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Theses/Dissertations

2018

CFD

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Full-Text Articles in Engineering

Cfd Modeling Of Smoke Movement In An Atrium, Robin Wu Dec 2018

Cfd Modeling Of Smoke Movement In An Atrium, Robin Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this paper is to better understand the behavior of smoke movement in an atrium. Thus gives first responders and civilians in and out of building a better understanding

With the advancements of modern technology, computers and softwares make simulation models possible such as fire models to simulate fire and smoke movements. In this paper, a computational fluid dynamic (CFD) software Fire Dynamic Simulator (FDS) is used to conduct a series of atrium tests to investigate the effectiveness of smoke exhaust systems. FDS solves the Navier-Stokes equations appropriate for low speed flows (Ma < 0.3) with an emphasis on smoke, heat transport and CO2 concentrations from fires. The default turbulence model used in FDS simulation is the Large Eddy Simulation (LES), which is the solution of Navier-Stokes equations at low speed.

The compartment tested was 9 …


Wall Shear Stress In Simplified And Scanned Avian Respiratory Airways, Michael Sterling Farnsworth Dec 2018

Wall Shear Stress In Simplified And Scanned Avian Respiratory Airways, Michael Sterling Farnsworth

Theses and Dissertations

Birds uniquely produce sound through a vocal organ known as a syrinx. The presence of wall shear stress acting on the airway cells of any organism will affect how airway cells develop and multiply. Unique features of avian airway geometry and breathing pattern might have contributed to the development of the syrinx. This thesis examines wall shear stress in the trachea and first bronchi of avian geometries using computational fluid dynamics. The computational fluid dynamic simulations underwent grid- and time-independence studies and were validated using particle image velocimetry. Parameters such as bird size, bronchial branching angle, and breathing waveform were …


Analysis Of The Effects Of Inlet Distortion On Stall Cell Formation In A Transonic Compressor Using Create-Av Kestrel, Mikkel Andreas Unrau Dec 2018

Analysis Of The Effects Of Inlet Distortion On Stall Cell Formation In A Transonic Compressor Using Create-Av Kestrel, Mikkel Andreas Unrau

Theses and Dissertations

Accurately predicting fan performance, including bounds of operation, is an important function of any Computational Fluid Dynamics (CFD) package. The presented research uses a CFD code developed as part of the Computational Research and Engineering Acquisition Tools and Environment (CREATE), known as Kestrel, to evaluate a single stage compressor at various operating conditions. Steady-state, single-passage simulations are carried out to validate capabilities recently added to Kestrel. The analysis includes generating speedlines of total pressure ratio and efficiency, as well as radial total temperature and total pressure profiles at two axial locations in the compressor at various operating conditions and fan …


Investigating The Effect Of An Upstream Spheroid On Tandem Hydrofoils, Joel Tynan Guerra Dec 2018

Investigating The Effect Of An Upstream Spheroid On Tandem Hydrofoils, Joel Tynan Guerra

Master's Theses

This thesis documents a series of three dimensional unsteady Reynolds Averaged Navier-Stokes CFD simulations used to investigate the influence of an upstream prolate spheroid body on tandem pitching hydrofoils. The model is validated by performing separate CFD simulations on the body and pitching hydrofoils and comparing results to existing experimental data. The simulations were run for a range of Strouhal numbers (0.2-0.5) and phase differences (0-π). Results were compared to identical simulations without an upstream body to determine how the body affects thrust generation and the unsteady flow field.

The combined time-averaged thrust increases with Strouhal number, and is highest …


Effect Of Aerogel On The Thermal Performance Of Corrugated Composite Sandwich Structures, Jacob Dillon Chess Dec 2018

Effect Of Aerogel On The Thermal Performance Of Corrugated Composite Sandwich Structures, Jacob Dillon Chess

Master's Theses

Current insulation solutions across multiple industries, especially the commercial sector, can be bulky and ineffective when considering their volume. Aerogels are excellent insulators, exhibiting low thermal conductivities and low densities with a porosity of around 95%. Such characteristics make aerogels effective in decreasing conductive heat transfer within a solid. These requirements are crucial for aerospace and spaceflight applications, where sensitive components exist among extreme temperature environments. When implemented into insulation applications, aerogel can perform better than existing technology while using less material, which limits the amount of volume allocated for insulation. The application of these materials into composites can result …


Fluid Agitation Studies For Drug Product Containers Using Computational Fluid Dynamics, Matthew Hiroki Ichinose Dec 2018

Fluid Agitation Studies For Drug Product Containers Using Computational Fluid Dynamics, Matthew Hiroki Ichinose

Master's Theses

At Amgen, the Automated Vision Inspection (AVI) systems capture the movement of unwanted particles in Amgen's drug product containers. For quality inspection, the AVI system must detect these undesired particles using a high speed spin-stop agitation process. To better understand the fluid movements to swirl the particles away from the walls, Computational Fluid Dynamics (CFD) is used to analyze the nature of the two phase flow of air and a liquid solution.

Several 2-D and 3-D models were developed using Fluent to create simulations of Amgen's drug product containers for a 1 mL syringe, 2.25 mL syringe, and a 5 …


A Computational Fluid Dynamics (Cfd) Analysis Of The Aerodynamic Effects Of The Seams On A Two-Dimensional Representation Of A Soccer Ball, Allen R. Rohr Dec 2018

A Computational Fluid Dynamics (Cfd) Analysis Of The Aerodynamic Effects Of The Seams On A Two-Dimensional Representation Of A Soccer Ball, Allen R. Rohr

Master's Theses

Most major sports today use a dedicated ball or projectile with specific shape, size, and surface geometry, except for soccer. Over the history of the sport, the surface geometry and design stayed relatively unchanged, sewn together using 32 pentagonal and hexagonal panels. However, recent innovations in panel designs differ substantially from the traditional 32 panel ball. The effects these new designs have on the aerodynamic characteristics of the ball have remained largely unknown, even with the influx of experimental research completed in the past decade. Experimental studies have been broad in scope, analyzing an entire ball in wind tunnels or …


Micro-Nozzle Simulation And Test For An Electrothermal Plasma Thruster, Tyler J. Croteau Dec 2018

Micro-Nozzle Simulation And Test For An Electrothermal Plasma Thruster, Tyler J. Croteau

Master's Theses

With an increased demand in Cube Satellite (CubeSat) development for low cost science and exploration missions, a push for the development of micro-propulsion technology has emerged, which seeks to increase CubeSat capabilities for novel mission concepts. One type of micro-propulsion system currently under development, known as Pocket Rocket, is an electrothermal plasma micro-thruster.

Pocket Rocket uses a capacitively coupled plasma, generated by radio-frequency, in order to provide neutral gas heating via ion-neutral collisions within a gas discharge tube. When compared to a cold-gas thruster of similar size, this gas heating mechanism allows Pocket Rocket to increase the exit thermal velocity …


Turbulent Mixers For Protein Folding Experiments, Venkatesh Inguva Nov 2018

Turbulent Mixers For Protein Folding Experiments, Venkatesh Inguva

Doctoral Dissertations

Protein folding studies require the development of micro-mixers that require less sample, mix at faster rates, and still provide a high signal to noise ratio. Chaotic to marginally turbulent micro-mixers are promising candidates for this application. In this study, various turbulence and unsteadiness generation concepts are explored that avoid cavitation. The mixing enhancements include flow turning regions, flow splitters, and vortex shedding. The relative effectiveness of these different approaches for rapid micro-mixing is discussed. Simulations found that flow turning regions provided the best mixing profile. Various turbulence models are simulated to determine appropriate model of the design requirements. Experimental validation …


Computational Exploration Of Flash-Boiling Internal Flow And Near-Nozzle Spray, Sampath K. Rachakonda Oct 2018

Computational Exploration Of Flash-Boiling Internal Flow And Near-Nozzle Spray, Sampath K. Rachakonda

Doctoral Dissertations

Gasoline engines operating under the principle of direct injection are susceptible to flash-boiling due to superheated nature of the fuel and the sub-atmospheric in-cylinder pressures during injection. A review of the literature on flash-boiling sprays shows that a majority of the studies have focused on the far-field regions of the spray, with limited attention given to understanding the influences of the injector geometry and the near-nozzle regions of the spray. Modeling the internal nozzle flow and the primary atomization, on which the far-field spray depends, is a challenge. This thesis, therefore, is aimed at understanding the complex flow through a …


Liquid Jet Penetration And Breakup In A Free Supersonic Gas Jet, Hansen Jones Oct 2018

Liquid Jet Penetration And Breakup In A Free Supersonic Gas Jet, Hansen Jones

LSU Master's Theses

In the testing of today’s rocket engines, both on large scale vertical test stands and smaller subscale horizontal component testing stands, it is extremely important to be able to accurately quantify and mitigate the thermal and acoustic loads the engines will generate on test stand infrastructure. Due to the large number of parameters that must be considered for many cases, development of a multi-phase computational code is under way to properly analyze and design water spray cooling systems used at NASA’s Stennis Space Center (SSC) and across other NASA centers. As such, a small-scale experiment has been conducted at Louisiana …


Development And Application Of Rotation And Curvature Correction To Wray-Agarwal Turbulence Model, Xiao Zhang Aug 2018

Development And Application Of Rotation And Curvature Correction To Wray-Agarwal Turbulence Model, Xiao Zhang

McKelvey School of Engineering Theses & Dissertations

Computational Fluid Dynamics (CFD) is increasingly playing a significant role in the analysis and design of aircrafts, turbomachines, automobiles, and in many other industrial applications. In majority of the applications, the fluid flow is generally turbulent. The accurate prediction of turbulent flows to date remains a challenging problem in CFD. In almost all industrial applications, Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a turbulence model are employed for simulation and prediction of turbulent flows. Currently the one-equation (namely the Spalart-Allmaras (SA) and Wray-Agarwal (WA) and two-equation (namely the k-ε and Shear Stress Transport k-ω) turbulence models remain the most widely …


Numerical Investigations Of Bubble Column Equipped With Vertical Internals In Different Arrangements, Tuntun Gaurav Aug 2018

Numerical Investigations Of Bubble Column Equipped With Vertical Internals In Different Arrangements, Tuntun Gaurav

Electronic Thesis and Dissertation Repository

Bubble columns are multiphase contactors with wide applications in industrial processes. Often they are equipped with longitudinal tube bundles to facilitate heat exchange. Studying effects of these internals on column hydrodynamics is vital for the design of these internals. Computational Fluid Dynamic (CFD) simulations provide an understanding of the complex two-phase flow enabling the study of the effects of the internals on the column hydrodynamics. In the present work, an Eulerian-Eulerian based two-fluid model (TFM) coupled with a population balance model (PBM) is used to simulate the gas-liquid two-phase flows in bubble columns. The models studied were validated using experimental …


Computer Modeling Of Close-To-Ground Tornado Wind-Fields For Different Tornado Widths, Mohammadhossein Kashefizadeh Aug 2018

Computer Modeling Of Close-To-Ground Tornado Wind-Fields For Different Tornado Widths, Mohammadhossein Kashefizadeh

Graduate Theses and Dissertations

Tornadoes induce different wind forces on buildings than straight-line (SL) winds. The tangential velocity (Vθ) of tornados is the main parameter that causes damage to the buildings. In-field tornado measurements cannot evaluate the tornado’s Vθ at less than 20m above ground level (AGL). The laboratory tornado simulators suggest that the Swirl ratio (S) and the radius (ro) are the most influential factors affecting Vθ. However, due to scaling problems, laboratory simulators cannot report the Vθ for elevations less than 10m AGL. Well refined computational fluid dynamics (CFD) models can evaluate the Vθ at less than 10m AGL. However, the CFD …


Validation Of Cfd Simulations For Hypersonic Flow Over A Yawed Cone, Julian Cecil May 2018

Validation Of Cfd Simulations For Hypersonic Flow Over A Yawed Cone, Julian Cecil

McKelvey School of Engineering Theses & Dissertations

This study aims to numerically simulate the wind tunnel results for hypersonic flow over a circular cone of semi-apex angle of 10 degrees yawed from 0° to 20° using the commercial computational fluid dynamics software ANSYS Fluent. The ANSYS workbench is used to create the 10° semi-apex circular cone with a shock aligned structured mesh of 3.05 million cells surrounding the cone. Simulation boundary conditions for pressure and temperature in the far field correspond to Tracy’s wind tunnel experiment at Cal Tech. The six simulations cases are conducted for yaw angles of 0, 8, 12, 16, 20 and 24 degrees. …


Computational Fluid Dynamics Model For Air Velocity Through A Poultry Transport Trailer In A Holding Shed, Christian Heymsfield May 2018

Computational Fluid Dynamics Model For Air Velocity Through A Poultry Transport Trailer In A Holding Shed, Christian Heymsfield

Graduate Theses and Dissertations

Broiler production in Arkansas was valued at over $3.6 billion in 2013 (University of Arkansas Division of Agriculture Cooperative Extension Service). Consequently, improvement in any phase of the production process can have significant economic impact and animal welfare implications. One area of concern for the poultry industry is thermal stress experienced by the birds after arrival at the processing plant and before they are taken in to be processed, during which time they are left to wait in holding sheds. Various cooling strategies exist to mitigate heat stress in holding sheds, but in most cases it is unlikely that they …


Comparing Stenotic Blood Flow In Three- And Two-Dimensional Arterial Renderings Using Computational Fluid Dynamics And Multiphase Mean Age Theory., Jacob S. Garza May 2018

Comparing Stenotic Blood Flow In Three- And Two-Dimensional Arterial Renderings Using Computational Fluid Dynamics And Multiphase Mean Age Theory., Jacob S. Garza

Electronic Theses and Dissertations

Over one million invasive coronary angiography procedures are performed annually in patients who experience chest pain or are known to have coronary artery disease. The procedure is carried out to ascertain the degree of arterial blockage (stenosis) that hinders blood flow to the heart. A cardiologist performing the procedure determines the physiological degree of a stenosis by either visual estimation, which is routine practice, or by invasively measuring fractional flow reserve (FFR), which is the current gold standard that has been demonstrated to improve patient outcomes and temper the cost of healthcare. Nevertheless, FFR is performed in only 10–20% of …


Immersive Visualization In Biomedical Computational Fluid Dynamics And Didactic Teaching And Learning, John Thomas Venn Apr 2018

Immersive Visualization In Biomedical Computational Fluid Dynamics And Didactic Teaching And Learning, John Thomas Venn

Master's Theses (2009 -)

Virtual reality (VR) can stimulate active learning, critical thinking, decision making and improved performance. It requires a medium to show virtual content, which is called a virtual environment (VE). The MARquette Visualization Lab (MARVL) is an example of a VE. Robust processes and workflows that allow for the creation of content for use within MARVL further increases the userbase for this valuable resource. A workflow was created to display biomedical computational fluid dynamics (CFD) and complementary data in a wide range of VE’s. This allows a researcher to study the simulation in its natural three-dimensional (3D) morphology. In addition, it …


Investigation Of Microfluidic Kelvin Water Dropper And Its Applications In Contact And Contactless Electrowetting, Elias Yazdanshenas Apr 2018

Investigation Of Microfluidic Kelvin Water Dropper And Its Applications In Contact And Contactless Electrowetting, Elias Yazdanshenas

Mechanical & Aerospace Engineering Theses & Dissertations

A typical Kelvin water dropper is a device that can convert gravitational potential energy to a high voltage electrostatic. This device consists of two inductors, two collectors, tubes, and electrical connections. A Kelvin water dropper is able to generate extremely high voltage by separating ions using two positive feedback loops. A Kelvin water dropper provides a low cost solution for the applications in which high voltage is needed. In the present research, low cost Microfluidic Kelvin Water Droppers (MKWDs) were developed and built in house for electrowetting applications. Two MKWDs with different tube inner diameters (254 and 508 μm) were …


A Cfd Assisted Closed-Loop Control System Design For The 37-Element Canadian Scwr Under Full Load Condition, Huirui Han Feb 2018

A Cfd Assisted Closed-Loop Control System Design For The 37-Element Canadian Scwr Under Full Load Condition, Huirui Han

Electronic Thesis and Dissertation Repository

A method to design the closed-loop control system for the 37-element vertical Canadian supercritical water-cooled reactor (SCWR) fuel bundle has been proposed in this study. The dynamic models used in the controller design are obtained based on the computational fluid dynamics (CFD) simulations of the fluid flow and heat transfer of the supercritical water in the SCWR fuel bundle. The Reynolds Stress Model is used in the CFD simulations. Comparisons of the supercritical water flow behaviors and heat transfer phenomenon in the single- rod channel and multi-rod channel are also carried out. The results show that there are secondary flows …


An Experimental And Computational Study Of Fuel Spray Interaction: Fundamentals And Engine Applications, Le Zhao Jan 2018

An Experimental And Computational Study Of Fuel Spray Interaction: Fundamentals And Engine Applications, Le Zhao

Dissertations, Master's Theses and Master's Reports

An efficient spray injection results in better vaporization and air-fuel mixing, leading to combustion stability and reduction of emissions in the internal combustion (IC) engines. The impingement of liquid fuels on chamber wall or piston surface in IC engines is a common phenomenon and fuel film formed in the spray-piston or cylinder wall impingement plays a critical role in engine performance and emissions. Therefore, the study of the spray impingement on the chamber wall or position surface is necessary.

To understand the spray-wall interaction, a single droplet impingement on a solid surface with different conditions was first examined. The droplet-wall …


Coupling Computational Fluid Dynamics Analysis And Optimization Techniques For Scramjet Engine Design, Nathan T. Mcgillivray Jan 2018

Coupling Computational Fluid Dynamics Analysis And Optimization Techniques For Scramjet Engine Design, Nathan T. Mcgillivray

Browse all Theses and Dissertations

Various aspects of hypersonic vehicles are being rapidly explored for improved functionality. One of the main areas of consideration is the fueling of a Supersonic Combusting Ramjet (scramjet) engine. Using Computational Fluid Dynamics (CFD), computer simulations can be performed to analyze the flow physics of a scramjet. In this research, an optimization code, Dakota, is integrated with the CFD to optimize a set of parameters to maximum thrust. In this study, the fuel injection and combustion is replaced with heat sources. This simplification greatly reduces the computational requirements. Additionally, the 3D geometry is reduced to an axisymmetric 2D geometry because …


Design Of A Novel Tissue Culture System To Subject Aortic Tissue To Multidirectional Bicuspid Aortic Valve Wall Shear Stress, Janet Liu Jan 2018

Design Of A Novel Tissue Culture System To Subject Aortic Tissue To Multidirectional Bicuspid Aortic Valve Wall Shear Stress, Janet Liu

Browse all Theses and Dissertations

Blood vessels experience complex hemodynamics marked by three-dimensionality and pulsatility. Arterial endothelial cells interact with the characteristics of the fluid wall shear stress (WSS) to maintain homeostasis or promote disease states. In particular, the bicuspid aortic valve (BAV), a congenital heart valve anatomy consisting of two leaflets instead of three, is associated with aortic complications presumably promoted by hemodynamic abnormalities. While devices have been used to test this hypothesis, their capabilities are limited to the generation of time-varying WSS magnitude in one direction. However, the increased flow helicity generated by BAVs in the aorta is expected to result in increased …


Hydrodynamics Related Performance Evaluation Of Upflow Moving Bed Hydrotreater Reactor (Mbr) Using Developed Experimental Methods And Cfd Simulation, Vineet Alexander Jan 2018

Hydrodynamics Related Performance Evaluation Of Upflow Moving Bed Hydrotreater Reactor (Mbr) Using Developed Experimental Methods And Cfd Simulation, Vineet Alexander

Doctoral Dissertations

"Upflow Moving Bed Hydrotreater (MBR) reactor is used for hydrotreating resid crude oil. It is a two-phase upflow reactor having a catalyst bed with conical bottom, and plena. At industrial conditions the reactor is not performing at its best and encountering issues such as hot spots, catalyst agglomeration inside the catalyst bed leading to frequent shutdown of the reactor. The root cause of these problems are linked to the improper hydrodynamics inside the catalyst bed. To investigate this, the industrial scale MBR is scaled down to a pilot scale and indicative and key hydrodynamic parameters are investigated using developed experimental …


Geometric Optimization Of A Heaving Point Absorber Wave Energy Converter, Ian Riley Jan 2018

Geometric Optimization Of A Heaving Point Absorber Wave Energy Converter, Ian Riley

Electronic Theses and Dissertations

Wave energy shows significant potential for development into a competitive renewable energy source. Non-renewable resources are finite and contribute to adverse effects on the environment. Development of wave energy conversion devices that use heave motion as the primary driver for converting wave energy into electrical potential is explored through optimizing the geometry of an axisymmetric partially submerged buoy in deep water. The governing equations of motion and hydrodynamic forces are solved for in one degree of freedom using ANSYS Aqwa. An external PTO device is simulated to induce power capture in the system. Four different geometric shapes are tested and …