<p>  </p> <p>In this study, we aimed to explore the potential of integrating wind turbines into tall buildings to harness wind energy in urban areas. Advanced computer simulations will be used to analyze the complex wind patterns and turbulence around tall buildings. We will also study the optimization of wind turbine placement to maximize energy production. We focus on two types of wind turbines, the savonius and a modified savonius, using the Myring formula. We evaluated their performance in turbulent urban areas using computational fluid dynamics simulations. The simulations will also help us understand the wind flow behavior around tall buildings, informing wind turbine placement optimization.</p> <p>Our findings contribute to the understanding of urban wind energy production. This may lead to further advancements in wind turbine design and application in urban environments, promoting sustainable and clean energy production in densely populated areas.</p> <p>We also evaluate the economic feasibility of wind power as an energy source and its potential for commercial applications. Our study's insights are significant for wind energy research, urban planning, and sustainable energy production in cities.</p> <p>To achieve our objectives, we will use state-of-the-art computational tools such as the ANSYS Fluent Student software and the Steady Reynolds Averaged Navier-Stokes (SRANS) K-ε model and K-ω SST models for simulating wind flow around tall buildings.</p> <p>In summary, the goal of this research is to develop a methodology for integrating wind turbines into tall urban buildings to harness wind energy potential. This will contribute to the understanding of urban wind energy production and its economic feasibility for commercial applications.</p>

<p>The mechanical behavior of tissues at the macroscale is tightly coupled to cellular activity at the microscale and tuned by microstructure at the mesoscale. Dermal wound healing is a prominent example of a complex system in which multiscale mechanics regulate restoration of tissue form and function. In cutaneous wound healing, a fibrin matrix is populated by fibroblasts migrating in from a surrounding tissue made mostly out of collagen. Fibroblasts both respond to mechanical cues such as fiber alignment and stiffness as well as exert active stresses needed for wound closure. </p> <p>To model wound healing mechanobiology, we first develop a multiscale model with a two-way coupling between a microscale cell adhesion model and a macroscale tissue mechanics model. Starting from the well-known model of adhesion kinetics proposed by Bell, we extend the formulation to account for nonlinear mechanics of fibrin and collagen and show how this nonlinear response naturally captures stretch-driven mechanosensing. We then embed the new nonlinear adhesion model into a custom finite element implementation of tissue mechanical equilibrium. Strains and stresses at the tissue level are coupled with the solution of the microscale adhesion model at each integration point of the finite element mesh. In addition, solution of the adhesion model is coupled with the active contractile stress of the cell population. The multiscale model successfully captures the mechanical response of biopolymer fibers and gels, contractile stresses generated by fibroblasts, and stress-strain contours observed during wound healing. We anticipate this framework will not only increase our understanding of how mechanical cues guide cellular behavior in cutaneous wound healing, but will also be helpful in the study of mechanobiology, growth, and remodeling in other tissues. </p> <p>Next, we develop another multiscale model with a bidirectional coupling between a microscale cell adhesion model and a mesoscale microstructure mechanics model. By mimicking the generation of fibrous network in experiment, we established a discrete fiber network model to simulate the microstructure of biopolymer gels. We then coupled the cell adhesion model to the discrete model to obtain the solution of microstructure equilibrium. This multiscale model was able to recover the volume loss of fibrous gels and the contraction from cells in the networks observed in experiment. We examined the influence of RVE size, stiffness of single fibers and stretch of the gels. We expect this work will help bridge the activity of cell to the microstructure and then to the tissue mechanics especially in wound healing. We hope this work will provide more rigorous understanding in the study of mechanobiology.</p> <p>At last, we established a computational model to accurately capture the mechanical response of fibrin gels which is a naturally occurring protein network that forms a temporary structure to enable remodeling during wound healing and a common tissue engineering scaffold due to the controllable structural properties. We formulated a strategy to quantify both the macroscale (1–10 mm) stress-strain response and the deformation of the mesoscale (10–1000 microns) network structure during unidirectional tensile tests. Based on the experimental data, we successfully predict the strain fields that were observed experimentally within heterogenous fibrin gels with spatial variations in material properties by developing a hyper-viscoelastic model with non-affined evolution under stretching. This model is also potential to predict the macroscale mechanics and mesoscale network organization of other heterogeneous biological tissues and matrices.</p>

Given the bleak current and projected global climate trends, society is transitioning the energy systems that we rely upon away from fossil fuel based systems to reduce global CO2 emissions. There are now well-established technologies for providing renewable electricity at utility scales, such as wind turbines and solar panels, being deployed at an ever increasing pace. However, solutions for decarbonizing other sectors where fossil fuels are harder to replace are still needed. Current strategies for reducing fossil fuel use in these sectors rely on replacing them with synthetic fuels instead are produced using renewable electricity, and can therefore be part of a net-zero emissions cycle. The focus of this thesis is to examine a novel class of wind energy systems suitable for powering these fuel synthesis processes. Alternative applications of the proposed systems include powering direct air CO2 capture systems to support negative emissions technology efforts. This work develops and presents numerical models for concepts hereafter referred to as mobile offshore wind energy systems (MOWESs). A MOWES is a wind energy system that operates offshore and is not intended to remain stationary during operation. MOWESs would operate far from shore, harnessing a part of the wind resource that would not otherwise be usable. No full- or large-scale MOWES has yet been developed, and there is little work on developing these concepts, even within academia. Steady-state power performance models of two MOWES concepts, namely unmoored floating offshore wind turbines and energy ships, are developed to support further research in this field. Model results suggest that each concept has unique pros and cons and no conclusion can be drawn as to which technology is more effiient overall. A key conclusion of this work is that unmoored floating wind turbines can generate more power by sailing at a constant speed rather than holding station. We also conclude that unmoored floating wind turbines designed for downwind operation can produce as much power as conventional stationary wind turbines given sufficiently high wind speeds. Further work must examine whether the advantages of these technologies are exploitable given realistic wind conditions and when considering the complicated dynamics of the system. / Graduate / 2023-08-09

No description available.

<p>Current industrial practice in the steel Industry involves the use of natural gas with high methane content as a primary energy source. Natural combustion produces greenhouse gases, and with the continued focus on managing and reducing harmful emissions from industrial processes, there is a need for research into alternative sources of energy. Among several alternatives that have been studied is hydrogen: a non-carbon-based fuel. This work uses a coupled computational fluid dynamics (CFD)-finite element analysis (FEA) combustion model to investigate hydrogen utilization as a fuel in a reheat furnace and how it impacts the quality of the steel produced by understanding the three dimensional (3D) flow behavior, furnace temperature profile, thermal stress distribution, heat flux, formation of iron oxides, emission gases and mode of heat transfer onto the steel slabs. The modeling process integrates the five different zones of a pusher type reheating furnace (top and bottom) and modeled using Ansys Fluent 2020R1 and Ansys Workbench 2022R1. Changes in these parameters are determined by comparison to a baseline case that uses methane as fuel and maintaining the same heat input in terms of chemical energy into the furnace. Global mechanism was used for hydrogen and two step mechanism was used for methane combustion. Results revealed a 2.6% increase in average temperature to 1478K across the furnace for hydrogen which resulted in 6.45% increase in maximum heat flux into the slabs. Similar flue gas flow patterns were seen for both cases and heat transfer mode from the combustion gases to the slabs was primarily by radiation (~97%) for both methane and hydrogen. 11.5% increase in iron oxide formation on the slab was recorded for the hydrogen case, however, the bulk of the iron oxide formed was more of wüstites which are the easiest form of iron oxide to descale. However, elevated nitrogen oxide (NOx) levels were recorded for hydrogen combustion which led to further study into NOx mitigation techniques. Application of the staged combustion method using hydrogen fuel showed potentials for NOx reduction. The use of regenerative burners further conserved exergy losses in hydrogen fuel application. Insignificant deviation from base case thermal stress distribution and zero carbon emission from the hydrogen case indicates the usability of hydrogen as an alternative fuel in reheating furnace operations. </p>

Modelling wastewater temperature variations in a network of 3048 sewer pipes was achieved in this project. Recovering heat from sewers presents attractive options for producing clean energy. However, heat recovery from sewerage may result in wastewater temperature drops which may reduce the influent temperature at the wastewater treatment plant (WWTP). This drop in the WWTP influent temperature may result in the degradation of the biological treatment stage. Therefore, it is vital to predict the impact of recovering heat from sewers on the wastewater temperature. Sewer temperatures along with hydraulic data were measured for up to a year in four different Belgian sites. The measured data was utilised to calibrate a deterministic sewer pipe model that estimates the wastewater temperature variation along the sewer pipe profiles. The latter model was calibrated using data from two sites and then validated using independent data from the other two sites. The sewer pipe model was then further developed to model wastewater temperature variations in a large (3048 pipe) network. The large network model was tested by implementing three different heat recovery scenarios. It was observed that 9 MW may be recovered from the 3048 pipe network, serving a catchment with a population equivalent of 79500 inhabitants, without impacting negatively on the biological processes. / INNERS project funded by EU Interreg IVB

Energy use in buildings account for 32% of total global final energy consumption, and consequently, a large portion of energy - related greenhouse gas emissions. Passive Solar Designs are sustainable building techniques that use solar energy to heat or coo l living spaces without the aid of mechanical or electrical devices. This paper aims to evaluate the effectiveness of Passive Solar Housing as a possible solution to the heating challenges currently faced in Ladakh, India, from the environmental, social, and economic sustainability perspectives. Two types of Passive Solar Techniques are studied: Trombe Walls and Direct Gain. This is to be achieved by a dualistic approach, combining quantitative and qualitative data to gain a holistic view of the situation. Quantitative data were collected from rooms built with the two different approaches. This information was used to determine the energy efficiency of each Passive Solar Design, and as a basis for building a numerical model that simulates the behaviour of Trombe Walls in conditions not observed during the data collection. Qualitative data were obtained through interviews with the residents of Passive Solar Houses in the villages of Palam and Khardong. The results show that Trombe Walls are significantly more effective at keeping a stable temperature than the Direct Gain technology. The interview responses verify and validate these findings whilst describing many positive effects of living in houses with Trombe Walls. Using the numerical model, it becomes apparent that increasing room size reduces the effectiveness of the Trombe Wall room. In conclusion, Passive Solar Housing can be, both from a social and economic perspective, a very effective method to maintain comfortable living conditions while reducing the environmental impact compared to traditional construction methods. / 32% av den globala energikonsumtionen kommer från energianvändning i byggnader. Det innebär att en betydande andel utsläpp av växthusgaser kommer från dem. Passivhus är en samling hållbara byggtekniker som använder solens energi för att värma upp eller kyla ner en levnadsyta utan att förlita sig på mekaniska eller elektriska medel. Denna studie ämnar utvärdera lämpligheten av Passivhus som en lösning på de uppvärmningsutmaningar som Ladakh, Indien ställs inför, vilket görs ur de miljömässiga, sociala, och ekonomiska hållbarhetsperspektiven. Två typer av Passivhus undersöks: Trombeväggar och Direct Gain. Metoden innefattar en kvantitativ och en kvalitativ datainsamling för att ge en heltäckande bild av situationen. Kvantitativa data insamlades i rum byggda med de två olika teknikerna – denna data användes sedan i en numerisk modell som simulerar hur en Trombevägg beter sig under omständigheter som inte direkt observerats inom ramen för denna studie. Kvalitativa data erhölls från intervjuer med invånarna av Passivhus i de två byarna Palam och Khardong. Resultaten påvisar att Trombeväggar är märkbart mer effektiva på att hålla en stabil inomhustemperatur jämfört med Direct Gain. Intervjusvaren verifierar och validerar resultaten samtidigt som de beskriver flertalet positiva följder av att bo i ett Passivhus. Genom att använda den numeriska modellen blir det tydligt att en ökning av storleken på rummen minskar Trombevägg - rummens förmåga att bibehålla en adekvat inomhustemperatur. Sammanfattningsvis kan Passivhus, från sociala och ekonomiska perspektiven, vara en mycket effektiv metod för att säkerställa tillfredställande levnadsvillkor, samtidigt som de har en mindre negativ påverkan på miljön än traditionella byggnadsmetoder.

<p>The rapid growth of fields such as metamaterials, composites, architected materials, porous solids, and micro/nano materials, along with the continuing advancements in design and fabrication procedures have led to the synthesis of complex structures having intricate material distributions and non-trivial geometries. These materials find important applications including biomedical implants and devices, aerospace and naval structures, and micro/nano-electromechanical devices. Theoretical and experimental evidences have shown that these structures exhibit size-dependent (or, nonlocal) effects. This implies that the response of a point within the solid is affected by a collection of points; ultimately a manifestation of the multiscale deformation process. Broadly speaking, at a continuum level, the mathematical description of these multiscale phenomena leads to integral constitutive models, that account for the long-range interactions via nonlocal kernels. </p> <p><br></p> <p>Despite receiving considerable attention, the existing class of approaches to nonlocal elasticity are predominantly phenomenological in nature, following from their definition of the material parameters of the nonlocal kernel based on 'representative volume element' (RVE)-based statistical homogenization of the heterogeneous microstructure. The size of the RVE required for practical simulation, does not achieve a full-resolution of the intricate heterogeneous microstructure, and also implicitly enforces the use of symmetric nonlocal kernels to achieve thermodynamic consistency and mathematically well-posedness. The latter restriction directly limits the application of existing approaches only to the linear deformation analysis of either periodic or isotropic nonlocal structures. Additionally, the lack of a consistent characterization of the nonlocal effects, often results in inconsistent (also labeled as 'paradoxical') predictions depending on the nature of the external loading. In order to address these fundamental theoretical gaps, this dissertation develops a fractional-order kinematic approach to nonlocal elasticity by leveraging cutting-edge mathematical operators derived from the field of fractional calculus.</p> <p><br></p> <p>In contrast to the class of existing class of approaches that adopt an integral stress-strain constitutive relation derived from the equilibrium of the RVE, the fractional-order approach is predicated on a differ-integral (fractional-order) strain-displacement relation. The latter relation is derived from a fractional-order deformation-gradient mapping between deformed and undeformed configurations, and this approach naturally localizes and captures the effect of nonlocality at the root of the deformation phenomena. The most remarkable consequence of this reformulation consists in its ability to achieve thermodynamic and mathematical consistency, irrespective of the nature of the nonlocal kernel. The convex and positive-definite nature of the formulation enabled the use of variational principles to formulate well-posed governing equations, the incorporation of nonlinear effects, and enabled the development of accurate finite element simulation methods. The aforementioned features, when combined with a variable-order extension of the fractional-order continuum theory, enabled the physically consistent application of the nonlocal formulation to general continua exhibiting asymmetric interactions; ultimately a manifestation of material heterogeneity. Indeed, a rigorous theoretical analysis was conducted to demonstrate the natural ability of the variable-order in capturing the role of microstructure in the deformation of heterogeneous porous solids. These advantages allowed the application of the fractional-order kinematic approach to accurately and efficiently model the response of porous beams and plates, with random microstructural descriptions. Results derived from multiphysical loading conditions, as well as nonlinear deformation regimes, are used to demonstrate the causal relation between the kinematics-based fractional-order characterization of nonlocal effects and the natural role of microstructure in determining the macroscopic response of heterogeneous solids. The potential implications of the developed formalism on scientific discovery of material laws are examined in-depth, and different areas for further research are identified.</p>

<p>Recreational beaches of the Great Lakes play a critical role in the quality of life for beach goers and contribute to the economic and environmental health of the Great Lakes region. Over the past decade, concerned local residents, municipalities, and public beach goers have observed the deteriorating beach quality along the shores of the Great Lakes. Numerous problems exist at these beaches including: high levels of <em>E.coli</em>, encroachment of invasive and non-native vegetation, iron staining, loss of sand. However, the more pervasive problem appears to be increased wet conditions at beaches that use to be dry. This study was undertaken to investigate the physical and hydrological factors that control wet and dry beaches, in order to determine why these beaches exist. Combined field, laboratory, and modelling methodologies were used to characterize four beach sites and calibrate beach models along southern Georgian Bay in Tiny Township, ON. The results of this research indicate that there are three interconnected factors that influence wet and dry beaches, including: (1) texture of a beach, (2) depth to the water table, and (3) elevation of the ground surface. Texture is the primary factor that controls the moisture conditions at a beach even though all beaches were classified as sands. This is a consequence of the fact that fine grained sands have significantly higher capillary rise and retain higher moisture contents above the water table compared to coarse grained sands. Depth to the water table influences the moisture conditions at a beach through its association with the relative position of the top of the capillary rise within respect to the surface of the beach. Ground surface elevation influences the depth of sand above the water table at a beach; lower and flatter surface elevations have the water table (and capillary rise) closer to the beach surface than at beaches with steeper elevations. In summary, wet beaches have high moisture contents at and near the surface of a beach (> 10 %), shallow water tables (~ < 50 cm), and flat ground surface elevations. Dry beaches have low moisture contents at and near the surface of a beach (< 10 %), deep water tables (~ > 50 cm), and steep ground surface elevations. Using the numerical model HYDRUS-2D, four calibrated beach models provide a framework for beach managers to gain insights into beach quality issues through scenario testing. Beaches with shallow water tables and flat surface elevations (either natural or human-induced) are at greater risk of becoming wet under high lake level scenarios than beaches with steeper surfaces (dry beaches). Heavy precipitation events are temporary and do not convert dry beaches into wet beaches and high evaporation rates do not convert wet beaches into dry beaches; conversion of beaches is mainly influenced by beach surface alterations (e.g. bulldozing and removing sand dunes). The conclusion of this study is that hydrological factors are primary controls on the quality of the beaches and the associated problems along the shores of the Great Lakes.</p> / Master of Science (MSc)

The effect of using high voltage DC and AC on the heat transfer process during the melting of a Phase Change Material (PCM) in a rectangular enclosure was studied experimentally and numerically. The experiments were conducted for two configurations: (a) a horizontal rectangular enclosure in which the initial melting process is governed by heat conduction, (b) a vertical rectangular enclosure in which the initial melting process is governed by heat convection. The level of heat transfer enhancement was quantified by using a novel experimental facility for the horizontal configuration. The experimental methodology was verified first against non-EHD melting cases and then was further expanded to include the EHD effects. The experiments showed that EHD forces can be used to enhance a conduction dominated melting up to a maximum of 8.6-fold locally and that the level of enhancement is directly related to the magnitude of the applied voltage. It was found that the main mechanism of enhancement in these cases can be attributed to the electrophoretic forces and that the role of the dielectrophoretic forces is minimal under the applied voltages. In the vertical configuration, the effect of the magnitude of the applied voltage, the applied voltage wave-form, the gravitational Rayleigh number, Stefan number and the aspect ratio of the enclosure on the heat transfer enhancement were investigated experimentally. A novel shadowgraph experimental measurement system was developed and verified against the analytical correlations of natural convection in rectangular enclosures and the non-EHD melting performance was verified against the bench mark experiments of Ho (1984). The shadowgraph system was used to measure the local heat transfer coefficient across the heat source wall (the heat exchanger surface). The local heat transfer measurements along with the melting temporal profiles were used to explain and visualize the coupling between the Electrohydrodynamics (EHD) forces and the gravitational forces. It was found that the EHD forces could still enhance the melting process even for an initially convection dominated melting process. The mechanism of enhancement was found to be a bifurcation of the initial convection cell into multiple electro-convective cells between the rows of the electrodes. The shadowgraph system was used to assess the interaction between the electrical and the gravitational forces through the visualization of these cells and quantifying their size. The EHD heat transfer enhancement factor was found to increase by the increase of the applied voltage, reaching a 1.7 fold enhancement at the lower gravitational Rayleigh number tested and 1.45 fold for the highest gravitational Rayleigh and Stefan number. The effect of the polarity of the applied voltage was tested for the different cases and it was found that there was no significant difference between the positive and the negative polarities when the magnitude of the applied voltage was below 4 kV. At higher voltages- 6kV- the negative polarities showed better level of enhancement when compared to the positive applied voltage. It was again found that the main mechanism of enhancement is attributed to charge injection from the high voltage electrodes. A scaling analysis was conducted based on the previous conclusions and the dominant mechanism of enhancement to describe the problem in non-dimensional form. An electrical Rayleigh number was introduced and its magnitude was correlated to the magnitude of the injected current. The melt volume fraction was then represented against the non-dimensional parameter (n+1)(H/W)Fo.Ste.RaE^0.25 and the melt fraction temporal profiles for the different voltages collapsed well against this parameter. Finally, a numerical analysis was conducted on the role of the dielectrophoretic forces during the melting of Octadecane and when they would become of significant importance. The results of the numerical model supported the experimental findings and suggested that a minimum of 15 kV is needed in order to realize the effect of the dielectrophoretic forces. The numerical model was used to understand the interaction between the gravitational and the dielectrophoretic forces at different ranges of both gravitational Rayleigh number and electrical Rayleigh number. The model was complemented with scaling analysis to determine the governing scales of the problem and the dielectrophoretic Rayleigh number was deduced from the study. / Thesis / Doctor of Philosophy (PhD)