This self-contained book provides an introduction to the flow-oscillator modeling of vortex-induced bluff-body oscillations. One of the great challenges in engineering science also happens to be one of engineering design - the modeling, analysis and design of vibrating structures driven by fluid motion. The literature on fluid-structure interaction is vast, and it can be said to comprise a large fraction of all papers published in the mechanical sciences. This book focuses on the vortex-induced oscillations of an immersed body, since, although the importance of the subject has long been known, it is only during the past fifty years that there have been concerted efforts to analytically model the general behavior of the coupling between vortex shedding and structural oscillations. At the same time, experimentalists have been gathering data on such interactions in order to help define the various regimes of behavior. This data is critical to our understanding and to those who develop analytical models, as can be seen in this book. The fundamental bases for the modeling developed in this book are the variational principles of analytical dynamics, in particular Hamilton's principle and Jourdain's principle, considered great intellectual achievements on par with Newton's laws of motion. Variational principles have been applied in numerous disciplines, including dynamics, optics and quantum mechanics. Here, we apply variational principles to the development of a framework for the modeling of flow-oscillator models of vortex-induced oscillations.

The purpose of this monograph is to show how a compliant offshore structure in an ocean environment can be modeled in two and three di mensions. The monograph is divided into five parts. Chapter 1 provides the engineering motivation for this work, that is, offshore structures. These are very complex structures used for a variety of applications. It is possible to use beam models to initially study their dynamics. Chapter 2 is a review of variational methods, and thus includes the topics: princi ple of virtual work, D'Alembert's principle, Lagrange's equation, Hamil ton's principle, and the extended Hamilton's principle. These methods are used to derive the equations of motion throughout this monograph. Chapter 3 is a review of existing transverse beam models. They are the Euler-Bernoulli, Rayleigh, shear and Timoshenko models. The equa tions of motion are derived and solved analytically using the extended Hamilton's principle, as outlined in Chapter 2. For engineering purposes, the natural frequencies of the beam models are presented graphically as functions of normalized wave number and geometrical and physical pa rameters. Beam models are useful as representations of complex struc tures. In Chapter 4, a fluid force that is representative of those that act on offshore structures is formulated. The environmental load due to ocean current and random waves is obtained using Morison's equa tion. The random waves are formulated using the Pierson-Moskowitz spectrum with the Airy linear wave theory."

This Symposium, and these Proceedings, provided a forum for the latest thinking in analytical, computational and experimental modelling of structures interacting with fluid environments. A meaningful and lasting dialogue was facilitated between leading researchers in the different component disciplines. It is intended that, through these dialogues, multidisciplinary linkages will be establishes leading to integrated approaches to modelling the complex, nonlinear interactions between fluids and structures. Examples of classes of interactions that may be addressed in this Symposium include ocean structures, fluid conveying structures, and aerospace structures. The energy transfer processes are inherently nonlinear in all aspects of the behaviour. The important class of vortex-induced oscillations has regions of lock-in, where the structural natural frequencies rather than the fluid velocity govern the shedding, and there exists hysteretic behaviour.
A large body of engineering and engineering science is concerned about fluid-structure interactions. Yet there are many unanswered questions about the underlying physics, so much so that a great deal of empiricism remains. Much of this empiricism can be traced to the relative lack of detailed collaboration between the fluid and structural mechanics communities studying these interactions. Generally, it has been that structural mechanicians would place extensive effort into the structural model, while a simple oscillator represented fluid motions. Conversely, fluid mechanicians placed most of their modelling efforts into the fluid, often considering the structure to be a rigid single degree of freedom oscillator. While such studies havesignificantly increased understanding, it appears that the next breakthroughs in the field need to be modelled at a comparable lever of accuracy.
The real fluid-structure system is one of complex exchanges of forces and energies, resulting in highly nonlinear behaviours. The ability to model, solve and test fully coupled fluid-structure systems portends a rich and profound understanding. In fact, recent research efforts have indeed started to focus on the development of fully coupled models. This Symposium is therefore a response to these new and exciting developments in the field.

This plenary paper and the accompanying presentation have highlighted field problems involving fluid-structure interaction over a wide span of Navy operations. Considering the vast size and versatility of the Navy's inventory, the cases presented represent examples of a much larger problem. But even this limited set provides sufficient evidence that fluid-structure interaction does hinder the Navy's ability to accomplish its missions. This survey has also established that there are no accurate and generally applicable design tools for addressing these problems. In the majority of cases the state-of-practice is to either make ad-hoc adjustments and estimates based on historical evidence, or conduct expensive focused tests directed at each specific problem and/or candidate solution. Unfortunately, these approaches do not provide insight into the fundamental problem, and neither can be considered reliable regarding their likelihood of success. So the opportunities for applying computational fluid-structure interaction modeling to Navy problems appear limitless. Scenarios range from the "simple" resonant strumming of underwater and in-air cables, to the "self-contained" flow field and vibration of aircraft/ordnance bodies at various Mach numbers, to violent underwater transient detonations and local hull structural collapse. Generally applicable and computationally tractable design-oriented models for these phenomena are of course still far in the future. But the Navy has taken the first steps in that direction by sponsoring specialized numerical models, validation experiments tailored for specific applications, and conferences such as this one."

The expansion of our civilization to the Moon and beyond is now within our reach, technically, intellectually and financially. Apollo was not our last foray into the Solar System and already science fiction is finding it difficult to keep ahead of science and engineering fact. In 1807, few people anticipated the Wright Brothers' human flight a hundred years later. In 1869, only science fiction writers would have suggested landing people on the Moon in 1969. Similarly, other great inventions in mechanics and in electronics were not envisaged and therefore the technologies to which those inventions gave birth were only foreseen by a tiny group of visionaries.

Designing a habitat for the lunar surface? You will need to know more than structural engineering. There are the effects of meteoroids, radiation, and low gravity. Then there are the psychological and psychosocial aspects of living in close quarters, in a dangerous environment, far away from home. All these must be considered when the habitat is sized, materials specified, and structure designed. This book provides an overview of various concepts for lunar habitats and structural designs and characterizes the lunar environment - the technical and the nontechnical. The designs take into consideration psychological comfort, structural strength against seismic and thermal activity, as well as internal pressurization and 1/6 g. Also discussed are micrometeoroid modeling, risk and redundancy as well as probability and reliability, with an introduction to analytical tools that can be useful in modeling uncertainties.