The research presented here provides a basis for understanding the hydrodynamics of surfboard fin geometries. While there have been select studies on fins there has been little correlation to the shape of the fin and its corresponding hydrodynamic performance. This research analyzes how changing the planform shape of a surfboard fin effects its performance and flow field. This was done by isolating the taper and sweep distribution of a baseline geometry and varying each parameter individually whilst maintaining a constant span and surface area. The baseline surfboard fin was used as a template in Matlab to generate a set of x and y coordinates that defined the outline of the fin shape. These coordinates were then altered by changing either the sweep or taper distribution and resulted in new, unique planform shapes. The new shapes were used to generate 3D models with the NACA 0006 foil as the cross-section hydrofoil. After the geometry was modeled, each fin was meshed and simulated in CFD for incidence angles ranging from 0o to 20o and a fin Reynolds Number of 3.51x105. When the sweep distribution was changed, there was a direct correlation to vortex formation off the leading edge. Increasing the sweep generated a stronger vortex that persisted for higher angles of attack and resulted in higher moments but increased drag. Changing the taper distribution was not as influential. The tapered fin set showed similar flow fields and body forces to each other. Making a fin more rectangular had slight decreases in drag but made the shape more prone to separation.

This work analyzes the solid flow dynamics of gas-solid downer fluidized bed reactor in co-current and, particularly, in counter-current mode. This reactor is potentially interesting for catalytic applications where very short (sub second) and precise contact times are required between the solid catalyst and the gaseous reactants-products. To this aim, a 1.5 m and 36 mm ID downer reactor setup was built to replicate the conditions in a real unit in cold flow and using materials that enable the observation of the solid particle dynamics. Specifically, two state-of-the-art techniques have been used: Particle Image Velocimetry (PIV) and Digital Image Analysis (DIA). Three types of particles have been used: two commercial fluidized catalytic cracking (FCC) particles (ρp = 1300 kg/m3, dp = 75 and 56 μm) and sand (ρp=2600 kg/m3, dp= 370 μm). High-speed cameras were positioned in two axial positions: 70 and 140 cm from the top, to reveal the flow behavior across the reactor. It was found that the solid flow initially was segregated because of the solid feeding design. Thus, 3D printed re-distributer was used to even the solid flow. The solid particles in the counter-current downer was approaching the plug-flow behavior with 23% variation in the velocity gradient across the radial direction, compared with 40% for the co-current counterpart. A method to estimate solid hold-up based on images was developed, yielding values in a good agreement with literature. Keywords: Hydrodynamics, counter-current, downer, PIV, DIA, Solid hold-up

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<p> A study of metal enrichment of the intergalactic medium (IGM) using a series of smooth particle hydrodynamics (SPH) simulations is presented, employing models for metal cooling and the turbulent diffusion of metals and thermal energy. An adiabatic feedback mechanism was adopted where gas cooling was prevented on the timescale of supernova bubble expansion to generate galactic winds without explicit wind particles. The simulations produced a cosmic star formation history (SFH) that is broadly consistent with observations until z ~ 0.5, and a steady universal neutral hydrogen fraction (OHI) that compares reasonably well with observations. The evolution of the mass and metallicities in stars and various gas phases was investigated. At z=O, about 40% of the baryons are in the warm-hot intergalactic medium (WHIM), but most metals (80%-90%) are locked in stars. At higher redshifts the proportion of metals in the IGM is higher due to more efficient loss from galaxies. The results also indicate that IGM metals primarily reside in the WHIM throughout cosmic history, which differs from simulations with hydrodynamically decoupled explicit winds. The metallicity of the WHIM lies between 0.01 and 0.1 solar with a slight decrease at lower redshifts. The metallicity evolution of the gas inside galaxies is broadly consistent with observations, but the diffuse IGM is under-enriched at z ~ 2.5. Metals enhance cooling which allows WHIM gas to cool onto galaxies and increases star formation. Metal diffusion allows winds to mix prior to escape, decreasing the IGM metal content in favour of gas within galactic halos and star forming gas. Diffusion significantly increases the amount of gas with low metallicities and improves the density-metallicity relation. </p> <p> The galactic wind generation mechanism and the wind properties from our simulations were investigated. It was found that: 1. Galactic winds are most efficient for halos in the intermediate mass range 10^10Mo - 10^11 Mo . These winds dominate the metal ejection at all redshifts, although towards lower redshift the contributions from larger halos become relatively more important. At the low mass end gas is prevented from accreting onto halos and has very low metallicities. At the high mass end, the fraction of halo baryons escaped as winds declines along with the decline of stellar mass fraction in these halos. The decrease in wind ejection is likely because of the decreases in star formation activity, wind mass loading and wind escape efficiency as the halo mass increases. 2. The adiabatic feedback can generate winds with mass loading factors comparable to the ones used in explicit superwind models. The mass loading factor decreases towards lower redshift, implying that smaller halos have larger mass loading. 3. Metals located at lower density were generated at earlier epochs from small halos, suggesting that the wind traveling speed can affect the metal distribution in the IGM. </p> / Thesis / Doctor of Philosophy (PhD)

Modeling and simulation tools are described and implemented in a single workflow to develop a means of simulating a ship wake followed by simulated synthetic aperture radar (SAR) and infra-red (IR) images of these ship wakes. A parametric study across several different ocean environments and simulated remote sensing platforms is conducted to generate a preliminary data set that is used for training and testing neural network--based ship wake detection models. Several different model architectures are trained and tested, which are able to provide a high degree of accuracy in classifying whether input SAR images contain a persistent ship wake. Several data fusion models are explored to understand how fusing data from different SAR bands may improve ship wake detection, with some combinations of neural networks and data fusion models achieving perfect or near-perfect performance. Finally, an outline for a future study into multi-physics data fusion across multiple sensor modalities is created and discussed. / Doctor of Philosophy / This dissertation focuses on using computer simulations to first simulate the wakes of ships on the ocean surface, and then simulate airborne or satellite-based synthetic aperture radar (SAR) and infra-red (IR) images of these ship wakes. These images are used to train machine learning models that can be given a SAR or IR image of the ocean and determine whether or not the image contains a ship wake. The testing shows good preliminary results and some models are able to detect ship wakes in simulated SAR images with a high degree of accuracy. Data fusion models are then created which seeks to fuse data sources together in order to improve ship wake detection. These data fusion models are tested using the simulated SAR images, and some of these data fusion models show a positive impact on ship wake detection. Next steps for future research are documented, such as data fusion of SAR and IR data in order to study how fusion of these sensors impacts ship wake detection compared to just a single SAR sensor or multiple SAR sensors fused together.

Many complexities arise when writing software for computational physics. The choice of underlying data structures, physics model representation, and numerical methods used for the solver all add to the overall complexity of a code and significantly affect the simulation speed and accuracy of the solution. This work has integrated multiple recently developed software tools into a unified framework called ELEMENTS. ELEMENTS contains tools to address the complexities of data representation and numerical methods implementation for computational physics applications. ELEMENTS consists of multiple software packages: Elements, MATAR, Swage, Geometry, and SLAM. MATAR is a performance portability and productivity implementation of data-oriented design that leverages KOKKOS for multi-architecture portability. MATAR's data-oriented design allows for highly efficient memory use through the use of contiguous memory allocation and access for optimal performance. The elements library contains the requisite mathematical functions for a wide range of numerical methods and high order field representation, including the Serendipity basis set that allows for a higher-order solution with fewer degrees of freedom than the more standard tensor product elements. Swage is a novel mesh class capable of representing all of the geometric entities required to implement low and high-order continuous and discontinuous Galerkin methods on unstructured hexahedral meshes as well as connectivity structures between the disparate index spaces. SLAM is a library for linear algebra solvers and tools for linking to external solver packages. Combining these tools allows for the research and development of novel methods for solving problems in computational physics. This work discusses the ELEMENTS package and reviews multiple numerical methods built using ELEMENTS.

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The use of shallow fluidized beds for heat exchange has been suggested because they give high bed-to-surface heat transfer rate and require very low bed pressure. However, in comparison with research on deep fluidized beds, only relatively few studies have been devoted to heat transfer in shallow beds, and results from the available literature are often inconsistent. This study represents an integrated research on the hydrodynamics and bed-to-surface heat transfer in shallow beds. The results from this study provide the quantitative basis for the design and efficient operation of shallow fluidized-bed heat-recovery systems. Based upon their physical appearance, shallow fluidized beds have been categorized into nine different types. A "phase diagram" (plot of superficial gas velocity versus static bed height) can be used to delineate the ranges of fluidization variables within which each type of shallow beds will be seen. Pressure-drop data in gas flowing upward through a shallow bed reflect pressure recovery in jets formed immediately above a gas distributor at the bottom of the bed. Pressure-recovery data provide an effective means of distinguishing a shallow bed from a deep one, and suggest that the power consumption across a fluidized bed can be reduced dramatically by dividing a single deep bed into many multi-staged shallow beds. A computerized light probe has been developed for measurements of particle volume-fraction distribution and its statical fluctuation (standard deviation). These data have been shown to quantitatively define: (1) different types of shallow beds; (2) relative magnitude of solid mixing; (3) bed surface and bed height; and (4) jet penetration depth. Based upon observations of the hydrodynamic behavior of shallow fluidized beds, three regions can be identified for heat-transfer applications: a jet-affected region at the bottom, a free-board region at the top, and, sandwiched between theses, a homogeneous region. Only heat-transfer data in the homogeneous region are sufficiently well-behaved to be subjected to quantitative correlation in terms of fluidization variables. For relatively coarse particles (Geldart's Group B particles) the vigor of solid mixing can be the most important factor in affecting the heat-transfer performance. Bed voidage and static electricity effects are found to be important for smaller and/or lighter particles (i.e., Geldart's Group A particles). / Ph. D.

The effect of fin and jet vortex generators on the crossflow separation of a 688 class submarine in a turning maneuver was studied. The vortex generators are located on the top and bottom centerline of the submarine. The intent of the vortex generators is to improve turning performance by changing the hydrodynamic forces incurred from crossflow separation. Performance of the jets and the fins are compared. Oil flow visualization and force and moment measurements were used as the primary diagnostics in determining the effectiveness of various vortex generator configurations. The fins were found to be very effective in delaying cross flow separation, while the jets were less effective. In addition, the oil flows revealed the importance of locating vortex generators near the bow and the critical role the sail plays in the fluid dynamics near the submarine. Overall, the fins were found to be viable as a concept for flow control, while the jets were less attractive. / Master of Science