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This thesis focuses on the numerical simulation of yacht sails using both computational fluid dynamics (CFD) and fluid structure interaction (FSI) modelling. The modelling of yacht sails using RANS based CFD and the SST turbulence model is justified with validation against wind tunnel studies (Collie, 2005; Wilkinson, 1983). The CFD method is found to perform well, with the ability to predict flow separation, velocity and pressure profiles satisfactorily. This work is extended to look into multiple sail interaction and the impact of the mast upon performance. A FSI solution is proposed next, coupling viscous RANS based CFD and a structural code capable of modelling anistropic laminate sails (RELAX, 2009). The aim of this FSI solution is to offer the ability to investigate sails' performance and flying shapes more accurately than with current methods. The FSI solution is validated with the comparison to flying shapes of offwind sails from a bespoke wind tunnel experiment carried out at the University of Nottingham. The method predicted offwind flying shapes to a greater level of accuracy than previous methods. Finally the CFD and FSI solution described here above is showcased and used to model a full scale Volvo Open 70 racing yacht, including multiple offwind laminate sails, mast, hull, deck and twisted wind profile. The model is used to demonstrate the potential of viscous CFD and FSI to predict performance and aid in the design of high performance sails and yachts. The method predicted flying shapes and performance through a range of realistic sail trims providing valuable data for crews, naval architects and sail designers.

This thesis addresses the formulation and assessment of the damage survivability of passenger/RO-RO vessels from a fundamental point of view, whilst accounting for water ingress and taking fully into consideration vessel and flood water dynamics. Following the mathematical formulation, a numerical code was developed in the time domain capable of predicting the dynamic behaviour of the damaged vessel in a realistic environment. The developed model describes a free drifting vessel undergoing extreme motions in six degrees-of-freedom under the action of wind, current and waves of arbitrary direction whilst subjected to progressive flooding. The position and attitude of the vessel are updated continuously in time and consequently all the terms in the vessel/flood water systems. A semi-analytical method is also presented, for the evaluation of the flooding rate as a function of the relative position of the water level on either side of a damage opening. This treatise begins w ith a thorough review of the available literature concerning models and methods proposed to date to assess damaged stability and survivability of passenger ships aiming to identify the strength and weaknesses of the existing theories and determine the key factors involved in the degradation of a vessel's ability to survive damage. Having validated the numerical code to the extent that confidence was gained of its ability to simulate the dynamic behaviour of the damaged vessel meaningfully and to predict her resistance to capsize with acceptable accuracy, a topdown approach was pursued, leading from a comprehensive model - including most of the critical features highlighted by the preliminary investigation - to a simplified one in which only the most relevant elements are retained if the significance of which had been demonstrated through a sensitivity analysis designed for this purpose, thus aiding in the transition of complex models to becoming useful engineering "tools". The mathematical/numerical models described in this thesis represent the most advanced treatment to date of the ability of a damaged vessel to resist capsize in a seaway. The most surprising conclusion of the investigation presented herein is that the damage survivability of a passenger/RO-RO ships can be predicted with sufficient engineering accuracy with the simplest of models, deriving from the fact that at the final stages before capsize, the "fate" of the vessel is governed by quasi-static forces.

Deep-ocean (benthic) landers are free-falling vehicles that are deployed from a ship and descend to the ocean floor by virtue of attached ballast. They carry with them scientific instrumentation to carry out in-situ experiments, and once operation is complete, an acoustic command from the surface vessel causes the lander to release its ballast and allow buoyancy to return it to the surface for recovery. Landers function autonomously, typically under the control of a central micro-controller and data-logger. The extreme environment in which landers operate require that all electronics is contained in special pressure housings and interconnection between modules is made using expensive deep-ocean cables and connectors. This thesis presents the concept of a new Controller Area Network (CAN)-based architecture, and a report is given of the development of a miniature network interface board suitable for use on benthic landers. One application of lander technology is in tracking the movements of abyssal fishes that forage close above the ocean floor. Small acoustic transponders are wrapped in bait and attached to the ballast of the lander. Scavenging fish attracted to the bait consume the transponders, after which a sonar system on the vehicle can track their movements. A new method for tracking these fishes is presented that uses a short-baseline hydrophone array mounted on a specially designed lander, AUDOS II. With no moving parts, this method has many advantages over previous systems that relied on scanning directional sonar. Tracking resolution has been greatly improved, and new software tools allow the movements of tracked fish to be viewed quickly and with ease.

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This thesis describes an analytical and experimental study to determine the mechanical characteristics of the pump mounting, bell housing type. For numerical purposes, the mount was modelled as a thin circular cylindrical shell with cutouts, stiffened with rings and stringers; the boundary conditions were considered to be either clamped-free or clamped-supporting rigid heavy mass. The theoretical study was concerned with both the static response and the free vibration characteristics of the mount. The approach was based on the Rayleigh-Ritz approximation technique using beam characteristic (axial) and trigonometric (Circumferential) functions in the displacement series, Love - Timoshenko thin shell theory. determine the effect of the supported in association with the Studies were carried out to heavy mass on the static response, frequencies and mode shapes; in addition, the effects of stringers, rings and cutouts on vibration characteristics were investigated. The static and dynamic formulations were both implemented on the Hewlett Packard 9845 computer. The experimental study was conducted to evaluate the results of the natural frequencies and mode shapes, predicted numerically. In the experimental part, a digital computer was used as an experiment controller, which allowed accurate and quick results. The following observations were made: 1. Good agreements were obtained with the results of other investigators. 2. Satisfactory agreement was achieved between the theoretical and experimental results. 3. Rings coupled the axial modal functions of the plain cylinder and tended to increase frequencies, except for the torsion modes where frequencies were reduced. Stringers coupled the circumferential modal functions and tended to decrease frequencies. The effect of rings was stronger than that of stringers. 4. Cutouts tended to reduce frequencies; in general, but this depends on the location of the cutouts; if they are near the free edge then an increase in frequencies is obtained. Cutouts coupled both axial and circumferential modal functions. 5. The supported heavy mass had similar effects to those of the rings, but in an exaggerated manner, particularly in the reduction of torsion frequencies. 6. The method of analysis was found to be a convenient analytical tool for estimating the overall behaviour of the s6ell with cutouts. Proposals are offered regarding further relating work. Key words: Pump mounting ~ Shells 1 Rayleigh-Ritz ~ C.A.D.

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No description available.

A comparison of a high speed container ship using a rudder versus a podded propulsor is made to study replacing a rudder with a pod. A mathematical model is altered to simulate a ship operating with a rudder and with a pod to maneuver. The model incorporates the nonlinear maneuvering equations and couples the surge and sway forces, yaw and roll moment, and the roll angle induced during a steady turn with varying rudder and pod angles. The model uses the hydrodynamic derivatives and coefficients for a high speed container ship. The equations are numerically integrated in order to predict the roll angle, sway and surge velocities, and the ship's position in the xy-plane. Both transient and steady state results are utilized to quantify the relative efficiency of each system. The results are used as a preliminary study into replacing a rudder on a ship with a podded propulsor. The results indicate that the ship responds faster and has a shorter turning radius with the pod at lower initial speeds and pod angles, while the rudder responds better at high speeds regardless of angle. Further research is necessary to study the effects of changing the pod's position and increasing the number of pods used. / US Navy (USN) author.