Engineering Commons^™

Experimental And Numerical Study Of Dysphagia, Yash G. Potdar

Masters Theses

Dysphagia, meaning difficulty in swallowing, is a symptom of disease that occurs in young children and elderly people. It occurs particularly due to two reasons, weak neural network and/or deformities in oral section/s. The Helen DeVos Children’s Hospital’s Intensive Feeding Program takes care of children suffering from Dysphagia. In order to make the swallowing process easier and in some cases safer, thickener is added to the liquids. Depending on the requirement of thickness, the amount of thickener is varied. Although the directions to prepare the mixtures are given by the thickener product company, the required thickness is not achieved when …

Development Of A One-Equation Eddy Viscosity Turbulence Model For Application To Complex Turbulent Flows, Timothy Wray

McKelvey School of Engineering Theses & Dissertations

Computational fluid dynamics (CFD) is routinely used in performance prediction and design of aircraft, turbomachinery, automobiles, and in many other industrial applications. Despite its wide range of use, deficiencies in its prediction accuracy still exist. One critical weakness is the accurate simulation of complex turbulent flows using the Reynolds-Averaged Navier-Stokes equations in conjunction with a turbulence model. The goal of this research has been to develop an eddy viscosity type turbulence model to increase the accuracy of flow simulations for mildly separated flows, flows with rotation and curvature effects, and flows with surface roughness. It is accomplished by developing a …

Sensitivity Analysis Of Geometry Changes In The Simulation Of Basilar Aneurysms, Paul Eserkaln

Theses and Dissertations

Computer simulation is a useful tool in the research and treatment of basilar aneurysms. Current technology allows researchers to create 3D models from cerebral vasculature in-vivo, allowing for the investigation of surgical options with minimal risk to the patient. The method used to construct these models overlooks smaller lateral arterial branches which are difficult to discern due to resolution limits of the imaging process. These lateral branches have minimal impact on the overall blood flow through the basilar artery, but they play a significant role in the health of the patient, so it is important to ensure sufficient blood will …

Computational Fluid Dynamics Is Key To Better Flying Aircraft, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Optimization Of Water And Energy Use In Indirect Evaporative Cooling System By Cfd, Mansi Vijay Prajapati

Mechanical and Aerospace Engineering Theses

Data center cooling is becoming important to maintain environmental condition for ITE- Information technology equipment. Conventional evaporative wet cooling media lowers the temperature of the dry bulb temperature of incoming air in which heat transfer to water film and sensibly cool the product air by increasing moisture into air. Wet cooling media technique requires large quantity of clean water, which is reducing area where water is very less. Therefore, indirect evaporative cooling is good alternative. Chiller plants/Indirect Evaporative cooling(IEC) are used as a cooling source for larger data centers as they are more efficient in heat transfer without adding moisture …

Reduced Order Fluid-Structure Interaction Models For Thin Shells With Non-Zero Gaussian Curvatures To Understand The Response Of Aneurysms To Flow, Gary Han Chang

Doctoral Dissertations

In this thesis, a reduced-order model is constructed to study the physiological flow and wall shear stress conditions for aneurysms. The method of local proper orthogonal decomposition (POD) is used to construct the reduced-order modes using a series of CFD results, which are subsequently improved using a QR-factorization technique to satisfy the various boundary conditions in physiological flow problems. This method can effectively construct a computationally efficient physiological model, which allows us to examine the fluid velocities and wall shear stress distributions over a range of different physiological flow parameters. Aneurysms are the dilation, bulging, or ballooning-out of part of …

Eulerian Cfd Modeling Of Multiphase Internal Injector Flow And External Sprays, Eli T. Baldwin

Doctoral Dissertations

The improvement of combustion systems which use sprays to atomize liquid fuel requires an understanding of that atomization process. Although the secondary break up mechanisms for the far-field of an atomizing spray have been thoroughly studied and well understood for some time, understanding the internal nozzle flow and primary atomization on which the far-field spray depends has proven to be more of a challenge. Flow through fuel injector nozzles can be highly complex and heavily influenced by factors such as turbulence, needle motion, nozzle imperfections, nozzle asymmetry, and phase change. All of this occurs within metallic injectors, making experimental characterization …

Multiscale Wind Modelling For Sustainability And Resilience, Djordje Romanic

Electronic Thesis and Dissertation Repository

The research presented herein is a mix of meteorological and wind engineering disciplines. In many cases, there is a gap between these two fields and this thesis is an attempt to bridge that gap through multiscale wind modelling approaches. Data and methods used in this study cover a multitude of spatial and temporal scales. Applications are in the fields of sustainability and resilience. This relationship between multiscale wind modelling and sustainability and resilience is investigated examining several case studies of three different developments: urban, rural and coastal.

An urban wind modelling methodology is proposed and applied for a specific development …

Simulation Of The Effect Of Breakwater On The Propagation Of Solitary Waves, Ching-Piao Tsai, Ying-Chi Chen, Chun-Jen Chen, Chang Lin

Journal of Marine Science and Technology

A numerical simulation of the effect of breakwater on the propagation of solitary waves was presented in this study using CFD based on the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the renormalization group (RNG) turbulent model. The wave transformation and the flow field variation of solitary waves propagating over composite breakwaters of different heights were simulated. The effect of breakwater height on the run-up of solitary waves on the slope was discussed. The simulation results revealed a jet-like flow phenomenon when solitary waves passing over breakwaters due to the water level difference between the weather and lee sides of the …

Experimental, Theoretical And Computational Modeling Of Flow Boiling, Flow Condensation And Evaporating Falling Films, Chirag Rajan Kharangate

Open Access Dissertations

The transition from single-phase to two-phase thermal systems in future space vehicles demands a thorough understanding of phase change methods in reduced gravity, including microgravity. In this study, phase change methods like flow boiling, flow condensation and evaporative falling-films are investigated experimentally, theoretically and computationally.

The experimental part of the study consists of an investigation of the influence of inlet subcooling and two-phase inlet on flow boiling heat transfer and critical heat flux in a horizontal 2.5-mm wide by 5-mm high rectangular channel in different orientations with respect to Earth gravity using FC-72 as working fluid. High-speed video imaging is …

A Numerical Study Of The Lateral Hyporheic Flow About A Channels Confluence, C. Gualtieri

International Congress on Environmental Modelling and Software

Stream and pore waters continuously interact and mix within streambeds due to spatial and temporal variations in channel characteristics. This mixing is termed as hyporheic exchange and the zone where groundwater and stream water are mixing is called hyporheic zone, which can greatly affect water quality is both surface and subsurface water systems. Typical examples of hyporheic fluxes are those under bedforms, intra-meander or across point bar deposits, while the lateral and vertical hyporheic exchanges about a riverine confluence was almost never investigated.

The paper presents some results of a numerical study carried out to investigate the basic features of …

Computational Fluid Dynamic Analysis Of Microbubble Drag Reduction Systems At High Reynolds Number, John D. Goolcharan

FIU Electronic Theses and Dissertations

Microbubble drag reduction (MBDR) is an effective method to improve the efficiency of fluid systems. MBDR is a field that has been extensively studied in the past, and experimental values of up to 80% to 90% drag reduction have been obtained. The effectiveness and simplicity of MBDR makes it a viable method for real world applications, particularly in naval applications where it can reduce the drag between the surface of ships and the surrounding water. A two dimensional single phase model was created in ANSYS Fluent to effectively model the behavior of bubble laden flow over a flat plate. This …

Comparison Of Airfoil Precomputational Analysis Methods For Optimization Of Wind Turbine Blades, Ryan Barrett, Andrew Ning

Faculty Publications

The objective of this research was to develop and compare various airfoil precomputational parameterization and analysis techniques for aerostructural optimization of wind turbine blades. The airfoils along the blade were added as optimization design variables through pre-computational parameterization methods using thickness-to-chord ratios and blended airfoil family factors. The airfoils' aerodynamic performance was analyzed with three methods of increasing fidelity: a panel method (XFOIL), Navier-Stokes based computational fluid dynamics (RANS CFD), and wind tunnel data. The optimizations minimized mass over annual energy production (m/AEP) and thereby approximated the minimization of cost of energy. The results were compared to the NREL 5-MW …

Cfd Study Of Decay Function Of Wall Shear Stress With Scour Around Complex-Shape Bridge Pier, Chen Li

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Pier scour problem is close related to the safety of bridges. The Federal Highway Administration of the United State also has a great interest in studying the relation between hydraulic loadings and scour depth. The current technological problem of directly measuring hydraulic loadings on a dynamic bed using physical experiments and the weak capacity to simulate the real scour processes with CFD methods inspired the development of a hybrid approach by combining them to study pier scour.

This research specifically focuses on the CFD part of the hybrid method. A series of three-dimensional (3-D) CFD models were developed with unsteady …

Experimental And Computational Study Of Gas Bubble Removal In A Microfluidic System Using Nanofibrous Membranes, Hamed Gholami Derami, Ravindra Vundavilli, Jeff Darabi

SIUE Faculty Research, Scholarship, and Creative Activity

This paper presents a simple and efficient method for removing gas bubbles from a microfluidic system. This bubble removal system uses a T-junction configuration to generate gas bubbles within a water-filled microchannel. The generated bubbles are then transported to a bubble removal region and vented through a hydrophobic nanofibrous membrane. Four different hydrophobic Polytetrafluorethylene (PTFE) membranes with different pore sizes ranging from 0.45 to 3 μm are tested to study the effect of membrane structure on the system performance. The fluidic channel width is 500 μm and channel height ranges from 100 to 300 μm. Additionally, a 3D computational fluid …

Implementations Of Fourier Methods In Cfd To Analyze Distortion Transfer And Generation Through A Transonic Fan, Marshall Warren Peterson

Theses and Dissertations

Inlet flow distortion is a non-uniform total pressure, total temperature, or swirl (flow angularity) condition at an aircraft engine inlet. Inlet distortion is a critical consideration in modern fan and compressor design. This is especially true as the industry continues to increase the efficiency and operating range of air breathing gas turbine engines. The focus of this paper is to evaluate the Computational Fluid Dynamics (CFD) Harmonic Balance (HB) solver in STAR-CCM+ as a reduced order method for capturing inlet distortion as well as the associated distortion transfer and generation. New methods for quantitatively describing and analyzing distortion transfer and …

Development Of A Three-Dimensional High-Order Strand-Grids Approach, Oisin Tong

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The strand-Cartesian grid approach is a unique method of generating and computing fluid dynamic simulations. The strand-Cartesian approach provides highly desirable qualities of fully-automatic grid generation and high accuracy. This work focuses on development of a high-accuracy methodology (high-order scheme) on strand grids for two and three dimensions.

In this work, the high-order scheme is extended to high-Reynolds number computations in both two and three dimensions with the Spalart-Allmaras turbulence model and the Menter SST turbulence model. In addition, a simple limiter is explored to allow the high-order scheme to accurately predict discontinuous flows.

Extensive verification and validation is conducted …

Computational Fluid Dynamic Modeling Of Natural Convection In Vertically Heated Rods, Mahesh Surendran

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Natural convection is a phenomenon that occurs in a wide range of applications such as cooling towers, air conditioners, and power plants. Natural convection may be used in decay heat removal systems such as spent fuel casks, where the higher reliability inherent of natural convection is more desirable than forced convection. Passive systems, such as natural convection, may provide better safety, and hence have received much attention recently. Cooling of spent fuel rods is conventionally done using water as the coolant. However, it involves contaminating the water with radiation from the fuel rods. Contamination becomes dangerous and difficult for humans …

Numerical And Experimental Study Of Liquid Breakup Process In Solid Rocket Motor Nozzle, Yi-Hsin Yen

Theses and Dissertations

Rocket propulsion is an important travel method for space exploration and national defense, rockets needs to be able to withstand wide range of operation environment and also stable and precise enough to carry sophisticated payload into orbit, those engineering requirement makes rocket becomes one of the state of the art industry. The rocket family have been classified into two major group of liquid and solid rocket based on the fuel phase of liquid or solid state. The solid rocket has the advantages of simple working mechanism, less maintenance and preparing procedure and higher storage safety, those characters of solid rocket …

Maximizing Use Of Air-Side Economization, Direct And Indirect Evaporative Cooling For Energy Efficient Data Centers, Betsegaw Kebede Gebrehiwot

Mechanical and Aerospace Engineering Dissertations

Data centers house information technology (IT) equipment such as servers and network switches which are vital for our networked modern society by providing digital data storage, data processing and connectivity. Data centers house few hundreds to tens of thousands of IT equipment that consume few kilowatt-hours to multi-megawatt-hours of electrical energy that gets dissipated as heat. IT equipment need to be properly cooled so that they operate reliably for their expected lifetime. For air cooled IT equipment, manufacturers provide heat sinks, cold plates, fans, et cetera to remove heat from the vicinity of heat dissipating components and data centers need …

Computational Study And Error Analysis Of An Integrated Sampling-Probe And Gas-Analyzer For Mixing Measurements In Supersonic Flows, Wenbo Zhu

Mechanical and Aerospace Engineering Theses

Concentration probes are employed in supersonic flow mixing experiments for binary gas mixture composition measurements. These measurements are fundamental for the advancement of the scramjet technology. While non-intrusive laser-based methods (such as planar laser-induced fluorescence and filtered Rayleigh scattering) have been developed greatly over the past few decades, intrusive methods (such as concentration probes) still play an essential role in the measurement of mixture composition due to the fact that, with correct application, they do not require further assumptions on the aerothermodynamic states of the investigated mixture, which are often difficult to corroborate. Conversely, such assumptions are essential to the …

Cfd Analysis Of Vapor Chamber With Micro Pillars As Heat Spreader For High Power Electronic Devices, Yasir Aziz Modak

Mechanical and Aerospace Engineering Theses

The recent trend in electronic industry shows that there is large power dissipation from the electronic devices and at the same time their sizes are getting smaller. This large power dissipation takes place in the form of releasing heat energy. It is observed that heat dissipation from the electronic devices is high and source size is small. The high device temperatures result in decreased reliability and increased failure rates. This difficulty can be addressed by controlling the temperatures at the source of heat generation. In chip scale package chip is the major source of heat generation. Thus our priority is …

Design Consideration And Steady State Study Of Thrust Bearings In High Speed Subsonic Applications, Arvind Prabhakar

Mechanical and Aerospace Engineering Theses

Thrust bearings are required to perform at high speeds in various turbomachinery applications causing the nature of fluid flow within the bearings to be in high subsonic as well as supersonic regimes. The motivation of this research is to develop a bearing performance prediction model tailored for high subsonic speeds and large Reynolds numbers. The prime fluid characteristics studied in the thin film for predicting the bearing performance has been achieved by carefully considering inertial, viscous as well as compressible effects within the thin film fluid flow. Fluid inertia is a vital physical phenomenon that plays an important role in …

Performance Evaluation Of Plate-Fin And Pin-Fin Heat Sinks For The Application Of Oil Immersion Cooling And Design Optimization Of Dynamic Cold Plate For The Application Of Warm Water Cooling, Parth Jayeshkumar Soni

Mechanical and Aerospace Engineering Theses

In IT industries, to keep server rooms and data centers cool is a constant challenge for hardware developers and the cooling solution providers. Air cooling is the most widely used approach for thermal management of servers in data centers from many years. However, the scenario is changing gradually as the computational ability of data center is increasing exponentially. Because of increasing computational ability, the heat generated by the servers is increased in such amount that air cooling is not as efficient as it was before. Hence, alternative cooling system is required. In 1970’s the idea of liquid cooling was introduced. …

Cfd Modelling Of Wet Cooling Media And Design Optimization Of Heat Sink For Data Center Application, Shivang Yogeshkumar Desai

Mechanical and Aerospace Engineering Theses

Air cooling is most widely used and economical method of currently available cooling technologies in which heat exchanger plays a vital role in facility designs. Evaporative cooling can be energy efficient than mechanical cooling because it uses water’s enthalpy of vaporization. Wet cooling pads can be used as the direct evaporative cooling system in which pad is made of cellulose fibers those gets wet when water injected. When hot and dry air passes through pad surfaces, water evaporates in the air which cools down air adiabatically increasing humidity. These type of cooling units can be installed in these type of …

Aerodynamics Of Race Car Wings: A Cfd Study, Simon Durrer

Masters Theses

Formula 1 racing is one of the most advanced technological sports. The aerodynamic on open wheel race cars is essential for the performance during a race. The front wing on a race car produces about 30 percent of the entire downforce of a race car. Several studies on front wings for open wheel race cars are conducted by various authors. A number of research studies include single element airfoils in ground effect and undisturbed flow. Numerical and experimental studies show that by decreasing the ground clearance, the downforce increases. The most efficient ground clearance is reported to be approximately 10 …

Modified Numerical-Analytical Analysis On Scpps, Nima Fathi, Seyed Sobhan Aleyasin, Peter Vorobieff

Nima Fathi

Case Study Of Quantifying Energy Loss Through Ceiling-Attic Recessed Lighting Fixtures Through 3d Numerical Simulation, Ri Na, Shengmao Lin, Zhigang Shen, Linxia Gu

Durham School of Architectural Engineering and Construction: Faculty Publications

Air leakage through improperly installed recessed lighting fixtures has been identified as a common issue causing extra energy consumption of residential buildings. However, little quantitative study was found in this area. In this paper, a preliminary evaluation of the magnitude of such energy loss was conducted by numerical simulations using 3 dimensional transient computational fluid dynamics (CFD) model. A typical layout of recessed lighting fixtures was used in this case study with boundary conditions in four different seasons, which were obtained from past measured roof/attic temperature data sets. The results of the numerical simulations indicate that leakage of recessed lighting …

Understanding The Effect Of Extrusion Processing Parameters On Physical, Nutritional And Rheological Properties Of Soy White Flakes Based Aquafeed In A Single Screw Extruder, Sushil Kumar Singh

Electronic Theses and Dissertations

The rapid expansion of aquaculture has increased the demand for aquafeed. As fishmeal is expensive, alternative plant based protein sources such as soybean has shown to be a good alternative for aquafeed production. The present study was done to investigate the effect of soy white flakes (SWF) as an alternative source of protein in the production of aquaculture feed through extrusion processing. Ingredient blends containing different levels of SWF along with distiller dried grains, corn flour, corn gluten meal, fish meal, vitamin and mineral mix with net protein adjusted to 32% protein were formulated. The ingredient blends were extruded in …

Design And Analysis Of An Axisymmetric Aerospike Supersonic Micro-Nozzle For A Refrigerant-Based Cold-Gas Propulsion System For Small Satellites, Abdalla Ali Bani

Masters Theses

"The cold-gas propulsion system being developed by M-SAT requires improvements to its original nozzle design. This study documents the research, design, and analysis of a supersonic plug nozzle concept that could be integrated to the refrigerant-based cold-gas propulsion system to possibly improve its performance. As documented in this thesis, CFD analysis showed that the outlined nozzle design method resulted in a feasible nozzle concept that has the ability to out-perform a conventional nozzle of the same area ratio. The flow-fields and thrust of the aerospike nozzle, for the full and truncated nozzles, were investigated. The purpose of this study is …