Written for researchers and advanced students the book exhibits a combination of various methods and tools required to describe the complexity of the chemical and physical behaviour of fluid surfaces. The common denominator for all the contributions presented here is the simultaneous use of concepts from surface chemistry and physics and from hydrodynamics where external force fields can be introduced. Theoretical and experimental work is equally represented. Most of the basic problems in the area of nonequilibrium multiphase systems have not yet received extensive treatment. This volume should be a reference for physicists, physico-chemists, and chemical engineers and will serve as a jumping-off point for new directions and new points of view.

Modelling of hydrological rainfall-runoff processes is facilitated by the application of the systemtheoretical approach to linear, nonlinear and stochastic models. To this purpose, the variables involved in methods for determinating areal precipitation and baseflow separation are discussed. The convolution theorem in the theory of linear systems and the mathematical transform technique (Laplace-, Z-transformation) are used to identify characteristics of the watershed, and simulate hydrological processes. To support the calculation of model output functions, computer programs are included in the text. This volume is suitable as a text for hydrology courses at universities or engineering academies.

Along with almost a hundred research communications this volume contains six invited lectures of lasting value. They cover modeling in plasma dynamics, the use of parallel computing for simulations and the applications of multigrid methods to Navier-Stokes equations, as well as other surveys on important techniques. An inaugural talk on computational fluid dynamics and a survey that relates dynamical systems, turbulence and numerical solutions of the Navier-Stokes equations give an exciting view on scientific computing and its importance for engineering, physics and mathematics.

Two-fluid dynamics is a challenging subject rich in physics and prac tical applications. Many of the most interesting problems are tied to the loss of stability which is realized in preferential positioning and shaping of the interface, so that interfacial stability is a major player in this drama. Typically, solutions of equations governing the dynamics of two fluids are not uniquely determined by the boundary data and different configurations of flow are compatible with the same data. This is one reason why stability studies are important; we need to know which of the possible solutions are stable to predict what might be observed. When we started our studies in the early 1980's, it was not at all evident that stability theory could actu ally work in the hostile environment of pervasive nonuniqueness. We were pleasantly surprised, even astounded, by the extent to which it does work. There are many simple solutions, called basic flows, which are never stable, but we may always compute growth rates and determine the wavelength and frequency of the unstable mode which grows the fastest. This proce dure appears to work well even in deeply nonlinear regimes where linear theory is not strictly valid, just as Lord Rayleigh showed long ago in his calculation of the size of drops resulting from capillary-induced pinch-off of an inviscid jet.

This book covers a wide area of topics, from fundamental theories to industrial applications. It serves as a useful reference for everyone interested in computational modeling of partial differential equations pertinent primarily to aeronautical applications. The reader will find three survey articles on the present state of the art in numerical simulation of the transition to turbulence, in design optimization of aircraft configurations, and in turbulence modeling. These are followed by carefully selected and refereed articles on algorithms and their applications, on design methods, on grid adaption techniques, on direct numerical simulations, and on parallel computing, and much more.

This volume contains contributions to the BRITE-EURAM 3rd Framework Programme ETMA and extended articles of the TMA-Workshop. It focusses on turbulence modelling techniques suitable to use in typical flow configurations, with emphasis on compressibility effects and inherent unsteadiness. These methodologies are applied to the Navier-Stokes equations, involving various turbulence modelling levels from algebraic to RSM. Basic turbulent flows in aeronautics are considered; mixing layers, wall-flows (flat-plate, backward-facing step, ramp, bump), and more complex configurations (bump, aerofoil). A critical assessment of the turbulence modelling performances is offered, based on previous results and on the experimental data-base of this research programme. The ETMA results figure in the data-base constituted by all partners and organized by INRIA

This volume contains the papers of a German symposium dealing with research and project work in numerical and experimental aerodynamics and fluidmechanics for aerospace and other applications. It gives a broad overview over the ongoing work in this field in Germany.

This volume brings together five contributions to mathematical fluid mechanics, a classical but still very active research field which overlaps with physics and engineering. The contributions cover not only the classical Navier-Stokes equations for an incompressible Newtonian fluid, but also generalized Newtonian fluids, fluids interacting with particles and with solids, and stochastic models. The questions addressed in the lectures range from the basic problems of existence of weak and more regular solutions, the local regularity theory and analysis of potential singularities, qualitative and quantitative results about the behavior in special cases, asymptotic behavior, statistical properties and ergodicity.

Liquid helium has been studied for its intrinsic interest through much of the 20th century. In the past decade, much has been learned about heat transfer in liquid helium because of the need to cool superconducting magnets and other devices. The topic of the Seventh Oregon Conference on Low Temperature Physics was an applied one, namely the use of liquid and gaseous helium to generate high Reynolds number flows. The low kinematic viscosity of liquid helium automatically makes high Reynolds numbers accessible and the question addressed in this conference was to explore various possibilities to see what practical devices might be built using liquid or gaseous helium. There are a number of possibilities: construction of a wind tunnel using critical helium gas, free surface testing, low speed flow facilities using helium I and helium ll. At the time of the conference, most consideration had been given to the last possibility because it seemed both possible and useful to build a flow facility which could reach unprecedented Reynolds numbers. Such a device could be useful in pure research for studying turbulence, and in applied research for testing models much as is done in a water tunnel. In order to examine these possibilities in detail, we invited a wide range of experts to Eugene in October 1989 to present papers on their own specialties and to listen to presentations on the liquid helium proposals.

The decision of the General Assembly of the International Union of Theoretical and Applied Mechanics to organize a Symposium on Dynamics of Slender Vortices was greeted with great enthusiasm. The acceptance of the proposal, forwarded by the Deutsches Komitee fiir Mechanik (DEKOMECH) signalized, that there was a need for discussing the topic chosen in the frame the IUTAM Symposia offer. Also the location of the symposium was suitably chosen: It was decided to hold the symposium at the RWTH Aachen, where, years ago, Theodore von Karman had worked on problems related to those to be discussed now anew. It was clear from the beginning of the planning, that the symposium could only be held in the von Karman-Auditorium ofthe Rheinisch-Westfalische Technische Hochschule Aachen, a building named after him. The symposium was jointly organized by the editors of this volume, strongly supported by the local organizing committee. The invitations of the scientific committee brought together scientists actively engaged in research on the dynamics of slender vortices. It was the aim of the committee to have the state of the art summarized and also to have the latest results of specific problems investigated communicated to the participants of the symposium. The topics chosen were asymptotic theories, numerical methods, vor tices in shear layers, interaction of vortices, vortex breakdown, vortex sound, and aircraft and helicopter vortices.

This volume contains a selection of the papers presented at the Fourth Symposium on Numerical and Physical Aspects of Aerodynamic Flows, which was held at the California State University, Long Beach, from 16-19 January 1989. It includes the Stewartson Memorial Lecture of Professor J. H. Whitelaw, and is divided into three parts. The first is a collection of papers that describe the status of current technology in two- and three-dimensional steady flows, the second deals with two- and three-dimensional unsteady flows, and the papers in the third address stability and transition. Each of the three parts begins with an overview of current research, as described in the following chapters. The individual papers are edited versions of the selected papers originally submitted to the symposium. Four years have passed since the Third Symposium, and certain trends be come clear if one compares the papers contained in this volume with those of previous volumes. There are more three- than two-dimensional problems consid ered in Part 1 and the latter address more difficult problems than in the past, for example, the extension to higher angles of attack, to transonic flow, to leading edge ice accretion, and to thick hydrofoils. The large number of papers in the first part reflects the emphasis of current research and development and the needs of industry."

This critical overview describes fluid flow driven by the thermocapillary effect in models of crystal growth. Simple models are the floating-zone technique and the open-boat technique. Basic equations, boundary layer scaling, stability analysis, pattern formation and additional buoyancy are discussed. Particular emphasis is given to the understanding of the physics of flow. This reference book gives a state-of-the-art report and reviews the literature available.

Inelastic scattering of X-rays with very high energy resolution has finally become possible thanks to a new generation of high-intensity X-ray sources. This development marks the end to the traditional belief that low energy excitations like lattice vibrations cannot be resolved directly with X-rays: Inelastic scattering experiments allow to observe directly the small energy shifts of the photons. Studies of lattice vibrations, of excitations in molecular crystals, of collective excitations in liquids and electronic excitations in crystals demonstrating the broad applicability and power of this new technology are discussed in this book. The progress in this field opens up fantastic new research areas not only in physics but also in other disciplines such as materials science, biology and chemistry.

Over the last few years it has become apparent that fluid turbulence shares many common features with plasma turbulence, such as coherent structures and self-organization phenomena, passive scalar transport and anomalous diffusion. This book gathers very high level, current papers on these subjects. It is intended for scientists and researchers, lecturers and graduate students because of the review style of the papers.

Based on his over forty years of research and teaching, John C. Wyngaard's textbook is an excellent up-to-date introduction to turbulence in the atmosphere and in engineering flows for advanced students, and a reference work for researchers in the atmospheric sciences. Part I introduces the concepts and equations of turbulence. It includes a rigorous introduction to the principal types of numerical modeling of turbulent flows. Part II describes turbulence in the atmospheric boundary layer. Part III covers the foundations of the statistical representation of turbulence and includes illustrative examples of stochastic problems that can be solved analytically. The book treats atmospheric and engineering turbulence in a unified way, gives clear explanation of the fundamental concepts of modeling turbulence, and has an up-to-date treatment of turbulence in the atmospheric boundary layer. Student exercises are included at the ends of chapters, and worked solutions are available online for use by course instructors.

We here attempt to give a complete but concise treatment of the theory of steady viscometric flows of simple (non-Newtonian) fluids and to use that theory to discuss the design and interpretation of ex periments. We are able to present the theory with less mathematical machinery than was used in our original papers, partly because this Tract has more limited aims than those papers, and partly because we employ a method, found by Noll and published here for the first time, for dealing with visco metric flows without the apparatus of rela tive Cauchy-Green tensors and reduced constitutive equations. To make the theory accessible to students not familiar with modern mathematics, we have added to our Tract an appendix explaining some of the mathe matical concepts essential to continuum physics. Pittsburgh, July 1965 BERNARD D. COLEMAN HERSHEL MARKOVITZ WALTER NOLL CONTENTS I. Introduction page 1. Limitations of the Classical Theory of Navier and Stokes. 1 5 2. Incompressible Simple Fluids. . . . . . . . . . . . 3. Plan and Scope of this Monograph . . . . . . . . . 7 II. Theory of Incompressible Simple Fluids 4. Kinematics. . . . . . . . . . . . 10 5. The Dynamical Equations . . . . . . . . . . . 12 6. The Principle of Material Objectivity . . . . . . 14 7. The Definition of an Incompressible Simple Fluid . 17 8. Static Behavior of Simple Fluids . . . . . . . . 19 III. General Theory of Viscometric Flows 9. The Kinematics of Simple Shearing Flow 21 10. The Viscometric Functions . . . . . . . . . . 22 11. The Dynamics of Simple Shearing Flow; Viscosity 26 12. The Definition of a Viscometric Flow 29 13. Curvilineal Flows. . . . . . . . 30 1. Kinematical Description . . . .

This IMA Volume in Mathematics and its Applications PARTICULATE FLOWS: PROCESSING AND RHEOLOGY is based on the proceedings of a very successful one-week workshop with the same title, which was an integral part of the 1995-1996 IMA program on "Mathematical Methods in Materials Science." We would like to thank Donald A. Drew, Daniel D. Joseph, and Stephen L. Passman for their excellent work as organizers of the meeting. We also take this opportunity to thank the National Science Foun dation (NSF), the Army Research Office (ARO) and the Office of Naval Research (ONR), whose financial support made the workshop possible. A vner Friedman Robert Gulliver v PREFACE The workshop on Particulate Flows: Processing and Rheology was held January 8-12, 1996 at the Institute for Mathematics and its Applications on the University of Minnesota Twin Cities campus as part of the 1995- 96 Program on Mathematical Methods in Materials Science. There were about forty participants, and some lively discussions, in spite of the fact that bad weather on the east coast kept some participants from attending, and caused scheduling changes throughout the workshop. Heterogeneous materials can behave strangely, even in simple flow sit uations. For example, a mixture of solid particles in a liquid can exhibit behavior that seems solid-like or fluid-like, and attempting to measure the "viscosity" of such a mixture leads to contradictions and "unrepeatable" experiments. Even so, such materials are commonly used in manufacturing and processing."

The Second Symposium on Numerical and Physical Aspects of Aerodynamic Flows was held at California State University, Long Beach, from 17 to 20 January 1983. Forty-eight papers were presented, including Keynote Lec tures by A. M. 0. Smith and J. N. Nielsen, in ten technical sessions which were supplemented and complemented by two Open Forum Sessions, involving a further sixteen technical presentations and a Panel Discussion on the "Identification of priorities for the development of calculation methods for aerodynamic bodies. " The Symposium was attended by 120 research workers from nine countries and, as in the First Symposium, provided a basis for research workers to communicate, to assess the present status of the subject and to formulate priorities for the future. In contrast to the First Symposium, the papers and discussion were focused more clearly on the subject of flows involving the interaction between viscous and inviscid regions and the calculation of pressure, velocity and temperature characteristics as a function of geometry, angle of attack and Mach number. Rather more than half the papers were concerned with two-dimensional configurations and the remainder with wings, missiles and ships. This volume presents a selection of the papers concerned with two dimensional flows and a review article specially prepared to provide essen tial background information and link the topics of the individual papers."

Computational Fluid Dynamics (CFD) has been applied extensively to great benefit in the food processing sector. Its numerous applications include: predicting the gas flow pattern and particle histories, such as temperature, velocity, residence time, and impact position during spray drying;modeling of ovens to provide information about temperature and airflow pattern throughout the baking chamber to enhance heat transfer and in turn final product quality; designing hybrid heating ovens, such as microwave-infrared, infrared-electrical or microwave-electrical ovens for rapid baking; model the dynamics of gastrointestinal contents during digestion based on the motor response of the GI tract and the physicochemical properties of luminal contents; retort processing of canned solid and liquid foods for understanding and optimization of the heat transfer processes. This Brief will recapitulate the various applications of CFD modeling, discuss the recent developments in this field, and identify the strengths and weaknesses of CFD when applied in the food industry. "

The study of optimal shape design can be arrived at by asking the following question: "What is the best shape for a physical system?" This book is an applications-oriented study of such physical systems; in particular, those which can be described by an elliptic partial differential equation and where the shape is found by the minimum of a single criterion function. There are many problems of this type in high-technology industries. In fact, most numerical simulations of physical systems are solved not to gain better understanding of the phenomena but to obtain better control and design. Problems of this type are described in Chapter 2. Traditionally, optimal shape design has been treated as a branch of the calculus of variations and more specifically of optimal control. This subject interfaces with no less than four fields: optimization, optimal control, partial differential equations (PDEs), and their numerical solutions-this is the most difficult aspect of the subject. Each of these fields is reviewed briefly: PDEs (Chapter 1), optimization (Chapter 4), optimal control (Chapter 5), and numerical methods (Chapters 1 and 4).

It has become almost a cliche to preface one's remarks about asymptotic tech niques with the statement that only a very few special problems in diffrac tion theory (be it electromagnetic, acoustic, elastic or other phenomena) are possessed of closed form solutions, but as with many cliches, this is because it is true. One only has to scan the literature to see the large amount of effort (both human and computer) expended to solve diffraction problems involving complicated geometries which do not permit such simplifications as separation of variables, It was a desire for techniques more straightforward than frontal numerical assaults, as well as for a theory \ hich \ ould explain the basic physical phenomena involved, which stimulated research into asymptot ic methods. Geometrical optics (GO) and, now, even Keller's geometrical theory of dif fraction (GTD) have been with us for some time, and have become standard tools in the analysis of high-frequency wave phenomena, Of course, it was always recognized that these approaches broke down in certain regions: GO in the shadow region; GTD along shadow boundaries and caustics. One remedy for these defects is to construct an expansion, based upon a more general ansatz than GO or GTD, which is made to be valid in one or more of the areas where GO or GTD break down."

This book describes several finite-difference techniques developed recently for the numerical solution of fluid equations. Both convective (hyperbolic) equations and elliptic equations (of Poisson's type) are discussed. The em phasis is on methods developed and in use at the Naval Research Laboratory, although brief descriptions of competitive and kindred techniques are included as background material. This book is intended for specialists in computational fluid dynamics and related subjects. It includes examples, applications and source listings of program modules in Fortran embodying the methods. Contents Introduction 1 (D. L. Book) 2 Computational Techniques for Solution of Convective Equations 5 (D. L. Book and J. P. Boris) 2. 1 Importance of Convective Equations 5 2. 2 Requirements for Convective Equation Algorithms 7 2. 3 Quasiparticle Methods 10 2. 4 Characteristic Methods 13 2. 5 Finite-Difference Methods 15 2. 6 Finite-Element Methods 20 2. 7 Spectral Methods 23 3 Flux-Corrected Transport 29 (D. L. Book, J. P. Boris, and S. T. Zalesak) 3. 1 Improvements in Eulerian Finite-Difference Algorithms 29 3. 2 ETBFCT: A Fully Vectorized FCT Module 33 3. 3 Multidimensional FCT 41 4 Efficient Time Integration Schemes for Atmosphere and Ocean Models 56 (R. V. Madala) 4. 1 Introduction 56 4. 2 Time Integration Schemes for Barotropic Models 58 4. 3 Time Integration Schemes for Baroclinic Models 63 4. 4 Extension to Ocean Models 70 David L. Book, Jay P. Boris, and Martin J. Fritts are from the Laboratory for Computational Physics, Naval Research Laboratory, Washington, D. C."

This volume contains the proceedings of the symposium held on Friday 6 July 1990 at the University Pierre et Marie Curie (Paris VI), France, in honor of Professor Henri Cabannes on the occasion of his retirement. There were about one hundred participants from nine countries: Canada, France, Germany, Italy, Japan, Norway, Portugal, the Netherlands, and the USA. Many of his past students or his colleagues were among the participants. The twenty-six papers in this volume are written versions submitted by the authors and cover almost all the fields in which Professor Cabannes has actively worked for more than forty-five years. The papers are presented in four chapters: classical kinetic theory and fluid dynamics, discrete kinetic theory, applied fluid mechanics, and continuum mechanics. The editors would like to take this opportunity to thank the generous spon sors of the symposium: the University Pierre et Marie Curie, Commissariat a l'Energie Atomique (especially Academician R. Dautray and Dr. N. Camarcat) and Direction des Recherches et Etudes Techniques (especially Professor P. Lallemand). Many thanks are also due to all the participants for making the symposium a success. Finally, we thank Professor W. Beiglbock and his team at Springer-Verlag for producing this volume.

Der Band enthalt den Abschlussbericht des DFG-Schwerpunktprogramms "Flusssimulation mit Hochstleistungsrechnern." Es fuhrt die Arbeiten fort, die schon als Band 38 in der Reihe "Notes on Numerical Fluid Mechanics" erschienen sind.Work is reported, which was sponsored by the Deutsche Forschungsgemeinschaft from 1993 to 1995. Scientists from numerical mathematics, fluid mechanics, aerodynamics, and turbomachinery present their work on flow simulation with massively parallel systems, on the direct and large-eddy simulation of turbulence, and on mathematical foundations, general solution techniques and applications. Results are reported from benchmark computations of laminar flow around a cylinder, in which seventeen groups participated."

Modelling transport and mixing by turbulence in complex flows are huge challenges for computational fluid dynamics (CFD). This highly readable book introduces readers to modelling levels that respect the physical complexity of turbulent flows. It examines the hierarchy of Reynolds-averaged Navier-Stokes (RANS) closures in various situations ranging from fundamental flows to three-dimensional industrial and environmental applications. The general second-moment closure is simplified to linear eddy-viscosity models, demonstrating how to assess the applicability of simpler schemes and the conditions under which they give satisfactory predictions. The principal changes for the second edition reflect the impact of computing power: a new chapter devoted to unsteady RANS and another on how large-eddy simulation, LES, and RANS strategies can be effectively combined for particular applications. This book will remain the standard for those in industry and academia seeking expert guidance on the modelling options available, and for graduate students in physics, applied mathematics and engineering entering the world of turbulent flow CFD.