model, which contains a solid-like matrix and liquid-like inclusions. this serves as the theoretical basis to understand the structural heterogeneity in MGs in our analytical framework. After that, a scanning ultrafast nanoindentation technique is used to map out the structure heterogeneity in a Zr-based bulk metallic glass （BMG）. With these ongoing research efforts, we hope that more research work could be stimulated in the pursuit of the structure-property relation in MGs.

关键词： Metallic glass Structure heterogeneity Nanoindentation Core-shell model

Application of particle splitting method for both hydrostatic and hydrodynamic cases in SPH

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Acta Mechanica Sinica 2018年第4期34卷 601-613页

作者： W.t.Liu P.N.Sun f.R.Ming A.M.Zhang College of Shipbuilding Engineering Harbin Engineering University

Smoothed particle hydrodynamics（SPH） method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction problems. However, in most simulations, uniform particle distributions are used and the multi-resolution, which can obviously improve the local accuracy and the overall computational efficiency, has seldom been applied. In this paper, a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic problems. the splitting algorithm is that, when a coarse（mother） particle enters the splitting region, it will be split into four daughter particles, which inherit the physical parameters of the mother particle. In the particle splitting process,conservations of mass, momentum and energy are ensured. Based on the error analysis, the splitting technique is designed to allow the optimal accuracy at the interface between the coarse and refined particles and this is particularly important in the simulation of hydrostatic cases. finally, the scheme is validated by five basic cases, which demonstrate that the present SPH model with a particle splitting technique is of high accuracy and efficiency and is capable for the simulation of a wide range of hydrodynamic *** particle hydrodynamics（SPH）method with numerical diffusive terms shows satisfactory stability and accuracy in some violent fluid–solid interaction ***,in most simulations,uniform particle distributions are used and the multi-resolution,which can obviously improve the local accuracy and the overall computational efficiency,has seldom been *** this paper,a dynamic particle splitting method is applied and it allows for the simulation of both hydrostatic and hydrodynamic *** splitting algorithm is that,when a coarse（mother）particle enters the splitting region,it will be split into four daughter particles,which inherit the physical parameters of the mother *** the pa

关键词： Smoothed particle hydrodynamics Particle splitting Particle refinement Solid wall boundary fluid–structure interaction

Real-time Measurements and Modelling on Dynamic Behaviour of SonoVue Bubbles Based on Light Scattering technology

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Chinese Physics Letters 2008年第1期25卷 172-175页

作者：屠娟 GUANJ.f. MAtULA t.J. Crum L.A. 魏荣爵 Key Laboratory of Modern Acoustics (Ministry of Education) Nanjing University Nanjing 210093 Center for Industrial and Medical Ultrasound Applied Physics Laboratory University of Washington Seattle WA 98105 USA

the dynamic behaviour of SonoVue microbubbles, a new generation ultrasound contrast agent, is investigated in real time with light scattering method. Highly diluted SonoVue microbubbles are injected into a diluted gel made of xanthan gum and water. the responses of individual SonoVue bubbles to driven ultrasound pulses are measured. Both linear and nonlinear bubble oscillations are observed and the results suggest that SonoVue microbubbles can generate strong nonlinear responses. By fitting the experimental data of individual bubble responses with Sarkar＇s model, the shell coating parameter of the bubbles and dilatational viscosity is estimated to be 7.0 nm-s-Pa.

关键词： MICROBUBBLE CONtRASt AGENtS CRItICAL-ANGLE ULtRASOUND MICROSPHERES BACKSCAttER WAtER

AdS/QCD and Applications of Light-front Holography

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Communications in theoretical Physics 2012年第4期57卷 641-664页

作者： Stanley J.Brodsky Guy f.de téramond CAO Pu-Guang SLAC National Accelerator Laboratory Stanford University Stanford CA 94309 USA and CPa-Origins Southern Denmark University Odense Denmark Massey University Palmerston North New Zealand Universidad de Costa Rica San Jose Costa Rica

Light-front holography leads to a rigorous connection between hadronic amplitudes in a higher dimensional anti-de Sitter(AdS) space and frame-independent light-front wavefunctions of hadrons in(3 + 1)-dimensional physical space-time,thus providing a compelling physical interpretation of the AdS/Cft correspondence principle and AdS/QCD,a useful framework which describes the correspondence between theories in a modified AdS 5 background and confining field theories in physical *** a first semiclassical approximation,where quantum loops and quark masses are not included,this approach leads to a single-variable light-front Schro¨dinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular *** coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate ζ which measures the separation of the constituents within a hadron at equal light-front *** internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key *** give an overview of the light-front holographic approach to strongly coupled *** particular,we study the photon-to-meson transition form factors(tffs) fMγ(Q 2) for γ→ M using light-front holographic *** results for the tffs for the η and η ' mesons are also *** novel features of QCD are discussed,including the consequences of confinement for quark and gluon condensates.A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

关键词： gauge/gravity correspondence light-front dynamics strongly coupled QCD meson and baryon spectrum meson and nucleon form factors

Peristaltic motion of third grade fluid in curved channel

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Applied Mathematics and Mechanics(English Edition) 2014年第1期35卷 73-84页

作者： S.HINA M.MUStAfA t.HAYAt f.E.ALSAADI Department of Mathematical Sciences Fatima Jinnah Women University School of Natural Sciences (SNS) National University of Sciences and Technology (NUST) Department of Mathematics Quaid-i-Azam University Department of Electrical and Computer Engineering Faculty of Engineering

＂ Analysis is performed to study the slip effects on the peristaltic flow of non-Newtonian fluid in a curved channel with wall properties. the resulting nonlinear partial differential equations are transformed to a single ordinary differential equation in a stream function by using the assumptions of long wavelength and low Reynolds number. this differential equation is solved numerically by employing the built-in routine for solving nonlinear boundary value problems （BVPs） through the software Mathematica. In addition, the analytic solutions for small Deborah number are computed with a regular perturbation technique. It is noticed that the symmetry of bolus is destroyed in a curved channel. An intensification in the slip effect results in a larger magnitude of axial velocity. further, the size and circulation of the trapped boluses increase with an increase in the slip parameter. Different from the case of planar channel, the axial velocity profiles are tilted towards the lower part of the channel. A comparative study between analytic and numerical solutions shows excellent agreement.

关键词： third grade fluid slip condition peristalsis curved channel mathematicalmodeling

A Unified Dimensionless Parameter for finite Element Mesh for Beams Resting on Elastic foundation

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Computer Modeling in Engineering & Sciences 2020年第3期122卷 955-969页

作者： Ping Lou Xinlei Zhang f.t.K.Au Zixian Zhang Yi Huang School of Civil Engineering Central South UniversityChangshaChina. Key Laboratory of Heavy Railway Engineering Structure of Education Ministry Central South UniversityChangshaChina. Department of Civil Engineering University of Hong KongHong KongChina.

Discretising a structure into elements is a key step in finite element(fE)*** discretised geometry used to formulate an fE model can greatly affect accuracy and *** paper presents a unified dimensionless parameter to generate a mesh of cubic fEs for the analysis of very long beams resting on an elastic foundation.A uniform beam resting on elastic foundation with various values of flexural stiffness and elastic supporting coefficients subject to static load and moving load is used to illustrate the application of the proposed *** numerical results show that(a)Even if the values of the flexural stiffness of the beam and elastic supporting coefficient of the elastic foundation are different,the same proposed parameter“s”can ensure the same accuracy of the fE solution,but the accuracy may differ for use of the same element length;(b)the proposed dimensionless parameter“s”can indeed be used as a unified index to generate the mesh for a beam resting on elastic foundation,whereas the use of the same element length as a criterion may be misleading;(c)the errors between the fE and analytical solutions for the maximum vertical displacement,shear force and bending moment of the beam increase with the dimensionless parameter“s”;and(d)for the given allowable errors for the vertical displacement,shear force and bending moment of the beam under static load and moving load,the corresponding values of the proposed parameter are provided to guide the mesh generation.

关键词： Beam cubic finite element elastic foundation finite element mesh unified dimensionless parameter.