力学进展 - 开云棋牌官方

2012, 42(3): 229-230. doi: 10.6052/1000-0992-2012-3-20120301

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ADVANCES AND OUTLOOK IN TURBULENT RAYLEIGH-BÉNARD CONVECTION

ZHOU Quan, XIA Keqing

2012, 42(3): 231-251. doi: 10.6052/1000-0992/11-163

Abstract(2404)

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Turbulent Rayleigh-B閚ard (RB) convection, a fluid layer heated from below and cooled from above, has become a paradigm for the study of general convection phenomena that occurs ubiquitously in nature and in many engineering applications. This paper presents an overview of recent advances in the following major areas of RB convection: turbulent heat transport, thermal plumess, large-scale circulation, and small-scale properties of velocity and temperature fields. A brief description of recent developments in the studies using non-traditional RB configurations is also presented. We end by pointing out main remaining issues and challenges and giving an outlook on the future development.

REVIEW ON THE INSTABILITY STRUCTURE IN COMPRESSIBLE BOUNDARY LAYERS AND MIXING LAYERS AND ITS APPLICATION

SHEN Qing, YUAN Xiangjiang, WANG Qiang, YANG Wubing, GUAN Faming, JI Feng

2012, 42(3): 252-261. doi: 10.6052/1000-0992/11-045

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This paper reviews the studies on instability structures in compressible boundary layer and mixing layers and their applications. These include the instability in hypersonic plane boundary layers, the mechanism of the effect of angle of attack on the hypersonic boundary layer transition on sharp cone and the instability in compressible mixing layers. All of these results are helpful for people to understand the transition process and turbulent coherent structure in high speed flows.

THE INSTABILITY AND CONTROL OF COMPRESSIBLE CROSS FLOWS

XU Guoliang, FU Song

2012, 42(3): 262-273. doi: 10.6052/1000-0992/11-059

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Boundary layer transition prediction and control is one of the most ambitions topics of research activities in aerodynamics. The crossflow instability of a three-dimensional boundary layer is a main factor affecting the laminar transition. The current understanding of 3-d boundary-layer transition is reviewed. Recent advances in receptivity, primary instability, secondary instability and transition control of crossflow boundary layer flows are discussed. Challenges about compressible crossflow transition remain and prospects are presented as well.

NUMERICAL SIMULATION OF SHOCK WAVE/TURBULENCE INTERACTIONS

WANG Guolei, LU Xiyun

2012, 42(3): 274-281. doi: 10.6052/1000-0992-11-057

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We provide an overview of recent progresses in numerical simulations of the shock wave/turbulence interactions, including the interactions of shock wave with homogeneous and isotropic turbulence, turbulent boundary layers, turbulent jets and wakes. The characteristics of the interaction depend on a variety of factors, such as the strength, location and shape of the shock wave, the boundary conditions, as well as the state of turbulence and the compressibility of the incoming ow. The interaction substantially results in considerable changes in the ow structures, the features of shock wave and the turbulent statistical properties. Finally, we discuss some issues in the numerical simulation of shock wave/turbulence interactions.

PROGRESS IN THE BIONIC STUDY ON GECKO'S MICRO-ADHESION MECHANISM

CHEN Shaohua, PENG Zhilong

2012, 42(3): 282-293. doi: 10.6052/1000-0992/11-138

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A class of animals possesses special climbing abilities in nature, which attracts enormous academic interests. To investigate the macro- and micro-mechanisms of such animals’ adhesion can not only develop relevant surface/interface mechanics, but also provide novel ideas for the design of advanced adhesive materials and appropriate adhesive system for a micro-climbing robot, and shed lights on solving methods for adhesive failure problems in MEMS/NEMS and AFM. Experiments have found that the adhesive system on gecko’s foot is hierarchical, which will produce strong adhesion. There are millions of setae on a gecko’s foot and each seta will branch into hundreds of spatulae. The spatula is the smallest adhesive structure in a gecko’s foot, which is about 200nm in width and length, about 5nm in thickness. The adhesive behavior of a spatula on a surface looks like that of a finite-sized nano-film. The basic principle of the adhesion is due to Van Der Waals force between two surfaces. Plenty of spatulae will cause the adhesion force large enough to support the weight of a gecko. In the present paper, considering the real shape of the smallest adhesive structure, which is similar to a nano-film with a finite length, we present an overview of the main influence factors of the micro-adhesion mechanism of gecko’s spatula, including the effects of adhesion length, thickness and peeling angles of a finite nano-film on the adhesion force, the effects of surface roughness and environmental humidity on surface/interface adhesion. Experimental investigations as well as theoretical and numerical studies are also reviewed. Finally, possible challenges and future development of the biomimetic adhesive mechanics are proposed and prospected.

Recent progresses in hematological dynamics

LEI Jinzhi

2012, 42(3): 294-313. doi: 10.6052/1000-0992/11-148

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Hematopoiesis is a complex regulation system in human body, which is a typical nonlinear delay dynamical system, including proliferation, maturation and apoptosis of different types of blood cells, and feedback controls to these processes. Deregulations in the hematopoiesis can induce many dynamical blood diseases. Studies of hematological dynamics are important for understanding and treating these diseases. This paper surveys recent progresses in hematological dynamics studies, including basic knowledge of the hematopoiesis, clinical manifestation of dynamical blood disease and their dynamical characteristics, theoretical models and dynamical analysis.

A REVIEW ON MECHANICS PROBLEMS IN MICRONEEDLE DESIGN AND PENETRATING PROCESS

MA Guojun, WU Chengwei

2012, 42(3): 314-331. doi: 10.6052/1000-0992/11-155

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Recently, a novel technology known as microneedles have received much attention because they can be used for transdermal drug delivery and blood sampling in a painless and minimally invasive manner. However, there are still some problems that restrict its practical applications in clinical therapies. In this review, we first give a presentation of this novel technology, including its development history and development trends, and then discuss the existing mechanics problems. First, researches on the mechanics problems of microneedle are elaborated, including insertion force, structure strength, stiffness and drug deliver via microneedle. And then, we present new developments in the study on biomicroneedles and bionicmicroneedles, and describe the micronanostructures and mechanics principle of the biomicroneedle using a super small penetrating force, and finally discuss the inspirations provided by the biomicroneedle for the improvement of artificial microneedles design.

MECHANOSENSITIVE CHANNELS: INSIGHTS FROM MOLECULAR MODELING AND SIMULATIONS

XIE Junyu, DING Guanghong

2012, 42(3): 332-346. doi: 10.6052/1000-0992-11-129

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Mechanosensitive channels play an important role in various physiological processes. The research on Mechanosensitive channels has been conducted more than two decades by now. In the experimental aspect, the determination of crystal structures of mechanosensitive channels of large and small conductance makes it possible to develop molecular modeling and simulation investigations on MS channels, which gives us a significantly deeper insight into mechanism of mechanosensitive channels. During theoretical studies on ion channels, different simulation methods and calculation skills display their superiorities as well as specific performances, which offer us different viewpoints to analyze membrane channels; however, they also have their own limitations. Particularly, among many ion channel analysis technologies, molecular dynamic simulation plays an outstanding role. The emergence of molecular dynamic simulation presents a more comprehensive and detailed description of the structural and functional relationship and dynamic mechanism of MS channels, which we can not achieve via many other technologies. On the other hand, molecular dynamic simulation consists of several methods, and different methods offer us different paths to study MS channels. That’s why in this review, we focus on the computational aspect of mechanosensitive channels analysis, with particular emphasis laid on molecular dynamic simulations. In the context of molecular dynamic simulation, we discuss the dynamic mechanism of MS channels, including structure, lipid environment, mechanical stimulation, voltage dependence and gating configuration. Meanwhile comparisons of the advantages and disadvantages of different simulation technologies will provide us better tools of research in the future. Finally, we also sum up the domestic breakthrough and great achievements in ion channels research, and all of these will definitely provide us new thoughts and inspirations to study MS channels.

MECHANICAL BEHAVIOR OF PURE HYDRATES

YU Yibing, NING Fulong, JIANG Guosheng, ZHANG Ling

2012, 42(3): 347-358. doi: 10.6052/1000-0992/11-136

Abstract(1431)

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Mechanical behavior of pure hydrates are foundation of the research on mechanical properties of hydrate-bearing sediments, and are thus closely connected with production of gas hydrates, geological hazards, CO₂ storage, gas storage and transportation and many other aspects. However, limited by the conditions of hydrate formation and the defects of hydrate samples, there are still some disputes and gaps in the current study of mechanical properties of pure hydrates. In this paper, we summarized and analyzed the state-of-art of mechanical behavior of pure hydrates from experimental measurements and theoretical calculations, respectively. It is suggested that the combination of improved macroscopic experiments and microscopic molecular simulations is a good way to eliminate the influence of the defects of hydrate samples and reveal the origins and essences of similarities and differences between pure hydrates and ices, to understand the effects of microporosity, residual water and gas in the hydrate samples and to bridge the microscopic characteristics and the macroscopic mechanical behavior for pure hydrates.

THE INTRODUCTION OF APPLICATION PROJECTS ON MECHANICS IN 2012

ZHANG Panfeng, ZHAN Shige, LV Shouqin, ZHANG Wenming

2012, 42(3): 359-360. doi: 10.6052/1000-0992-2012-3-20120311

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INTRODUCTION TO THE ADVANCED COURSE ON MECHANICS OF SOFT MATTER

CHEN Weiqiu, QU Shaoxing, QIAN Jin, ZHAN Shige, MENG Qingguo

2012, 42(3): 361-364. doi: 10.6052/1000-0992-2012-3-20120312

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