bluuebunny/crossref_metadata_2025 huggingface dataset:
Extended Models for Transitional Rough Wall Boundary Layers With Heat Transfer—Part II: Model Validation and Benchmarking
Authors: Stripf M. , Schulz A. , Bauer H.-J. , Wittig S.
Published: April 2009

Two extended models for the calculation of rough wall transitional boundary layers with heat transfer are presented. Both models comprise a new transition onset correlation, which accounts for the effects of roughness height and density, turbulence intensity, and wall curvature. In the transition region, an intermittency equation suitable for rough wall boundary layers is used to blend between the laminar and fully turbulent states. Finally, two different submodels for the fully turbulent boundary layer complete the two models. In the first model, termed KS-TLK-T in this paper, a sand roughness approach from (Durbin, et al., 2001, “Rough Wall Modification of Two-Layer k-ε ,” ASME J. Fluids Eng., 123, pp. 16–21), which builds on a two-layer k-ε-turbulence model, is used for this purpose. The second model, the so-called DEM-TLV-T model, makes use of the discrete-element roughness approach, which was recently combined with a two-layer k-ε-turbulence model by the present authors. The discrete-element model will be formulated in a new way suitable for randomly rough topographies. Part I of this paper will provide detailed model formulations as well as a description of the database used for developing the new transition onset correlation. Part II contains a comprehensive validation of the two models, using a variety of test cases with transitional and fully turbulent boundary layers. The validation focuses on heat transfer calculations on both the suction and the pressure side of modern turbine airfoils. Test cases include extensive experimental investigations on a high pressure turbine vane with varying surface roughness and turbulence intensity, recently published by the current authors, as well as new experimental data from a low pressure turbine vane. In the majority of cases, the predictions from both models are in good agreement with the experimental data.
On the Coupling of Designer Experience and Modularity in the Aerothermal Design of Turbomachinery
Authors: Jarrett Jerome P. , Ghisu Tiziano , Parks Geoffrey T.
Published: April 2009

The turbomachinery aerodynamic design process is characterized both by its complexity and the reliance on designer experience for success. Complexity has led to the design being decomposed into modules; the specification of their interfaces is a key outcome of preliminary design and locks-in much of the final performance of the machine. Yet preliminary design is often heavily influenced by previous experience. While modularity makes the design tractable, it complicates the appropriate specification of the module interfaces to maximize whole-system performance: coupling of modularity and designer experience may reduce performance. This paper sets out to examine how such a deficit might occur and to quantify its cost in terms of efficiency. Two disincentives for challenging decomposition decisions are discussed. The first is where tried-and-tested engineering “rules of thumb” accord between modules: the rational engineer will find alluring a situation where each module can be specified in a way that maximizes its efficiency in isolation. The second is where there is discontinuity in modeling fidelity, and hence difficulty in accurately assessing performance exchange rates between modules. In order to both quantify and reduce the potential cost of this coupling, we have recast the design problem in such a way that what were previously module interface constraints become key system design variables. An example application of our method to the design of a generic turbofan core compression system is introduced. It is shown that nearly one percentage point of the equivalent compressor adiabatic efficiency can be saved.
Symmetric Galerkin Boundary Element Methods
Authors: Bonnet Marc , Maier Giulio , Polizzotto Castrenze
Published: April 2009

This review article concerns a methodology for solving numerically, for engineering purposes, boundary and initial-boundary value problems by a peculiar approach characterized by the following features: the continuous formulation is centered on integral equations based on the combined use of single-layer and double-layer sources, so that the integral operator turns out to be symmetric with respect to a suitable bilinear form. The discretization is performed either on a variational basis or by a Galerkin weighted residual procedure, the interpolation and weight functions being chosen so that the variables in the approximate formulation are generalized variables in Prager’s sense. As main consequences of the above provisions, symmetry is exhibited by matrices with a key role in the algebraized versions; some quadratic forms have a clear energy meaning; variational properties characterize the solutions and other results, invalid in traditional boundary element methods enrich the theory underlying the computational applications. The present survey outlines recent theoretical and computational developments of the title methodology with particular reference to linear elasticity, elastoplasticity, fracture mechanics, time-dependent problems, variational approaches, singular integrals, approximation issues, sensitivity analysis, coupling of boundary and finite elements, and computer implementations. Areas and aspects which at present require further research are identified, and comparative assessments are attempted with respect to traditional boundary integral-elements. This article includes 176 references.
Hyperbolic Thermoelasticity: A Review of Recent Literature
Authors: Chandrasekharaiah D. S.
Published: April 2009

This review article is a continuation of a previous article by the author, Thermoelasticity with second sound: A review, which appeared in this journal in March, 1986 (Appl Mech Rev39(3) 355-376). Here, attention is focused on papers published during the past 10-12 years. Contributions to the theory of thermoelasticity with thermal relaxation and the temperature-rate dependent thermoelasticity theory are reviewed. The recently developed theory of thermoelasticity without energy dissipation is described, and its characteristic features highlighted. A glance is made at the new thermoelasticity theory which includes the so-called dual-phase-lag effects. There are 338 references.
Influence of Turbulent Mechanical Stresses on Microorganisms
Authors: Bałdyga J. , Pohorecki R.
Published: April 2009

Many phenomena depend on the features of the fine-scale structure of turbulence, including its intermittency. This article discusses the problem of the turbulent “shear” in biotechnology including the effect of the shear stress on particles (cells, flocs, cells immobilized on microcarriers). Traditionally, the effect of intermittency has not been taken into account in the shear problem and the theory of isotropic turbulence introduced by Kolmogorov (1941) based on average values of the rate of kinetic energy dissipation, velocity fluctuactions, rates of strain, turbulent stresses etc. has been applied. In this paper a multifractal formalism is employed to describe intermittency; the results of multifractal approach are then compared with predictions of other models of intermittent and non-intermittent turbulence. The multifractal model of intermittent turbulence has been used to derive equations describing flow-particle interactions, including: equations describing turbulent stresses acting upon particles in the inertial and viscous subranges of turbulence; mass transfer to small particles suspended in turbulent fluid; turbulent rupture of flocs; particles encounters in turbulent flow including the average number of collisions per unit time in the inertial and viscous subranges of turbulence and the severity of collisions; mechanical stress generated by bubble coalescence. Generally, the article shows how the traditional approach to the shear problem in turbulence, based on the Kolmogorov theory, can be extended by including the influence of intermittency. This review article includes 47 references.
Pneumatically Agitated Bioreactors in Industrial and Environmental Bioprocessing: Hydrodynamics, Hydraulics, and Transport Phenomena
Authors: Chisti Yusuf
Published: April 2009

Major aspects of design and operation of pneumatically agitated bioreactors are reviewed. The focus is on considerations that are relevant to industrial practice. Airlift bioreactors are emphasized. The treatment covers hydraulics, hydrodynamics, gas-liquid and solid-liquid mass transfer, heat transfer, mixing, and suspension. Newtonian and non-Newtonian systems are discussed. Applications in microbial fermentations, animal and plant cell culture, biotransformations with immobilized enzymes, and treatment of wastewater are outlined. Comparisons with more conventional bioreactor technologies are made. Design features for sterile processing in airlift systems are detailed. The evidence for superior performance of airlift bioreactors is overwhelming. Excellent productivities have been demonstrated with yeasts, bacteria, and filamentous fungi. Processes that produce highly viscous broths, including several biopolymer producing fermentations, have been proven in airlift devices. Similarly, many hybridoma cultures and plant cell suspensions have given good results. As a general rule, volumetric productivity of airlift bioreactors equals or betters that of conventional stirred tanks. Typically, this level of performance is achieved at substantially lower power input than in stirred vessels. Furthermore, the probability of mechanical failure and likelihood of loss of sterility are lower with airlift bioreactors. In wastewater treatment, too, airlift devices have far outperformed conventional systems. Airlift bioreactors accept higher BOD loadings, produce less sludge, and the degradation rate is faster; performance improves with increasing scale of operation. This review article includes 328 references.
Hydrodynamics of Stirred Bioreactors
Authors: Nienow A. W.
Published: April 2009

This review of the hydrodynamics of stirred bioreactors begins with an introduction to the agitation problems of particular concern in such systems. This is followed by a brief review of some basic concepts in turbulence and rheology of relevance to bioreactors. Important aspects of single phase mixing in low viscosity, high viscosity and Theologically complex broths are then covered in some detail including flow patterns, power number versus Reynolds number plots (including the modification of the latter to allow for shear thinning broths), flow numbers, energy dissipation rates and flow close to impellers and between multiple impeller systems. From these basic principles, the problem of homogenization is then covered in depth because of its significance for bioreactor performance. Aeration concepts are then introduced and the behavior of traditional Rushton turbine impellers is then treated in detail, covering the flow patterns, aerated power characteristics, mixing time and scale-up considerations. The weaknesses of the Rushton turbine are then discussed which leads into a section describing how more modern impellers are able to improve on many of these, especially emphasising their ability to introduce more energy dissipation into the broth and handle more air before flooding, both of which enhance oxygen transfer. The improvement in bulk blending found with multiple axial flow agitators is brought out too. Finally, the retrofitting of fermenters originally containing Rushton turbines with these more modern impellers is discussed. In conclusion, it is clear that there have been substantial increases in the understanding of stirred bioreactor hydrodynamics. However, whilst further understanding will occur within the framework discussed here, the expectation must be that computational fluid dynamics will increase in importance in spite of the difficulty of handling complex rheology, multiphase systems and biological responses. This review article has 135 references.
Neural Computing in Mechanics
Authors: Zeng Pan
Published: April 2009

Recently, the artificial neural network has experienced a surge in popularity and is now one of the most rapidly expanding areas of research across many disciplines. The main reason is in its powerful and adaptive abilities to treat various complex problems. One can be sure that with its further developments, neural networks will strongly impact many conventional disciplines from the standpoint of methodology. In the field of mechanics, the research and application of both neural network and revolutionary computing are especially active and successful. The back propagated multilayered network is one of the main types applied to engineering. The related works concern almost all topics of engineering science and mechanics, such as, approximation of structural analysis, assessment of structural damage, fault diagnosis, prediction, strategic management, decision making, structural optimization, etc. The aim of this review is to summarize and recapitulate the up-to-date developments and applications of neural networks and computing in mechanics, with emphasis on the back propagation algorithm of multilayer networks. Not only are the fundamental principles outlined clearly, but some typical examples are also presented. It is hoped that this review article can promote the development and applications of neural network and computing in mechanics. This article contains 221 references.
Monte Carlo Treatment of Random Fields: A Broad Perspective
Authors: Spanos P. D. , Zeldin B. A.
Published: April 2009

A review of a number of methods for random fields simulation in conjunction with Monte Carlo studies of probabilistic mechanics problems is presented from a broad perspective. This article complements some of the previous review articles in that it compares various simulation algorithms, assesses their relative computational efficiency and versatility, discusses the properties of generated field samples, and incorporates some of the recent developments. Collectively, a comprehensive discussion of the covariance decomposition method, the spectral method, the ARMA method, the noise shower method, the scale refinement methods, and the turning band method is attempted. For tutorial effectiveness univariate, uni-dimensional, Gaussian, and homogeneous fields are discussed, primarily in connection with various simulation methods. Nevertheless, appropriate references are included addressing the simulation of more general fields. This review article contains 110 references.
Advances in the Fundamental Aspects of Turbulence: Energy Transfer, Interacting Scales, and Self-Preservation in Isotropic Decay
Authors: Zhou Ye , Speziale Charles G.
Published: April 2009

The fundamental aspects of isotropic turbulence are reviewed in order to gain a better insight into the physical processes of turbulence. After first reviewing the Kolmogorov energy spectrum and the energy cascade, the Kolmogorov hypothesis of local isotropy is discussed in depth. Then, the detailed physical processes involving energy transfer and interacting scales in isotropic turbulence, including triad interactions, are reviewed. The inertial range and self-similarity are also discussed along with the response of the small scales to large-scale anisotropy and the final stages of the decay process. Results from direct and large-eddy simulations of isotropic turbulence—including a discussion of subgrid scale modeling—are then discussed in detail to illustrate these points. The article closes with a review of self-preservation in isotropic turbulence and a discussion of the prospects for future research. It contains 155 references.
Finite Element Analysis of Hyperelastic Components
Authors: Nicholson D. W. , Nelson N. W. , Lin B. , Farinella A.
Published: April 2009

Finite element analysis of hyperelastic components poses severe obstacles owing to features such as large deformation and near-incompressibility. In recent years, outstanding issues have, to a considerable extent, been addressed in the form of the hyperelastic element available in commercial finite element codes. The current review article, which updates and expands a 1990 article in Rubber Reviews, is intended to serve as a brief exposition and selective survey of the recent literature. Published simulations are listed. Rubber constitutive models and the measurement of their parameters are addressed. The underlying incremental variational formulation is sketched for thermomechanical response of compressible, incompressible and near-incompressible elastomers. Coupled thermomechanical effects and broad classes of boundary conditions, such as variable contact, are encompassed. Attention is given to advanced numerical techniques such as arc length methods. Remaining needs are assessed. This review article contains 142 references.
Contact Problems for Elastic Bodies With Initial Stresses: Focus on Ukrainian Research
Authors: Guz’ A. N. , Babich S. Yu. , Rudnitsky V. B.
Published: April 2009

In the present review article general results concerning problems of contact interaction (contact problems) of pre-stressed bodies with rigid, and elastic punches (facings) are presented. The modern classification of investigations on contact problems for bodies with initial stresses is based on two approaches. The first approach is applicable to bodies with a specific type of elastic potential. The second approach is developed in parallel with the first one. It describes investigations on contact problems for pre-stressed bodies with an arbitrary structure of an elastic potential in a general form for compressible and incompressible materials. In the last case, investigations were carried out in a common form for the theory of large (finite) initial strains and various variants of the theory of small initial strains. The formulation of the problems is given, and methods of solving planar and spatial contact problems for bodies with initial stresses are developed. Procedures of the theory of complex variables and methods of Riemann-Hilbert are used. For planar problems, the authors introduce planar potentials of the linearized static and dynamic problems for elastic compressible and incompressible bodies with initial stresses. In the case of spatial contact problems, various procedures are used: general solutions of spatial static problems for elastic bodies with initial stresses, methods of harmonic potential theory, integral transformations, and integral equations using numerical methods of investigation. The essential numerical results in the form of graphs and tables are presented. These give the quantitative and qualitative analysis of the influence of initial stresses on the main characteristics of contact problems. This review contains 98 references.
Videogrammetric Methods in Velocimetry
Authors: Dracos Th. , Gruen A.
Published: April 2009

Photogrammetry has been successfully applied in surveying and mapping for a long time. New imaging techniques, digital data acquisition and storage and powerful computing facilities transformed photogrammetry into videogrammetry, a technique applied in many fields for precise and reliable position measurements. Two applications of videogrammetry in fluid mechanics are presented in this article. Both are at their present stage of development suited for three-dimensional velocity measurements in liquids. One is based on tracking particles seeded in the liquid by using three to four synchronized video-cameras (PTV). It allows one to determine accurately the velocity vectors at a large number of points inside a thick observation volume and also to follow the trajectories of these particles for sufficiently long time periods. It is especially well suited for Lagrangian measurements in flows. The other tracks small three-dimensional patterns in flows of liquids tagged by fluorescent dye (LIFV). The three-dimensional Laser Induced Fluorescence images needed are obtained by sweeping rapidly a thin laser-light sheet with simultaneous imaging using a high speed solid-state camera. The method yields the shift and deformations of the liquid volumes associated with these patterns and allows one to determine velocity vectors and their derivatives simultaneously and accurately at a large number of points inside the observation volume. This review article includes 100 references.
Methods of Isolation of Modal Resonances
Authors: Veksler Naum , Izbicki Jean-Louis , Conoir Jean-Marc , Rembert Pascal
Published: April 2009

The scattering problem by immersed targets involves the resonance phenomenon. Different methods of isolation of modal resonances are discussed: the Resonant Scattering Theory (the different backgrounds used in this method are considered), the phase gradient method (which is partly independent of the background choice), and the Argand diagram method (leading to both theoretical and experimental determination of the frequency and the width of resonances) and an exact description of the resonance components of partial modes (involving the determination of the roots of the characteristic equation in the complex frequency plane). The results provided by these methods are compared, their validity domain is discussed. Whatever the method, the resonant components appear as Breit-Wigner functions: this is the common point between the different methods. This review article includes 119 references.
A Review of Material Frame-Indifference in Mechanics
Authors: Speziale Charles G.
Published: April 2009

The Principle of Material Frame-Indifference in various areas of mechanics is critically reviewed from a basic theoretical standpoint. Modern continuum mechanics is considered along with statistical mechanics and turbulence in an effort to better understand this commonly used axiom. It is argued that Material Frame-Indifference is a restricted invariance that can be highly useful in the formulation of constitutive equations but must be applied with caution. Material Frame-Indifference applies, in a strong approximate sense, to most areas of continuum mechanics where there is a clear cut separation of scales so that the ratio of fluctuating to mean time scales is extremely small. While it breaks down for the three-dimensional case, it rigorously applies to Reynolds stress models in the limit of two-dimensional turbulence where an analogy is made between the Reynolds stress tensor and the non-Newtonian part of the stress tensor in the laminar flow of a non-Newtonian fluid. On the other hand, the general invariance group of constitutive equations that is universally valid is the extended Galilean group of transformations which includes arbitrary time-dependent translations of the spatial frame of reference; rotational frame-dependence then enters exclusively through the intrinsic spin tensor. In order to definitively address this issue it is necessary to establish what the invariance group is of solutions to the fluctuation dynamics from which constitutive equations are formally constructed. The implications of these results for future research in a variety of different fields in mechanics are thoroughly discussed. This article includes 52 references.
Real Porous Media: Local Geometry and Macroscopic Properties
Authors: Adler P. M. , Thovert J.-F.
Published: April 2009

The random geometry of real porous media is analyzed with the objective of reproducing it numerically; adequate algorithms are proposed for consolidated materials which may be statistically homogeneous or not, and may possess more than one solid phase; random packings of star-shape grains are built to mimic non-consolidated materials which are usually obtained by settling processes. The macroscopic properties of all these media can be deduced by solving the local partial differential equations which govern the phenomena; finite difference schemes are used most of the time. A number of physical situations have been already addressed. Elementary transport phenomena such as convection, diffusion and convection-diffusion provide the basic illustrations of our methodology. Multiphase flows is an exception in the sense that the resolution is achieved by means of a lattice-Boltzmann algorithm. The electrokinetic phenomena associated with the motion of an electrolyte through a charged medium are addressed close to equilibrium, in the limit of small dzeta potentials and thick double layers. Industrial processes may involve deposition and/or dissolution of a solute; first-order reactions of a single solute could be successfully analyzed and rationalized with the help of the Pe´clet and the Damko¨hler numbers. Similarly, the macroscopic mechanical properties of the solid matrix of a porous medium can be obtained by solving the elastostatic equations; macroscopic coefficients such as the equivalent Young’s modulus were derived for a number of structures. Some tentative remarks conclude this review. This article contains 289 references.
Energy Absorption Capability and Crashworthiness of Composite Material Structures: A Review
Authors: Carruthers J. J. , Kettle A. P. , Robinson A. M.
Published: April 2009

The controlled brittle failure of thermosetting fibre-reinforced polymer composites can provide a very efficient energy absorption mechanism. Consequently, the use of these materials in crashworthy vehicle designs has been the subject of considerable interest. In this respect, their more widespread application has been limited by the complexity of their collapse behavior. This article reviews the current level of understanding in this field, including the correlations between failure mode and energy absorption, the principal material, geometric, and physical parameters relevant to crashworthy design and methods for predicting the energy absorption capability of polymer composites. Areas which require further investigation are identified. This review article contains 70 references.
Drained Granular Material Under Cyclic Loading With Temperature-Induced Soil/Structure Interaction
Authors: England George L. , Tsang Chiu M. , Dunstan Treve , Wan Richard G.
Published: April 2009

This review article is divided into three parts. Firstly, three soil/structure interaction problems are described in which strain is imposed on the soil caused by solar heating of the structures. They are modeled by reference to cyclic ratcheting strains with the help of a simple two-component model comprised of one elastic element and one element of granular material. Possible stable shakedown solutions are described for a bridge and filter bed. In contrast, a tower structure may become progressively less stable with increasing load cycles. Secondly, our experimental results from plane strain biaxial tests on sand under drained cyclic loading conditions are shown to complement the work of others. Results reveal the existence, in strain control experiments, of a unique shakedown stress ratio, S, which is independent of cyclic strain amplitude, but with the associated void ratios being strain-amplitude dependent. At very small strain amplitudes S may decrease. Thirdly, numerical modeling methods are described. These include applications of nonlinear elasticity, and elasto-plasticity including endochronic theory, to predict the behavior of granular materials under cyclic loading. It is concluded that temperature-induced cyclic loadings are of importance in some soil/structure interaction situations, and that reliable predictions can be made in simple cases. Further knowledge and research is needed to fully predict the incremental evolution of fabric change during cyclic stressing and cyclic straining. Either existing models will be required to be modified, or new ones formulated to capture all the features covered in this paper. There are 51 references included with this article.
Interactions of Space Bodies With Atmospheres of Planets
Authors: Stulov V. P.
Published: April 2009

In this review article, a modern theory of meteor body motion in the atmosphere is described. The theory is based on the results of high-speed aerodynamics. The author understands that such an application is difficult and unusual. The difference between space vehicle aerodynamics and bolide physics is, first of all, in absence of knowledge about shapes of meteoroids and of their physical-mechanical properties. On the other hand, the main aerodynamical laws are the same for vehicles and meteoroids. This permits one to achieve some new developments in meteor physics. In the first section, a simple analytical model for meteor trajectories is developed. The second and fourth sections of the article contain high-speed aerodynamics results: inviscid gas flow past bodies, and convective and radiative heat transfer. The third section is devoted to one of the difficult problems in meteor physics-the theory of meteoroid destruction due to aerodynamical loading. Finally, the fifth section contains some common questions on bolide phenomema. For the solution of meteor physics problems, both analytical and numerical methods are used. As such problems contain a number of determining parameters which are not accurately known, the analytical methods are preferable. The numerical methods are necessary for calculation of complex gasdynamical structures forming during the motion of the meteor bodies in the atmosphere. There are 50 references included at the end of this article.
Localized Impact on Sandwich Structures With Laminated Facings
Authors: Abrate Serge
Published: April 2009

Currently, there is strong interest in the effects of impact induced damage to composite structures as evidenced by the large number of articles on this topic that have appeared in the literature in recent years. With laminated composite structures, foreign object impacts, that are expected to occur during the life of the structure, can introduce damage that is often difficult to detect and can significantly reduce the strength of the structure. Research efforts concentrate on monolithic laminates while sandwich structures with laminated facings, which are also used extensively in aerospace and other applications, received less attention. A comprehensive review of the literature dealing with impact on sandwich structures is presented in this review article. The mechanics of contact between a rigid indentor and a sandwich structure is discussed in detail since it is very important to account for the local deformation in the contact zone in developing a model for predicting the contact force history. The mechanical behavior of foam and honeycomb core materials is reviewed along with experimental results and models for predicting the contact law between a smooth indentor and a sandwich structure. The development of mathematical models for predicting the contact force history and the overall response of the structure is also discussed. Finally we review the failure mechanisms involved in impact damage development, the parameters affecting damage size, and the residual properties of sandwich structures. This review article has 85 references.
Boundary Element Formulations in Fracture Mechanics
Authors: Aliabadi M. H.
Published: April 2009

This article reviews advances in the application of boundary element methods (BEM) to fracture mechanics which have taken place over the last 25 years. Applications discussed include linear, nonlinear and transient problems. Also reviewed are contributions using the indirect boundary element formulations. Over this period the method has emerged as the most efficient technique for the evaluation of stress intensity factors (SIF) and crack growth analysis in the context of linear elastic fracture mechanics (LEFM). Much has also been achieved in the application to dynamic fracture mechanics. This review article contains 289 references.
Boundary Element Methods in Dynamic Analysis: Part II (1986-1996)
Authors: Beskos Dimitri E.
Published: April 2009

A review of boundary element methods for the numerical solution of elastodynamic problems covering the period 1986-1996 is presented. It is a continuation of a review article on the same subject by the same author which appeared previously in Applied Mechanics Reviews (AMR 40(1) 1-23 (Jan 1987) Reprint No AMR015). Integral formulations and their advanced numerical treatment in both frequency and time domains from the direct boundary element method viewpoint are described. They cover two - and three - dimensional cases as well as the anti-plane case of linear elastodynamics under harmonic or transient disturbances. Indirect formulations, boundary methods, T-matrix methods, symmetric formulations, dual reciprocity boundary element methods and hybrid schemes combining boundary with finite elements are also described. All these boundary element methodologies are applied to: i) wave propagation analysis including wave propagation due to external loads, wave diffraction by surface or subsurface irregularities and cracks and crack propagation; ii) dynamic analysis of structures including beams, membranes, plates and shells as well as two - and three - dimensional structures; iii) soil-structure interaction including foundation analysis, piles and underground structures; iv) fluid-structure interaction including structures inside fluids or containing fluids and dam-reservoir systems; and v) the special subjects of viscoelasticity, inhomogeneity, anisotropy, poroelasticity-thermoelasticity, large deformations, contact analysis, inverse scattering and optimum design and control. Finally, areas where further research is needed are identified. There are 1333 references.
Stress Resultant Geometrically Exact Shell Theory for Finite Rotations and Its Finite Element Implementation
Authors: Ibrahimbegovic´ Adnan
Published: April 2009

This article reviews the significant progress on shell problem theoretical foundation and numerical implementation attained over a period of the last several years. First, a careful consideration of the three-dimensional finite rotations is given including the choice of optimal parameters, their admissible variations and the much revealing relationship between different parameters. A non-conventional derivation of the stress resultant shell theory is presented, which makes use of the virtual work principle and local Cartesian frames. The presented derivation introduces no simplifying hypotheses regarding the shell balance equations, hence the resulting shell theory is referred to as being geometrically exact. The strain measures energy-conjugate to the chosen stress resultants are identified and the nature of the stress resultants with respect to the three-dimensional stress tensor is explained along with the resulting constitutive restrictions. Comments are made regarding a rather useful extension of the shell theory which accounts for the rotational degree of freedom about the director, the so-called drilling rotation. A linear shell theory is obtained as a very useful by-product of the present work, by linearizing the present nonlinear shell theory about the reference configuration. It is shown that this non-conventional approach not only clarifies an often confusing derivation of the linear shell theory, but also leads to a novel linear shell theory capable of delivering significantly improved results and essentially exact solutions to the standard linear benchmark problems. Another important aspect of the nonlinear shell problem solution, the finite element approximation of the shell theory, is also discussed. The model problem of assumed shear strain interpolation is used to illustrate that numerical implementation which preserves the salient features of the theoretical formulation often brings an improved final result. For the selected rotation parameterization and the finite element interpolation, the issues of the consistent linearization of the nonlinear shell problem are addressed. In a number of numerical simulations, the latter is proved to play a crucial role not only in ensuring the robust performance of the Newton solution procedure, but also in linear and nonlinear buckling problems of shells. Several directions for future research are pointed out and some contemporary works of special interest are listed. There are 127 references at the end of the article.
Temperature- and Pressure-Sensitive Luminescent Paints in Aerodynamics
Authors: Liu Tianshu , Campbell B. T. , Burns S. P. , Sullivan J. P.
Published: April 2009

This review article presents an overview of the current state of temperature- and pressure-sensitive luminescent paint techniques used in aerodynamic measurements. Topics include photophysical foundations, paint preparation and calibration, measurement systems, accuracy, and time response. Applications of the luminescent paint technique in aerodynamic testing are discussed and typical examples of current research are given. There are 112 references.
Guided Waves in Plates and Their Use in Materials Characterization
Authors: Chimenti D. E.
Published: April 2009

In this review article, the ultrasonic characterization of materials using guided plate waves and their usage to elucidate mechanical properties of plate-like structures is reviewed. The purpose here is to summarize and explain the large body of theoretical and experimental work in this developing field. It is also to gain a perspective on recent salient contributions and to analyze the current state of knowledge and practice in guided wave ultrasonics. Models of waves in plates are examined, as are the means to generate and detect them. Their application to several problems of current interest in materials characterization is treated in detail. In particular, composite materials and their inspection and characterization have been a major impetus in the development of guided wave methods. Techniques to inspect composites sensitively and reliably for defects and to probe their micromechanical behavior are a major focus of this article. Also considered are the characterization of adhesive bonds, the measurement of stress and texture, and the detection of defects using guided waves. This review article contains 362 references.
Recent Advances in Computational Thermostructural Analysis of Composite Plates and Shells With Strong Nonlinearities
Authors: Argyris John , Tenek Lazarus
Published: April 2009

The article presents some modern developments in computational technology for the nonlinear thermostructural analysis of laminated composite plates and shells of arbitrary geometry. Following a review of the current state of the art, it particularly emphasizes on new finite element methodologies that can be applied to the study of complex laminated shells both thermally and structurally using the same topology constructed via simple simplex triangular elements based on respective first-order lamination theories. Very high temperatures are imposed on some examples in order to demonstrate the high effect of nonlinearity. In addition, the authors want to prepare the ground for the advent of new high-temperature materials. For the numerical examples presented comparison with reference solutions is made where available. Thus the present overview intends to impact a continuing discussion on the unification and integration of thermal and structural analyses methods as they apply to large and complex high-temperature composite shell structures under combined thermal and mechanical loading. In this respect it also intends to contribute to the on-going efforts of integrating thermal and structural engineering codes and the development of suitable interfaces. Future research trends are also identified.
Heat Conduction in Composites: Homogenization and Macroscopic Behavior
Authors: Furman˜ski Piotr
Published: April 2009

The review article discusses methods of macroscopic averaging of heat conduction in composite materials that lead to models of homogenized, macroscopic behavior of these media. It is shown that essentially two continuum models are in use: 1) the effective medium and 2) the mixture. The ensemble averaging technique allows one to derive the constitutive relations for both models assuming Fourier-like conduction on the microstructure level of a composite. These constitutive relations contain effective, macroscopic properties of the composite material which can be forecast when properties of individual constituents, the form of thermal interaction at constituent interfaces, amount of each material and its distribution are known. For weakly varying mean temperature fields, thermal behavior of the composite is essentially the same as homogeneous media but, for stronger variation, a non-classical behavior is observed. This non-classical behavior can be associated either with space nonlocality and memory phenomena or with wall effects and, in some cases, with influence of local heat sources on the effective properties. Most of these effects are not well known and need further detailed studies. The article includes 158 references.
Eigenmode Analysis in Unsteady Aerodynamics: Reduced Order Models
Authors: Dowell Earl H. , Hall Kenneth C. , Romanowski Michael C.
Published: April 2009

In this article, we review the status of reduced order modeling of unsteady aerodynamic systems. Reduced order modeling is a conceptually novel and computationally efficient technique for computing unsteady flow about isolated airfoils, wings, and turbomachinery cascades. Starting with either a time domain or frequency domain computational fluid dynamics (CFD) analysis of unsteady aerodynamic or aeroacoustic flows, a large, sparse eigenvalue problem is solved using the Lanczos algorithm. Then, using just a few of the resulting eigenmodes, a Reduced Order Model of the unsteady flow is constructed. With this model, one can rapidly and accurately predict the unsteady aerodynamic response of the system over a wide range of reduced frequencies. Moreover, the eigenmode information provides important insights into the physics of unsteady flows. Finally, the method is particularly well suited for use in the active control of aeroelastic and aeroacoustic phenomena as well as in standard aeroelastic analysis for flutter or gust response. Numerical results presented include: 1) comparison of the reduced order model to classical unsteady incompressible aerodynamic theory, 2) reduced order calculations of compressible unsteady aerodynamics based on the full potential equation, 3) reduced order calculations of unsteady flow about an isolated airfoil based on the Euler equations, and 4) reduced order calculations of unsteady viscous flows associated with cascade stall flutter, 5) flutter analysis using the Reduced Order Model. This review article includes 25 references.
Bayonet Tube Heat Exchanger
Authors: Lock G. S. H. , Minhas Harpal
Published: April 2009

This review article provides an overview and assessment of the bayonet tube heat exchanger in its concentric tube configuration. The article begins with a brief historical sketch of its use in three main contexts: in the process industries, especially in waste heat recovery; in geotechnical engineering, in permafrost stabilization; and in medicine, especially in cryosurgery. A conceptual outline describing the main heat transfer features of the device in counterflow, parallel flow, and cross flow situations follows. Particular attention is paid to the implications of thermal coupling between the inner tube flow, the annular (return) flow and the external fluid flow. The main text is divided into two parts: Experimental studies and Theoretical studies. Each of these is subdivided into two complementary sections: hydraulic studies, in which the emphasis is placed on fluid flow characteristics, especially in the U-bend at the end of the tube; and thermal studies, emphasizing the convective heat transfer characteristics. Each subsection is further divided to permit separate discussion of laminar, transitional and turbulent flow under steady, single-phase conditions. Experimental data are systematically compared with numerical predictions to provide a comprehensive survey of the effect of the independent variables (flow rate, tube geometry, and fluid properties) on the dependent variables (pressure drop, heat transfer rate). Experimental and numerical data are combined to develop empirical correlations for pressure drop and heat transfer. The final section examines the above findings to uncover the limitations of our current knowledge and thereby suggest profitable avenues for future research. There are 47 references listed at the end of the article.
Explicit and Implicit Methods for Design Sensitivity Analysis of Nonlinear Structures Under Dynamic Loads
Authors: Arora Jasbir S. , Dutta Abhijit
Published: April 2009

Explicit and implicit methods for design sensitivity analysis of nonlinear structures subjected to transient dynamic loads are described. The direct differentiation method is used to calculate the sensitivities. Elastic and elasto-plastic problems undergoing large deformation are treated in the formulation. The explicit method is quite straightforward to implement for analysis as well as design sensitivity analysis: knowing all the quantities at time t, one updates the quantities for the next time point without solution of any linear system of equations, or any iterations. For the implicit method, the effective stiffness matrix for the sensitivity equation is different from that for the analysis phase due to inclusion of large deformation in the formulation. A numerical procedure to integrate the equation is proposed which uses the symmetric effective stiffness matrix from the analysis phase. Although the sensitivity analysis problem is linear, the procedure requires iterations for sensitivity calculations at each time step, as for the analysis phase. The implicit method is implemented using the pre-conditioned conjugate gradient iterative solution scheme. Numerical results for sensitivities indicate the implicit method to be more accurate than the explicit method for transient elastoplastic problems. However, the explicit method is substantially more efficient than the implicit method.
Rotor Design and Optimization in Internal Lobe Pumps
Authors: Mimmi Giovanni , Pennacchi Paolo
Published: April 2009

The topic of this paper is the design of internal lobe pumps and their optimization which is based on specific performance indexes. Internal lobe pumps can be classified as different types depending on the shape of the lobe of the outer rotor. First, the design of internal lobe pumps with elliptical, sinusoidal, and polycircular lobe profiles is considered. The latter is a new type of lobe profile with special shape whose curvature follows a definite function. Then we introduce the performance indexes used for the comparison. Some of these indexes, such as the flow rate irregularity, are commonly used for performance comparison, while others, such as the specific slipping and the rotor curvature, are particularly suitable in this case. The comparisons are made with the circular type that had been analyzed by the authors in previous papers (see eg, Mimmi, Pannacchi, and Savi (1996), Internal Lobe Pump Design, Mechanics in design - Proc CSME Forum ’96, SA Meguid (ed), Toronto, Ontario, Canada). It is not easy to univocally state the superiority of one type with respect to the others, however, it is possible to notice that elliptical and polycircular types are comparable to the circular ones in terms of flow rate irregularity, but have improved performance in terms of specific slipping and rotor curvature.
Sensitivity Analysis of Elastoplastic Structures by Using Explicit Integration Method
Authors: Ohsaki Makoto
Published: April 2009

An algorithm is presented for sensitivity analysis of responses of an elastoplastic distributed parameter structure subjected to cyclic loading conditions. The structure is modeled by the finite element method, where an isoparametric element is used. The responses are found by using an explicit integration method incorporating higher-order differential coefficients with respect to the path parameter. All the governing equations are differentiated with respect to the design variables, and sensitivity coefficients of the responses are updated incrementally at each step. The accurate sensitivity coefficients are calculated for the value of the path parameter at the yield or unloading point. Since the algorithm is totally consistent with that of response analysis, the calculated sensitivity coefficients agree within good accuracy with those by the finite difference method.