Over the past century, a sustained effort has been expended on the research and development of surfaces that reduce the amount of drag experienced by a fluid as it passes by, motivated by both environmental and economic savings. Superhydrophobic surfaces have recently emerged as an attractive means to reduce the levels of skin-friction drag under both laminar and turbulent flow conditions. A superhydrophobic state is attained naturally or synthetically through a combination of surface topology and surface chemistry and can, in some cases, support a free-stress gas-liquid interface. In the presence of bulk fluid motion, the interfaces permit a finite slip velocity which has been credited to the reduction of the average wall shear stress. The fundamental drag reduction mechanism, however, remains unclear. In order to accurately resolve the full spectrum of turbulent scales, direct numerical simulations of fully turbulent channel flow over superhydrophobic textures at a friction Reynolds number of Reτ ≈ 180 were conducted. The instantaneous flow fields were subject to triple decomposition which permits statistical quantities to be accumulated in a phase-averaged form. From these phase-averaged statistics the mean, periodic and stochastic fluid motions can be considered independently. Following a detailed statistical analysis, the contributions of the mean, periodic and stochastic fluid motions towards the local levels of wall shear stress were determined by the derivation and evaluation of an appropriate skin-friction identity. In addition, a new modification to superhydrophobic surfaces is investigated by means of meandering the surface topology in the streamwise direction. Relative to a streamwise-aligned topology, it was anticipated that superior drag reduction would be achieved due to the addition of an oscillatory spanwise motion to the mean flow.

Numerical convection schemes in a time-dependent Computational Fluid Dynamics simulation suffer from numerical diffusion, where a transported scalar quantity experiences a total diffusivity greater than any physical diffusivity due to the viscosity of the surrounding fluid. This work aims to develop and test a novel convection method, combining the Eulerian and Lagrangian frameworks, to eliminate numerical diffusion. A conserved scalar quantity is decomposed into low- and high-frequency components. The low-frequency field is transported in the Eulerian framework using a high-order Central Differencing Scheme, which has a negligible numerical diffusivity and good cost efficiency, but exhibits oscillatory behaviour around sharp changes in gradient. The high-frequency information is described with (computationally expensive) massless Lagrangian particles, where the prescribed particle 'density' provides a balance between accuracy and computational cost. Particles are convected by interpolating the underlying velocity field on to the particle position, while particle diffusion is described using a stochastic Wiener process. After transport an Eulerian representation of the Lagrangian particle field is constructed and added to the low-frequency scalar component, to recover the overall transported field. Formulations of the joint Eulerian-Lagrangian method for Direct Numerical Simulation and Large-Eddy Simulation are proposed. Re-initialisation (particle addition) and particle removal are implemented to maintain accuracy and to reduce the computational cost of the method. The accuracy of the Lagrangian reconstruction is improved through the development and application of localised filtering and deconvolution algorithms. The method is applied in two and three dimensions, where it is effective in removing numerical diffusion, but introduces noise into the scalar field due to the point-like nature of the particles. While the method is at least twice as expensive as traditional Eulerian simulations at the same grid resolution, it is capable of delivering better accuracy and considerably greater cost efficiency than Eulerian simulations at higher resolutions.

This thesis reports an investigation to develop new understanding of pleasant experiences resulting from human-product interaction, which is then used to inform the development of a process and tools to support designers. The key argument of this research is that pleasant experiences can be designed. The thesis starts by providing a foundation of user experience. A new framework of user experience is proposed based on the analysis and synthesis of previous literature (Chapter 1). The interest then shifts from user experience to characterising pleasant experiences. Four empirical studies are presented focusing on aspects such as experiences with great products and the role of positive emotions in those experiences. The first study, investigating how users experience great products, identifies and characterises pragmatic and significant experiences (Chapter 2). Great products were studied as people understood and experienced them. In the second study, a set of twenty-five positive emotions are ranked by users and designers to understand what emotions they prefer to experience and elicit through their designs (Chapter 3). Highly-preferred emotions by users were: satisfaction, inspiration, confidence, joy, amusement and relaxed. Highly-preferred emotions by designers were: curiosity, joy, surprise, confidence, inspiration, fascination, satisfaction, and pride. In the third study, the twenty-five positive emotions are researched to understand their differences in pleasantness and arousal (Chapter 4). Three levels of arousal and pleasantness of emotions were identified and these are: exciting, neutral and calm emotions, and pleasant, quite pleasant, and very pleasant emotions. In the fourth study, anticipation, confidence, inspiration, and sympathy are investigated in depth to create rich profiles of the emotions (Chapter 5). The profiles focus on the triggers, appraisal structures, thought-action tendencies, and thematic appraisals of the emotions. Building on the understanding of pleasant experiences emerged from the re- search above, the thesis then presents evaluative research. In the fifth study, a design process and tools to support designers in the elicitation of pleasant experiences are proposed and tested. The process shows how emotional profiles can be used by designers as a means to create pleasant experiences through emotions (Chapter 6).

Hydrate formation in oil and gas pipelines can be troublesome and often, without a proper remediation, the formation of hydrates can lead to a pipe blockage. As hydrate formation is a non-isothermal process, the modelling of the thermodynamic behaviour of the phases within the flow is proposed. A single energy equation has been formulated and verified with parametric analyses. A new hydrate kinetics routine, based on a two-step hydrate formation mechanism, in an oil-dominated flow is proposed. The first step involves the mass transfer of gas from the free gas phase into the oil (gas dissolution rate) and the second step is the mass transfer of the dissolved gas into the water (gas consumption rate). Suitable models in the form of transport equations for each mechanism, together with appropriate closure relations to account for the agglomeration of hydrate particles and hydrate slurry viscosity, are formulated. Both the energy equation and the hydrate kinetics routine were integrated into an existing in-house research code, TRIOMPH (Transient Implicit One-Dimensional Multiphase). The model was tested and validated against two flow loop experiments, and has shown good agreement. Advancement over the only other existing model in predicting hydrate formation in the heavily slugged hypothetical pipe, has also been shown, giving the current model versatility in simulating both slug and non-slug cases.

Epoxies are a class of high-performance thermosetting polymers which have been widely used in many industrial applications. However, unmodified epoxies are susceptible to brittle fracture due to their highly crosslinked structure. As a result, epoxies are normally toughened to ensure the feasibility of these materials for practical applications. Recently, a new generation of toughening agents such as polysiloxane based core-shell rubber (CSR) particles, amphiphilic block copolymers and silica nanoparticles have been developed to toughen epoxies. These new toughening agents will be studied in this thesis to pursue ultra-tough and stiff epoxies without compromising other desirable properties. Polysiloxane based CSR particles were able to toughen an anhydride cured epoxy over a wide range of temperatures from -109 °C to 20 °C. At -109 °C, the fracture energy of the epoxy could still be increased from 174 to 481 J/m2 with the addition of 20 wt% of the CSR particles. The toughening mechanisms of these CSR particle modified epoxies were identified as shear band yielding and plastic void growth. A series of commercial poly(methyl methacrylate)-b-poly(butylacrylate)-b-poly( methyl methacrylate) (MAM) triblock copolymers were studied as toughening agents in two epoxy systems. The fracture toughness was generally increased by these block copolymers, although their toughening performance was dependent on the crosslink density of the epoxies and the morphologies of the modified epoxies. The MAM modified epoxies were also studied as the matrix materials in fibre-reinforced composites to investigate the transfer of toughness from the matrix materials to the composites. Full (1 to 1) and nearly full toughness transfer was obtained for the composites. Hybrid toughening using a combination of the MAM block copolymer and silica nanoparticles has also been investigated in the same epoxy systems. The addition of the silica nanoparticles further increased the toughness of the MAM modified epoxies if micron-sized MAM particles present.

Delamination has been recognised as the primary defect in composite structures, which can lead to rapid deterioration of the structure. This is because delamination is barely visible damage, and the presence of delamination crack growth between the fibre-matrix layered structure can severely reduce the load bearing capability without being noticed. The present work investigates the matrix toughening approach via the addition of a second phase copolymer and rigid silica nanoparticles in an attempt to enhance the delamination resistance in Glass Fibre (GF) composites. This investigation includes the analysis of the structure/property relationships of toughened epoxy matrices and their corresponding GF composites under quasi-static and fatigue loading conditions. The toughness performance and the toughening mechanisms of the modified epoxies and their corresponding composites are the main theme of this thesis. This investigation revealed a positive correlation between the interlaminar fracture toughness of GF composites and the toughness of the matrix phase. A large toughness increase was observed when using rubber-modified and core-shell rubber (CSR)-modified epoxy matrices. The use of a silica nanoparticle-modified matrix only showed a marginal toughness increase, and in some epoxy systems, the addition of silica nanoparticles was detrimental to the composite toughness. In the hybrid-modified matrix, the largest toughness increase was observed, indicating the presence of a synergistic effect between the rubber particles and silica nanoparticles. The toughening mechanisms in the rubber-modified epoxy were rubber particle cavitation and plastic void growth, whereas in the CSR-modified epoxy the toughening mechanisms were cavitation of the rubbery core and shear deformation in the polymer matrix. In the silica nanoparticle-modified epoxy, debonding of the nanoparticles and subsequent void growth were evident, but the energy dissipation was small and not sufficient to contribute to the large toughness increase. In addition, the silica nanoparticles increased the matrix stiffness and caused the matrix to be less adhered to the fibre surface, thus promoting a fibre-matrix interfacial failure. The fatigue performance of the GF composites with toughened matrices was analysed in terms of fatigue crack growth and fatigue threshold. The addition of rubber particles and silica nanoparticles reduced the fatigue crack growth rate and increased the fatigue threshold values. The fatigue threshold was further increased when using the hybrid-modified matrix suggesting a synergistic toughening effect in the threshold region. Microscopy analysis revealed there were no appreciable difference in the toughening mechanisms between the fatigue and quasi-static fracture behaviour.

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To deliver low carbon buildings requires: a) Performance assessment and option appraisal; b) Industry process to translate selected options into low carbon performance in practice. This thesis aims to make some contribution in each of these two areas. Legislation such as the European Performance of Buildings Directive (EPBD) is stimulating the market to put forward many technical options for design or retrofit of low carbon buildings. The need is identified here for a low cost, EPBD compatible, simulation based, real time method for performance assessment and upgrade option appraisal to inform decisions for a range of users with various levels of technical knowledge. The hypothesis is advanced that such a method can be developed. An EPBD compatible, dynamic simulation based, real time, performance assessment and option appraisal method is then proposed and evaluated. A range of test applications and user groups are considered. Test applications include the generation of energy performance ratings based on a simple questionnaire. Other applications cover a range of individual building, policy or strategy contexts. A critical analysis is carried out of the applicability, scope and limitations of the method. The proposed method proved useful in a range of applications. For other applications some limitations were identified. How these can be addressed is discussed. The development and deployment examples are for a specific building stock but provide insights to enable replication for other situations. The research provides a foundation for further research and development. There is much evidence that selection of appropriate options is not sufficient to achieve low carbon performance. Many issues can lead to gaps between intended and actual performance. Problems are identified in the design and implementation of low carbon systems and controls. Problems include poor understanding, errors in implementation, and poor visibility of actual performance. The need for a method to address these problems is identified. The hypothesis is advanced that such a method can be developed. A Modular Control Mapping and Failure Mode Effect Analysis (FMEA) method is then proposed and evaluated for a range of test applications to buildings intended to be low carbon. The insights from the test applications are reviewed and the scope and limitations of the proposed method discussed. Overall the applications were successful and the useful application demonstrated. The method was deployed post-occupancy, then applicability at various stages of the design process was demonstrated by using concept and detailed design information. The modular control mapping and FMEA process proposed leverages in part the approach taken in industrial sectors identified as benchmarks by proponents of the Building Information Modelling (BIM) initiative. The potential application of further processes from BIM benchmark industry is discussed in the context of current buildings industry initiatives. The performance assessment and option appraisal method, the modular control mapping and FMEA method, and the outcomes from their evaluations are intended to contribute to the realisation of low carbon buildings in practice. The future integration of both methods within a BIM framework is proposed.

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