Page 18 - Fluid-Structure Interactions Slender Structure and Axial Flow (Volume 1)

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Introduction

1.1 GENERAL OVERVIEW
This book deals with the dynamics of slender, mainly cylindrical or quasi-cylindrical,
bodies in contact with axial flow - such that the structure either contains the flow
or is immersed in it, or both. Dyrzamics is used here in its genetic sense, including
aspects of srabiliry, thus covering both self-excited and free or forced motions
associated with fluid-structure interactions in such configurations. Indeed, flow-induced
instabilities - instabilities in the linear sense, namely, divergence and flutter - are a
major concern of this book. However, what is rather unusual for books on flow-induced
vibration, is that considerable attention is devoted to the nonlinear behaviocrr of such
systems, e.g. on the existence and stability of limit-cycle motions, and the possible
existence of chaotic oscillations. This necessitates the introduction and utilization of some
of the tools of modem dynamics theory.
Engineering examples of slender systems interacting with axial flow are pipes and other
flexible conduits containing flowing fluid, heat-exchanger tubes in axial flow regions of
the secondary fluid and containing internal flow of the primary fluid, nuclear reactor
fuel elements, monitoring and control tubes, thin-shell structures used as heat shields in
aircraft engines and thermal shields in nuclear reactors, jet pumps, certain types of valves
and other components in hydraulic machinery, towed slender ships, barges and submarine
systems, etc. Physiological examples may be found in the pulmonary and urinary systems
and in haemodynamics.
However, much of the work in this area has been, and still is, ‘curiosity-driven’,’
rather than applications-oriented. Indeed, although some of the early work on stability of
pipes conveying fluid was inspired by application to pipeline vibrations, it soon became
obvious that the practical applicability of this work to engineering systems was rather
limited. Still, the inherent interest of the extremely varied dynamical behaviour which
this system is capable of displaying has propelled researchers to do more and more
work - to the point where in a recent review (PaYdoussis & Li 1993) over 200 papers
were cited in a not-too-exhaustive bibliography.$ In the process, this topic has become
a new paradigm in dynamics, i.e. a new model dynamical problem, thus serving two
purposes: (i) to illustrate known dynamical behaviour in a simple and convincing manner;

‘With the present emphasis on utilitarianism in engineering and even science research, the characterization
of a piece of work as ‘curiosity-driven’ stigmatizes it and, in the minds of some, brands it as being ‘useless’.
Yet, some of the highest achievements of the human mind in science (including medical and engineering
science) have indeed been curiosity-driven; most have ultimately found some direct or indirect, and often very
important, practical application.
*See also Becker (1981) and Paidoussis (1986a. 1991).

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