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2005 Vol. 35, No. 2

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THE DEVELOPMENT OF AERO-ASTRONAUTIC TECHNOLOGY AND MODERN AERODYNAMICS
2005, 35(2): 145-152. doi: 10.6052/1000-0992-2005-2-J2005-031
Abstract(1203) PDF(1155)
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NONLINEAR DYNAMICS OF ULTRASONIC MOTORS: A SURVEY
2005, 35(2): 153-160. doi: 10.6052/1000-0992-2005-2-J2004-141
Abstract(2040) PDF(811)
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Ultrasonic motor (USM) is a stronglynonlinear system with mechanical-electric coupling and closed-loop controls,especially in case of a powerful input. Four types of nonlinearities existin such as a system. (1) nonlinearity due to the stator-rotorcontact; (2) the material nonlinearity of the stator; (3) slow-changingfactors due to temperature and wearing; (4) nonlinearity in the drivingcircuit. These nonlinear factors are related with various nonlinear phenomena, such asjump, hysteresis, drift of resonance frequency, dead zone and saturation.Furthermore, they lead to difficulties in the modeling of USM systems.Asclosed-loop controls of USM require valid dynamic models, thestudy of the modeling of USM systems becomes an important area in theresearch of USM. In this paper, common nonlinear factors in USM systems andtheir modeling methods are reviewed; published studies in the field ofnonlinear dynamics in USM systems are summarized. At the end of the paper,some trends on nonlinear dynamics of ultrasonic motor are discussed.
Jun Hu
2005, 35(2): 161-169. doi: 10.6052/1000-0992-2005-2-J2004-109
Abstract(1902) PDF(625)
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Spatial-temporal evolution of a thin film falling along aninclined plane is always a hot issue in the study of hydrodynamics. Thispaper reviews the development of falling films from the long-waveapproximation equation to the integral boundary layer equation, from thelinear instability analysis to the weakly nonlinear analysis, from the primaryinstability to the secondary instability and from the finite amplitudecomputation to the direct numerical simulation. The maintheoretical and experimental results of falling films are summarized. Recent progresses onthe heated falling film are also introduced, together with other typesof falling films.
PROGRESS IN MODEL UPDATING FOR STRUCTURAL DYNAMICS
2005, 35(2): 170-180. doi: 10.6052/1000-0992-2005-2-J2003-124
Abstract(2094) PDF(1612)
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This paper gives a brief introduction of the generalprinciple of model updating as well as the methods of model reduction andmodal expansion closely related to model updating. Some representativereferences are singled out and introduced with particular attentionto three kinds of primary methods of modelupdating, namely, direct method and parametric method, which are known astraditional methods, and updating method with neural networks. Emphases areput on their merits in application and corresponding disadvantages.Finally, some recent unresolved problemsare discussed.
OVERVIEW OF FINITE DEFORMATION SINGLE DIRECTOR SHELL MODELS WITHOUT COMPLEX GEOMETRIC CONCEPTS
2005, 35(2): 181-194. doi: 10.6052/1000-0992-2005-2-J2003-116
Abstract(2051) PDF(679)
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Based on Simo and Fox's well-known work, this article gives a comprehensiveoverview of the single director shell model and its modern representation.It describes the mathematical foundation and the mechanicalanalysis of a fully nonlinear, geometrically exact shell theory. Thisformulation of the shell equations has the advantage that, although theexact nonlinear geometric structures of the idealized two-dimensional bodyare maintained, the complex differential geometry concepts such as covariantderivatives, Riemannian connections or Christoffel symbols are avoided.Furthermore, a weak or variational statement of the local balance equationsis developed, as is ideally suited for numerical solution techniques.
ADVANCE IN DIGITAL SPECKLE CORRELATION METHOD AND ITS APPLICATION
2005, 35(2): 195-203. doi: 10.6052/1000-0992-2005-2-J2004-066
Abstract(2377) PDF(2207)
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As a non-contact optical measurement method in solid mechanics, thedigital speckle correlation method (DSCM), or alternatively, digital imagecorrelation method (DICM), has become an accepted method for measuring the surfacedisplacements field and displacement gradients in materials owing to its outstandingfeatures. The validity of the method has been shown by many instances in the lasttwenty years. Research to date on the DSCM hasled to improvements in the theory, experimental techniquesand application practices. The theory is becoming increasinglysophisticated. Some modern mathematical theories and methods (such as wavelet transformtheory, genetic algorithms and artificial neural networks, etc) are being introducedinto the DSCM. The convergencespeed and the precision of the method is further improved. The application fieldsof the method are extending from general materialsto some novel materials, from macro-field to meso-field and even micro-field, fromgeneral to severe environmental conditions and from laboratoryconditions to engineering sites, etc. In this review article, the state-of-the-artof the technique is reviewed and illustrated by referenceto recent publications on the developments and applications of DSCM.Especially, the applications of the method in micro-scale measurementsand testing of mechanicalproperties of new materials are discussed in detail. Some conclusions andpotential developing fields of the method are given in the end.
Mathematical Analyses on Global Transport In Turbulent Flow and Heat Transfer
Qi Wei
2005, 35(2): 204-210. doi: 10.6052/1000-0992-2005-2-J2004-016
Abstract(1667) PDF(698)
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Turbulence is a flow phenomenon existing widely in nature. Therelation between global transport properties and the external driving forcesis the focus of interest for various turbulent flows and heat transfer. Thevariational approach formulated by Doering and Constantin, which yieldsexplicit bounds on global transport in turbulent flow and heat transferdirectly from Navier-Stokes equations, is reviewed in this paper. Theemphasis is on the mathematical analyses of explicit bounds on globaltransport in turbulent shear flow, channel flow and Rayleigh-Benardconvection. Finally, the existing problems and the research prospects inthis field are discussed.
NUMERICAL AND EXPERIMENTAL PROGRESSES OF THE RESEARCH ON THE JETS IN CROSSFLOW
2005, 35(2): 211-220. doi: 10.6052/1000-0992-2005-2-J2004-004
Abstract(1744) PDF(907)
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A turbulent jet turning transversely into a uniformcrossflow is an important type of fluid flow with applications invarious engineering fields, e.g. internal film cooling of turbine blades,dilute air jets in combustion chambers, jet from V/STOL aircraft intransition flight, and waste disposal from smoke stacks into the atmosphere.The jet in a crossflow is a highly complex turbulent flow due to the actionof many structures in the field, including the jet shear-layervortices, the system of horseshoe vortices, the counter-rotating vortexpair, and the wake vortices. These phenomena have been observed in number ofprevious investigations in theoretical, experimental and numerical studies,and some structural features and flowing mechanisms have been revealed. Inthis paper, from the aspects of the numerical simulation and theexperimental research, the present research methods and results areanalyzed, and the forecasting ability of both the different turbulencemodels and various measuring ways are summarized. In the end, someunsettled issues are discussed and the developing directions in this fieldare also pointed out.
ADVANCES IN SYNTHETIC JET TECHNOLOGY AND APPLICATIONS IN FLOW CONTROL
2005, 35(2): 221-234. doi: 10.6052/1000-0992-2005-2-J2004-044
Abstract(3553) PDF(1494)
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Flow control is one of important areas of research in fluid technology,and in the 21st century, the most important breakthrough in aerodynamicsmay be in the area of flow control. The synthetic jet, a zero mass flux jetbased on vortex dynamics, has been a remarkable and promising activeflow control technology in the recent decade. First, the synthetic jetactuators and the main types of actuators are introduced briefly in thispaper. The developments of actuators are summarized: thehigh-frequency, high-power, robust synthetic jet actuators and themini-actuators. Secondly, the operation principle of a synthetic jetactuator, the formation of a synthetic jet, the unique characteristics ofthe synthetic jet flow-field and the characteristics of the synthetic jettechnology are summarized. Lastly, the main and potential applications ofthe synthetic jet for flow control, such as flow separation control,aerodynamic control, jet vectoring control, mixing augmentation, heater and masstransfer enhancement, flow-induced noise suppression, micro-fluidic flowcontrol, flight control, particle scattering and synthetic jetgyroscope, areintroduced, and the main controlling mechanisms for these applications arealso discussed.
RESEARCH ADVANCES IN THE STUDY OF CONSTITUTIVE MODELS FOR SEA ICE DYNAMICS
2005, 35(2): 235-248. doi: 10.6052/1000-0992-2005-2-J2003-024
Abstract(2103) PDF(777)
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A series of constitutive models have been established for seaice dynamics under different temporal-spatial scales from the 1970s. Inthis paper, the existing constitutive models were divided into fourgroups, that is, elastic-plastic model, viscous-plastic model and its modifications,anisotropic model and viscous-elastic-plastic model of granular flowdynamics. Their characteristics and applications in the sea ice dynamicswere discussed. Especially, the viscous-plastic model and its modifications,which were applied widely at large and meso-scales in the polar andsub-polar ice field, were discussed in details. At the end, the keyissues inconstitutive model for sea ice dynamics were discussed. Theviscoelasic-plastic model should be developed to improve the precision ofsea ice simulation at large and meso-scales. The granular flow dynamics withviscous-elastic-plastic model, which was used at small scale satisfactorily,can be applied widely at large and meso-scales when its computationalefficiency is improved. With the aids of indoor physical experiments, thescale law should be investigated further to establish the relationship in thesea ice constitutive model at different scales.
ADVANCE OF WELL TEST ANALYSIS FOR HETEROGENOUS RESERVOIRS
2005, 35(2): 249-259. doi: 10.6052/1000-0992-2005-2-J2003-049
Abstract(1756) PDF(948)
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Based on the definition of the reservoir types used in the welltest analysis, this review forcuses onfour points: theformation heterogeneity, the fluid distribution, the mathematical model andthe test data interpretation method. The concepts, such as the partiallyregular heterogeneous reservoir and arbitrarily heterogeneous reservoir, areexpatiated in this paper. The present state and future trend of research arepointed out. It is best to combine the geological data and the dynamicdata of the reservoir development to interpret the well test data. Numericalwell test analysis method is the new trend for the future test analysis.
NONLINEAR EDDY VISCOSITY AND ALGEBRAIC STRESS MODELS FOR SOLVING COMPLEX TURBULENT FLOWS
2005, 35(2): 260-282. doi: 10.6052/1000-0992-2005-2-J2004-107
Abstract(2123) PDF(773)
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Nonlinear eddy viscosity and algebraic stress models are currently providingan invaluable link between the more common linear eddy viscosity turbulencemodels and the full differential Reynolds stress forms. With the increasedpopularity has come an abundance of different formulations. The purpose ofthis review is to provide a cohesive framework for the variety of modelsproposed and to highlight the various similarities and differences among themodels. Their link with differential Reynolds stress models and theirimproved predictive capability over linear eddy-viscosity models is alsohighlighted.
2005, 35(2): 283-284. doi: 10.6052/1000-0992-2005-2-J2004-175
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2005, 35(2): 285-285. doi: 10.6052/1000-0992-2005-2-J2005-058
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2005, 35(2): 286-287. doi: 10.6052/1000-0992-2005-2-J2005-049
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2005, 35(2): 288-298. doi: 10.6052/1000-0992-2005-2-J2005-051
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2005, 35(2): 299-299. doi: 10.6052/1000-0992-2005-2-J2005-050
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2005, 35(2): 300-300. doi: 10.6052/1000-0992-2005-2-J2004-182
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2005, 35(2): 301-301. doi: 10.6052/1000-0992-2005-2-J2004-181
Abstract(1047) PDF(612)
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Retrospectives,Review Articles and Special Issues Applied Mechanics Reviews,Volume 57(2004)
2005, 35(2): 303-303. doi: 10.6052/1000-0992-2005-2-J2005-108
Abstract(1046) PDF(528)
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Annual Review of Fluid Mechanics, Volume 37,2005
2005, 35(2): 304-304. doi: 10.6052/1000-0992-2005-2-J2005-109
Abstract(1427) PDF(541)
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