Calculation of Three-dimensional Boundary Layers on Ship Forms


Book Description

An implicit finite difference technique, in curvilin ear-orthogonal surface coordinates, has been developed for the solution of the differential equations of three-dimensional laminar and turbulent boundary layers on ship forms. For turbulent flow, a two-layer eddy-viscosity model has been employed as the closure model. The initial and boundary conditions required to solve the equations and the stability and accuracy of the numerical method are discussed at some length. Two mathematically-defined simple three-dimensional ship forms are studied in some detail. These are a tri-axial ellipsoid and a double elliptic ship.




Calculation of Three-dimensional Boundary Layers on Bodies at Incidence


Book Description

Three-dimensional thin boundary-layer equations for laminar and turbulent flows are solved by two different numerical schemes. The methods are applied to the flow over bodies of revolution at incidence and the results are compared with the available experimental data in order to study the range of validity of the classical boundary-layer approximations in regions of increasing circumferential gradients and flow reversal associated with the early stages of a free-vortex type of separation. Comparison with the DFVLR 6:1 spheroid data of Meier et al and the 4:1 combination-body data of Ramaprian, Patel and Choi indicate that the methods perform well in regions where the boundary layer remains thin but the predictions deteriorate as the boundary layer thickens. The results point out the need for the development of methods of handle thick boundary layers and viscous-inviscid interactions. (Author).




Calculations of Three-dimensional Turbulent Boundary Layers Using the Crank-Nicolson Method


Book Description

This report describes the results of the three-dimensional turbulent boundary-layer calculations performed for the Eurovisc Workshop held in Berlin on 1 April 1982. It is shown that the present method, based on the Crank-Nicolson finite-difference scheme and a simple eddy-viscosity model for turbulence, yields satisfactory results provided regions of viscous-inviscid interaction, which were present in at least three of the four test cases, are avoided. (Author).




Flow-visualization of Three-dimensional Boundary-layer Separation on Bodies of Revolution at Incidence


Book Description

Surface streamline patterns on three bodies of revolution, namely a spheroid, a low-drag body and a hemisphere-hemispheroid combination body, have been examined at several angles of attack. Most of the tests were performed at low Reynolds numbers in a hydraulic flume using colored dye to make the surface flow visible. A limited number of experiments was also carried out in a wind tunnel, using wool tufts, to study the influence of Reynolds number and turbulent separation. The study has verified some of the important qualitative features of three-dimensional separation criteria proposed earlier by Maskell, Lighthill, Wang and others. The observed locations of laminar separation lines on a spheroid at various incidences have been compared with the numerical boundary-layer solutions of Wang, and it is suggested that the quantitative differences may be attributed to the significant viscous-inviscid interaction, especially at large incidences. (Author).







Practical Design of Ships and Other Floating Structures


Book Description

This proceedings contains the papers presented at The 8th International Symposium on Practical Design of Ships and Other Floating Structures held in China in September 2001 - the first PRADS of the 21st Century. The overall aim of PRADS symposia is to advance the design of ships and other floating structures as a professional discipline and science by exchanging knowledge and promoting discussion of relevant topics in the fields of naval architecture and marine and offshore engineering. In line with the aim, in welcoming the new era, this Symposium is intended to increase international co-operation and give a momentum for the new development of design and production technology of ships and other floating structures for efficiency, economy, safety, and environmental production. The main themes of this Symposium are Design Synthesis, Production, Hydrodynamics, Structures and Materials of Ships and Floating Systems. Proposals for over 270 papers from 26 countries and regions within the themes were received for PRADS 2001, and about 170 papers were accepted for presentation at the symposium. With the high quality of the proposed papers the Local Organising Committee had a difficult task to make a balanced selection and to control the total number of papers for fitting into the allocated time schedule approved by the Standing Committee of PRADS. Volume I covers design synthesis, production and part of hydrodynamics. Volume II contains the rest of hydrodynamics, and structures and materials.




Scientific Bulletin


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Naval Hydrodynamics


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Proceedings


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Marine Simulation and Ship Manoeuvrability


Book Description

Real-time, interactive ship simulators limped onto the scene, in the wake of flight simulators, some years ago. The maritime industries have a long history of conservatism, but this is now changing rapidly. The information age has also swept over ships and shipping, and has been taken to heart to such an extent that, for example, flight simulators now cooperate with ship simulators and import useful new concepts and methodologies. The more than 50 papers contained in this book show what and why. Although traditionally conservative, the marine world is also traditionally international and this has not changed. The papers in the book are by leading authors from all over the world and provide a detailed snap-shot of the rapidly advancing state-of-the-art, together with pointers to the future. The overall theme of MARSIM '96 and therefore also of this book is: Vessel manouevrability and marine simulation research, training and assessment, and includes original papers on topics such as bridge resource management, distant learning and simulators coupled via The Internet, virtual reality, neural networks, rudder-propeller hydrodynamics, prime mover models, squat in shallow water, and many more.