Engineering Commons^™

A Numerical Study Of Droplet Formation And Behavior Using Interface Tracking Methods, Sandeep Menon

Open Access Dissertations

An adaptive remeshing algorithm has been developed for multiphase flow simulations using the moving-mesh interface tracking (MMIT) technique. The edge-swapping algorithm uses the Delaunay criterion (in 2D) and a dynamic programming technique (in 3D) to maximize the quality of mesh primitives surrounding edges in the mesh, and performs local remeshing to minimize interpolation errors. Edge bisection and contraction operations are also performed to adjust the mesh resolution around important features like fluid-interfaces, driven by a local length scale estimation algorithm that is efficient and easily parallelized. Flow-field interpolation after reconnection is achieved using a conservative, second-order accurate remapping scheme that …

Engineering Modeling, Analysis And Optimal Design Of Custom Foot Orthotic, Lieselle Enid Trinidad

Open Access Dissertations

This research details a procedure for the systematic design of custom foot orthotics based on simulation models and their validation through experimental and clinical studies. These models may ultimately be able to replace the use of empirical tables for designing custom foot orthotics and enable optimal design thicknesses based on the body weight and activities of end-users. Similarly, they may facilitate effortless simulation of various orthotic and loading conditions, changes in material properties, and foot deformities by simply altering model parameters. Finally, these models and the corresponding results may also form the basis for subsequent design of a new generation …

The Parameter Signature Isolation Method And Applications, James Richard Mccusker

Open Access Dissertations

The aim of this research was to develop a method of system identification that would draw inspiration from the approach taken by human experts for simulation model tuning and validation. Human experts are able to utilize their natural pattern recognition ability to identify the various shape attributes, or signatures, of a time series from simulation model outputs. They can also intelligently and effectively perform tasks ranging from system identification to model validation. However, the feature extraction approach employed by them cannot be readily automated due to the difficulty in measuring shape attributes. In order to bridge the gap between the …

Modeling Of Flash Boiling Flows In Injectors With Gasoline-Ethanol Fuel Blends, Kshitij Deepak Neroorkar

Open Access Dissertations

Flash boiling may be defined as the finite-rate mechanism that governs phase change in a high temperature liquid that is depressurized below its vapor pressure. This is a transient and complicated phenomenon which has applications in many industries. The main focus of the current work is on modeling flash boiling in injectors used in engines operating on the principle of gasoline direct injection (GDI). These engines are prone to flash boiling due to the transfer of thermal energy to the fuel, combined with the sub-atmospheric pressures present in the cylinder during injection. Unlike cavitation, there is little tendency for the …

A Computational Simulation Of Supercritical Carbon Dioxide And Ethanol Capillary Flow, Thomas W. Furlong

Masters Theses 1911 - February 2014

Homogenous and separated flow methods have been presented for use in the capillary tube section of the Plasma Rapid Expansion of Supercritical Solutions (PRESS) process using a carbon dioxide and ethanol mixture as the working fluid. Each method was validated against experimental expansion processes using pure carbon dioxide, isobutane, and R-134a. The results have indicated that both the homogenous flow method and the separated flow method produce results within an acceptable margin of error. By accounting for the phase interactions the separated flow method produces more accurate results with mean errors of 8.03%, 4.57%, and 5.77% for carbon dioxide, isobutane, …

Extensional-Flow-Induced Crystallization Of Polypropylene, Erica E. Bischoff White

Masters Theses 1911 - February 2014

A filament stretching extensional rheometer was used to investigate the effect of uniaxial flow on the crystallization of polypropylene. Samples were heated to a temperature above the melt temperature to erase their thermal and mechanical histories. The Janeschitz-Kriegl protocol was applied and samples were stretched at various extension rates to a final strain of e = 3.0. Differential scanning calorimetry was applied to crystallized samples to measure the degree of crystallinity. The results showed that a minimum extension rate, corresponding to a Weissenberg number of approximately Wi = 1, is required for an increase in percent crystallization to occur. Below …

Multidimensional Modeling Of Condensing Two-Phase Ejector Flow, Michael F. Colarossi

Masters Theses 1911 - February 2014

Condensing ejectors utilize the beneficial thermodynamics of condensation to produce an exiting static pressure that can be in excess of either entering static pressure. The phase change process is driven by both turbulent mixing and interphase heat transfer. Semi-empirical models can be used in conjunction with computational fluid dynamics (CFD) to gain some understanding of how condensing ejectors should be designed and operated.

The current work describes the construction of a multidimensional simulation capability built around an Eulerian pseudo-fluid approach. The transport equations for mass and momentum treat the two phases as a continuous mixture. The fluid is treated as …

Numerical Investigation Of Gas-Particle Supersonic Flow, Mihir A. Samel

Masters Theses 1911 - February 2014

No abstract provided.

Load Hindcasting: A Retrospective Regional Load Prediction Method Using Reanalysis Weather Data, Jonathan D. Black

Masters Theses 1911 - February 2014

The capacity value (CV) of a power generation unit indicates the extent to which it contributes to the generation system adequacy of a region’s bulk power system. Given the capricious nature of the wind resource, determining wind generation’s CV is nontrivial, but can be understood simply as how well its power output temporally correlates with a region’s electricity load during times of system need. Both wind generation and load are governed by weather phenomena that exhibit variability across all timescales, including low frequency weather cycles that span decades. Thus, a data-driven determination of wind’s CV should involve the use of …

Parallel Mesh Adaptation And Graph Analysis Using Graphics Processing Units, Timothy P. Mcguiness

Masters Theses 1911 - February 2014

In the field of Computational Fluid Dynamics, several types of mesh adaptation strategies are used to enhance a mesh’s quality, thereby improving simulation speed and accuracy. Mesh smoothing (r-refinement) is a simple and effective technique, where nodes are repositioned to increase or decrease local mesh resolution. Mesh partitioning divides a mesh into sections, for use on distributed-memory parallel machines. As a more abstract form of modeling, graph theory can be used to simulate many real-world problems, and has applications in the fields of computer science, sociology, engineering and transportation, to name a few. One of the more important graph analysis …

Numerical Forcing Of Horizontally-Homogeneous Stratified Turbulence, Kaustubh J. Rao

Masters Theses 1911 - February 2014

It is often desirable to study simulated turbulent flows at steady state even if the flow has no inherent source of turbulence kinetic energy. Doing so requires a numerical forcing scheme and various methods have been studied extensively for turbulence that is isotropic and homogeneous in three dimensions. A review of these existing schemes is used to form a framework for more general forcing methods. In this framework, the problem of developing a forcing scheme in Fourier space is abstracted into the two problems of (1) prescribing the spectrum of the input power and (2) specifying a force that has …