HYDRODYNAMIC PROPULSION AND ITS OPTIMIZATION ANALYTIC THEORY Hydrodynamic propulsion has been of major interest ever since craft took to the water. In the course of time, many attempts have been made to invent, develop, or to improve hydrodynamic propulsion devices. Remarkable achievements in this field were made essentially by experienced individuals, who were in need of reliable propulsion units such as paddle wheels, sculling devices, screw propellers, and of course, sails. The problem of minimizing the amount of input energy for a prescribed effective output was first investigated seriously at the beginning of this century. In 1919, BETZ presented a paper on air-screw propellers with minimum consumption of energy which could be applied to ship-screw propellers also. Next, attempts were made to optimize hydrodynamic propulsion units. Ensuing investigations concerned the optimization of the hydrodynamic system: ship-propeller. The first simple theory of ship propulsion which was presented considered more or less only thrust augmentation, wake processing and modification of propeller characteristics when operating behind the ships hull. This theory has been little improved meanwhile and is still useful, particularly with regard to practical ship design and for evaluating results of ship model tests. However, this theory is not adequate for optimization procedures necessary for high-technology propulsion, particularly for ship propellers utilizing propulsion improving devices such as tip end plates or tip fins at the propeller blades, spoilers in front of the propeller, asymmetrical stern etc.
This text presents the techniques for a wide set of applications, ranging from the problems of size and shape optimization (historically the first to be studied) to topology and material optimization. Structural models are considered that use both discrete and finite elements. Structural materials can be classical or new. Emerging methods are also addressed, such as automatic differentiation, intelligent structures optimization, integration of structural optimization in concurrent engineering environments, and multidisciplinary optimization.
Proceedings of the IUTAM Symposium held in Stuttgart, Germany, 26–31 March 1995
Author: D. Bestle
Publisher: Springer Science & Business Media
Category: Technology & Engineering
The International Union of Theoretical and Applied Mechanics (IUTAM) initiated and sponsored an International Symposium on Optimization of Mechanical Systems held in 1995 in Stuttgart, Germany. The Symposium was intended to bring together scientists working in different fields of optimization to exchange ideas and to discuss new trends with special emphasis on multi body systems. A Scientific Committee was appointed by the Bureau of IUTAM with the following members: S. Arimoto (Japan) EL. Chernousko (Russia) M. Geradin (Belgium) E.J. Haug (U.S.A.) C.A.M. Soares (Portugal) N. Olhoff (Denmark) W.O. Schiehlen (Germany, Chairman) K. Schittkowski (Germany) R.S. Sharp (U.K.) W. Stadler (U.S.A.) H.-B. Zhao (China) This committee selected the participants to be invited and the papers to be presented at the Symposium. As a result of this procedure, 90 active scientific participants from 20 countries followed the invitation, and 49 papers were presented in lecture and poster sessions.
TUrbulence modeling encounters mixed evaluation concerning its impor tance. In engineering flow, the Reynolds number is often very high, and the direct numerical simulation (DNS) based on the resolution of all spatial scales in a flow is beyond the capability of a computer available at present and in the foreseeable near future. The spatial scale of energetic parts of a turbulent flow is much larger than the energy dissipative counterpart, and they have large influence on the transport processes of momentum, heat, matters, etc. The primary subject of turbulence modeling is the proper es timate of these transport processes on the basis of a bold approximation to the energy-dissipation one. In the engineering community, the turbulence modeling is highly evaluated as a mathematical tool indispensable for the analysis of real-world turbulent flow. In the physics community, attention is paid to the study of small-scale components of turbulent flow linked with the energy-dissipation process, and much less interest is shown in the foregoing transport processes in real-world flow. This research tendency is closely related to the general belief that universal properties of turbulence can be found in small-scale phenomena. Such a study has really contributed much to the construction of statistical theoretical approaches to turbulence. The estrangement between the physics community and the turbulence modeling is further enhanced by the fact that the latter is founded on a weak theoretical basis, compared with the study of small-scale turbulence.
Fundamentals of Ship Hydrodynamics: Fluid Mechanics, Ship Resistance and Propulsion Lothar Birk, University of New Orleans, USA Bridging the information gap between fluid mechanics and ship hydrodynamics Fundamentals of Ship Hydrodynamics is designed as a textbook for undergraduate education in ship resistance and propulsion. The book provides connections between basic training in calculus and fluid mechanics and the application of hydrodynamics in daily ship design practice. Based on a foundation in fluid mechanics, the origin, use, and limitations of experimental and computational procedures for resistance and propulsion estimates are explained. The book is subdivided into sixty chapters, providing background material for individual lectures. The unabridged treatment of equations and the extensive use of figures and examples enable students to study details at their own pace. Key features: • Covers the range from basic fluid mechanics to applied ship hydrodynamics. • Subdivided into 60 succinct chapters. • In-depth coverage of material enables self-study. • Around 250 figures and tables. Fundamentals of Ship Hydrodynamics is essential reading for students and staff of naval architecture, ocean engineering, and applied physics. The book is also useful for practicing naval architects and engineers who wish to brush up on the basics, prepare for a licensing exam, or expand their knowledge.
This publication documents the proceedings of the first Workshop on Computational Electromagnetics (CEM) and Applications, hosted by the Institute for Computer Applications in Science and Engineering (ICASE) and the NASA Langley Research Center, Hampton, Virginia, 29-31 May, 1996, and attended by approximately 70 people from academia, government laboratories, and industry. ICASE's charter mission in 1972 remains today - to explore novel computer environments (vector in the 1970s; parallel in the 1990s) for scientific computing. These proceedings provide a necessary foundation for symposia in computational electromagnetics for future aerospace applications. The objectives of this CEM Workshop were to provide a forum for many of the leaders of the community to assess the state of CEM technology and to discuss areas of research for future programmatic planning activities. Workshop sessions included topics on optimization, industrial applications, algorithms, and a special panel session was provided during which issues were discussed and future research areas were identified. Hopefully, this publication will stimulate and improve communication among multidisciplinary researchers as well as highlighting several CEM areas that need improvement - especially for highly challenging problems. The two most important criteria in the selection of speakers for the workshop were their substantial contribution to large-scale CEM problems and their ability to articulate the issues confronting the CEM research community. Based on the results obtained, it is anticipated that this publication will be useful to government, industry, and university researchers to plan future research tasks in CEM analytical methods and applications.
Proceedings of the IUTAM Symposium Held in Bochum, Germany, June 28–30 1995
Author: K. Gersten
This volume contains the contributions presented at the IUTAM Symposium on Asymptotic Methods for Turbulent Shear Flows, which was the first international conference on the subject. The book provides an overview of the state of the art in this field and presents results found worldwide. Asymptotic theory is here considered as the application of perturbation methods (singular perturbation methods, multiscale methods, rapid distortion theory etc.) to solving the Reynolds- averaged flow equations for turbulent shear flows at high Reynolds numbers. These methods play an important role in turbulence modelling, as is demonstrated by many examples, including turbulence models describing flow separation. It becomes evident that asymptotic methods enable the extraction of a fairly comprehensive set of results from the governing equations without incorporating a specific turbulence model a priori. Furthermore, these methods can be used to quickly eliminate unsatisfactory models. The book contains valuable results for turbulence researchers, in particular for those working in turbulence modelling.
Proceedings of the Seventh European Turbulence Conference, Held in Saint-Jean Cap Ferrat, France, 30 June-3 July, 1898
Author: Uriel Frisch
Publisher: Springer Science & Business Media
This volume contains an overview of the state of turbulence research with some bias towards work done in Europe. It represents an almost complete collection of the invited and contributed papers delivered at the Seventh European Turbulence Conference, sponsored by EUROMECH and ERCOFTAC and organized by the Observatoire de la Cote d'Azur. High-Reynolds number experiments combined with techniques of imaging, non-intrusive probing, processing and simulation provide high-quality data which put significant constraints on possible theories. For the first time, it has been shown, for a class of passive scalar problems, why dimensional analysis sometimes gives the wrong answers and how anomalous intermittency corrections can be calculated from first principles. The volume is thus geared towards specialists in the area of flow turbulence who could not attend the conference as well as anybody interested in this rapidly-moving field.
Proceedings of the IUTAM Symposium Held in Vienna, Austria, 2–6 June 1997
Author: H.A. Mang
This book contains papers presented at the IUTAM/IACM Symposium `Discretization Methods in Structural Mechanics II' held in Vienna, Austria, in June 1997. During the last decade the broad field of `Discretization Methods in Structural Mechanics' has experienced a remarkable evolution. New aspects have come into focus. Many of them were stimulated by challenging requirements coming from high-tech applications. In these proceedings such recent developments are presented and discussed together with new trends and demands. In view of their relevance, emphasis was put on nonlinear finite element methods and boundary element methods as well as on the coupling of these two numerical methods. Novel developments in other discretization methods having the potential of opening new avenues for promising applications were also considered. The different sources of nonlinearities, such as large deformations, large strains, nonlinear material behaviour (including viscoplasticity, progressive damage, nonlinearities in composites and other microstructured materials), contact with or without friction, etc., require (a) a careful mathematical and mechanical description and modelling, (b) the development of efficient algorithms and (c) a sound computational treatment. Contributions meeting these requirements are presented. Further emphasis was laid on significant improvements concerning efficiency, accuracy and reliability of discretization methods in nonlinear structural mechanics (e.g. error estimation, self-adapting mesh refinement, multigrid methods). A number of papers deal with new aspects of sensitivity analysis and optimization. Neural network strategies as well as modern data processing architectures (such as parallel computers and transputers) and their impact on the developments of new algorithmic concepts are discussed.