Engineering Commons^™

Improving Quantification Of Mitral Regurgitation Through Computational Fluid Dynamics And Ex Vivo Testing, Alexandra Flowers

Electronic Theses and Dissertations

Mitral regurgitation (MR) is a prominent cardiac disease affecting more than two million people in the United States alone. In order for patients to receive proper therapy, regurgitant volume must first be quantified. As there are an array of methods to do so, the proximal isovelocity surface area (PISA) method continues to be the most accurate and clinically used method. However, there are some difficulties obtaining the necessary measurements need for this when performing transthoracic echocardiography. This study aims to evaluate and present techniques that may be used to more accurately quantify regurgitation through ex vivo testing and computational fluid …

A Study Of Several Applications Of Parallel Computing In The Sciences Using Petsc, Nicholas Stegmeier

Electronic Theses and Dissertations

The importance of computing in the natural sciences continues to grow as scientists strive to analyze complex phenomena. The dynamics of turbulence, astrophysics simulations, and climate change are just a few examples where computing is critical. These problems are computationally intractable on all computing platforms except supercomputers, necessitating the continued development of efficient algorithms and methodologies in parallel computing. This thesis investigates the use of parallel computing and mathematical modeling in the natural sciences through several applications, namely computational fluid dynamics for impinging jets in mechanical engineering, simulation of biofilms in an aqueous environment in mathematical biology, and the solution …

Dosi In Novel Geometry Dishes, Jonathan Lawrence Lambert Jones

Electronic Theses and Dissertations

Effects of hemodynamic forces on cellular response are well studied. Wall shear stress is regularly accepted as the primary hemodynamic force affecting cellular response. Hemodynamic forces studies utilize Petri dishes on orbital shakers to grow cells for the experiments since this is an easily scalable system. However, characterizing the hemodynamics is difficult since the oscillatory swirling motion creates multidirectional and variable magnitude shear throughout the dish. Thus, a novel geometry dish that could create uniaxial shear with less variation in magnitude would be advantageous for studying shear stress effects on cellular response. The purpose of this thesis was to explore …

Cfd Modeling Of Entrance And Exit Geometries Of A Wind Speed Accelerator., David Russ

Electronic Theses and Dissertations

Current wind power technology is not economically feasible throughout most of the United States due to low average wind speeds. A design for a small-scale wind concentrator device suitable for use in areas of low wind velocity was tested using computational fluid dynamics (CFD). Using a novel approach, the device seeks to accelerate incoming air above minimum velocities required for economical power generation. The novel approach employs a funnel shaped inlet with relief vents along the circumference, so as to alleviate backpressure. Both inlet and outlet sections utilize funnel shapes with both parabolic and hyperbolic regions. All geometry and mesh …

Purge And Secondary Flow Interaction Control By Means Of Platform Circumferential Contouring, Melissa Harris

Electronic Theses and Dissertations

This study presents an attempt to reduce the losses produced by the purge flow in a turbine stage by incorporating circumferential platform contouring. Two contours are proposed and compared against a baseline at different levels of swirl. The computational simulations were performed using a RANS three-dimensional Computational Fluid Dynamics code with the Shear Stress Transport turbulence model. The results of steady simulations demonstrate that for the first contour, when the flow is swirled to 50% of the rim speed, the purge flow exits the cavity with less cross flow. This in turn reduces the strength of the passage vortex. However, …

Heat Transfer In A Coupled Impingement-Effusion Cooling System, Mark W. Miller

Electronic Theses and Dissertations

Gas turbine engines are prevalent in the today’s aviation and power generation industries. The majority of commercial aircraft use a turbofan gas turbine engines. Gas turbines used for power generation can achieve thermodynamic efficiencies as high as 60% when coupled with a steam turbine as part of a combined cycle. The success of gas turbines is a direct result of a half century’s development of the technology necessary to create such efficient, powerful, and reliable machines. One key area of technical advancement is the turbine cooling system. In short, increasing the turbine inlet temperature leads to a rise in cycle …

Computational Fluid Dynamic Optimization And Design For The Airborne Laser System, Matthew James Opgenorth

Electronic Theses and Dissertations

The Airborne Laser (ABL) was designed to destroy any ballistic missile shortly after launch that could be a threat to the United States and its allies. The ABL uses several lasers to accomplish the destruction of the ballistic missile, most notably the high powered Chemical Oxygen Iodine Laser (COIL). The COIL is a complex device that could be improved upon in several areas that will result in overall weight reduction, refinement of beam quality, and increased magazine capacity.

This dissertation presents novel design and optimization techniques coupled with fluid dynamics to improve the performance of the COIL system. The focus …

Developing Dns Tools To Study Channel Flow Over Realistic Plaque Morphology, Ryan M. Beaumont

Electronic Theses and Dissertations

In a normal coronary artery, the flow is laminar and the velocity is parabolic in nature. Over time, plaques deposit along the artery wall, narrowing the artery and creating an obstruction, a stenosis. As the stenosis grows, the characteristics of the flow change and transition occurs, resulting in turbulent flow distal to the stenosis. To date, direct numerical simulation (DNS) of turbulent flow has been performed in a number of studies to understand how stenosis modifies flow dynamics. However, the effect of the actual shape and size of the obstruction has been disregarded in these DNS studies. An ideal approach …

Viscoelastic Roll Coating Flows, Mitchell A. Johnson

Electronic Theses and Dissertations

The physics of a fluid flow between two rotating cylinders is important in processes such as bearing lubrication, roll coating, and printing. A small amount of dissolved polymer in the fluid can have a large impact on the behavior of the process. Viscoelasticity affects the stability of application and metering processes, and reduces the maximum speed at which a uniform film can be coated onto a substrate. The goal of this work is to characterize the effect of viscoelasticity on the forward roll coating operation. A bench-top apparatus simulated the process. Measurements of the gap between the roll surfaces, pressure …