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Full-Text Articles in Engineering

An Experimental Study On The Impact Of Pressure Drop In The Ranque-Hilsch Vortex Tube, Mark Parker Aug 2019

An Experimental Study On The Impact Of Pressure Drop In The Ranque-Hilsch Vortex Tube, Mark Parker

Electronic Thesis and Dissertation Repository

A vortex tube converts a single stream of compressed gas into two outlet streams; one heated, and the other cooled. This phenomenon, referred to as energy separation, is not fully understood, thereby requires further experimentation and analysis. CFD can provide insight, however, such simulations require a complete set of information of the geometric, operational, and performance parameters of particular vortex tube experiments.

An experiment is developed to provide complete information for CFD simulations. The vortex tube under consideration is established by considering reported data from past studies and selecting parameters that yield significant energy separation. An experimental apparatus is developed ...


Pneumatic Hyperelastic Robotic End-Effector For Grasping Soft Curved Organic Objects, Alexandre Galley Aug 2019

Pneumatic Hyperelastic Robotic End-Effector For Grasping Soft Curved Organic Objects, Alexandre Galley

Electronic Thesis and Dissertation Repository

Pneumatically-driven soft robotic grippers can elastically deform to grasp delicate, curved organic objects with minimal surface damage. However, common actuators have complex geometries and are fabricated with ultra-soft hyperelastic elastomers not originally intended for scientific applications. The complexity of the actuator geometry and extreme nonlinearity of their material’s stress-strain behaviour make it difficult to predict the actuator’s deformation prior to experimentation. In this work, a compact soft pneumatic gripper made with polydimethylsiloxane (PDMS) is developed for grasping delicate organic objects, analyzed through computational modelling and experimentally validated. COMSOL Multiphysics is used to simulate the impact of geometrical parameters ...


Effects Of Grooves On Drag In Laminar Channel Flow, Yanbei Wang Jul 2018

Effects Of Grooves On Drag In Laminar Channel Flow, Yanbei Wang

Electronic Thesis and Dissertation Repository

This thesis presents the analysis of the effects of three-dimensional grooves on the flow responses in laminar channel flows. The wall topographies were expressed using the two-dimensional Fourier expansions. A spectrally accurate algorithm based on the Immersed Boundary Conditions (IBC) was used to determine the solution for the field equations and extract information about the velocity and pressure fields. The effects of grooves on the pressure losses were assessed by determining the additional pressure gradient required to maintain the same flow rate through the grooved channel as through the reference smooth channel. Effects of groove wave numbers, groove amplitudes, the ...


Dynamics Of The Phase Coupling For Flow, Heat And Mass Transfer In Conjugate Fluid/Porous Domains, Mahmoud Mohamed Mostafa Elhalwagy Jun 2018

Dynamics Of The Phase Coupling For Flow, Heat And Mass Transfer In Conjugate Fluid/Porous Domains, Mahmoud Mohamed Mostafa Elhalwagy

Electronic Thesis and Dissertation Repository

Porous media prevail in industry e.g. heat transfer equipment, drying, food storage and several other applications. Integrated in engineering, they form conjugate Fluid/Porous domains. Physical modelling requires characterizing the microscale heat and mass (moisture) transfer interstitially within porous media and their macroscale counterparts across regional interfaces. Characterizing turbulence and its effects on phase coupling is often needed too. The modeling literature survey shows phase coupling assumptions depending on empiricism, phase equilibrium and lack of generality. Modeling of the dynamic variations for the modes of phase exchanges, i.e. heat, mass and heat accompanying mass exchanges, on both scales ...


A Numerical Investigation Of Human Cough Jet Development And Droplet Dispersion, Ran Bi Apr 2018

A Numerical Investigation Of Human Cough Jet Development And Droplet Dispersion, Ran Bi

Electronic Thesis and Dissertation Repository

As part of the Western Cold and Flu aerosol (WeCoF) studies, the present study provides Computational Fluid Dynamics (CFD) modelling of human cough flow. The cough flow is characterized in two different aspects, the flow field and the droplets. In the study of the flow field of coughing, various dynamic characteristics, including the velocity variation, streamwise penetration and power spectral density, are examined. CFD simulations using two different approaches, the unsteady Reynolds Averaged Navier-Stokes (URANS) and the large eddy simulation (LES), are performed for comparison purposes. The numerical results are validated by the experimental data obtained from the measurements by ...


Fabrication Of 3d Conjugated Polymer Structures Via Vat Polymerization Additive Manufacturing, Andrew T. Cullen Apr 2018

Fabrication Of 3d Conjugated Polymer Structures Via Vat Polymerization Additive Manufacturing, Andrew T. Cullen

Electronic Thesis and Dissertation Repository

Conjugated polymers are a class of electromechanically active materials that can produce motion in response to an electric potential. This motion can be harnessed to perform mechanical work, and therefore these materials are particularly well suited for use as sensors and actuators in microelectromechanical systems. Conventional methods to fabricate conjugated polymer actuators result in planar morphologies that limit fabricated devices to simplistic linear or bending actuation modes. To overcome this limitation, this work develops a conjugated polymer formulation and associated additive manufacturing method capable of realizing three-dimensional conductive polymer structures. A light-based additive manufacturing technique known as vat polymerization is ...


A Numerical Tool For Predicting The Spatial Decay Of Freestream Turbulence., Dwaipayan Sarkar Apr 2018

A Numerical Tool For Predicting The Spatial Decay Of Freestream Turbulence., Dwaipayan Sarkar

Electronic Thesis and Dissertation Repository

The present numerical work is an attempt towards modelling of freely decaying homogeneous isotropic turbulence with its application in experimental modelling of the effect of incident turbulence on flow around 2D and 3D bluff-bodies. Both steady, Reynolds Averaged Navier Stokes (RANS) and unsteady, Large Eddy Simulation (LES), 3-D numerical computational fluid dynamics (CFD) techniques have been employed to characterise the inviscid decay of large-scale turbulence in terms of the characteristic r.m.s turbulent velocity fluctuations ( ) and the local integral length scale (Lu). The large-scale turbulent properties extracted from the current numerical simulations are inter-related and are shown to ...


Experimental Simulation Of Density-Driven Thunderstorm Downbursts, Roghayyeh Babaei Koli Apr 2018

Experimental Simulation Of Density-Driven Thunderstorm Downbursts, Roghayyeh Babaei Koli

Electronic Thesis and Dissertation Repository

Evaporative cooling of the precipitation within the thunderstorm cloud results in the formation of a mass of cold and dense air which moves toward the ground and after impingement turns into strong radial winds near the surface. In this study, an experimental approach was taken to investigate the downbursts. The two-fluid model was used, and the various features of the experimental setup of previous researchers were modified to incorporate the specifications of natural downbursts. First, two new release cylinders were manufactured and their capabilities in producing repeatable and symmetric outflows were examined. Then, the effects of cylinder wall design, density ...


Free-Surface Wall-Jet Flow At Moderate Reynolds Number As Applied To Slot And Blade Coating, Mohammad Tanvir Hossain Nov 2017

Free-Surface Wall-Jet Flow At Moderate Reynolds Number As Applied To Slot And Blade Coating, Mohammad Tanvir Hossain

Electronic Thesis and Dissertation Repository

The flow of a two-dimensional steady wall jet observed in the slot and blade coating processes has been examined theoretically near the channel exit. The Newtonian free surface jet emerges from a channel and deposits onto an infinite moving wall with an adverse or favorable pressure gradient applied inside the channel. The Reynolds number considered is within the moderate range, and fully developed Couette-Poisueille flow conditions are assumed to prevail far upstream inside the channel. The effects of inertia and pressure gradient on the velocity, the shape of the free surface, and the stress are emphasized. It is found that ...


The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet Sep 2017

The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet

Electronic Thesis and Dissertation Repository

The motivation of this thesis is the development of simple microscopic-scale model (representative elemental volume; REV) that can be used to conduct flow and heat transfer simulations from which closure coefficients can be established for the volume-averaged transport equations for porous media (packed bed). The thesis provides a brief introduction to the computational technique adopted for the geometric generation of the REV (YADE), followed by a parametric study undertaken to reveal the minimum number of particles inside the REV that are required to mimic the appropriate physics. Additional analysis was conducted with the goal of determining the influence of deviation ...


Numerical Simulations Of Two-Phase Flows In The Liquid Solid Circulating Fluidized Bed, Hao Luo Sep 2017

Numerical Simulations Of Two-Phase Flows In The Liquid Solid Circulating Fluidized Bed, Hao Luo

Electronic Thesis and Dissertation Repository

The liquid-solid circulating fluidized bed (LSCFB) has many potential applications in biochemical and petroleum industries, as well as in wastewater treatments, given its higher contact efficiency and being able to accommodate two reactions under one system. With extensive experimental results becoming available, there is clearly a need for computational fluid dynamics (CFD) modeling to expand our understandings of LSCFBs and to predict the hydrodynamic behaviors of the two-phase flows within LSCFB.

In this research, the Eulerian-Eulerian two-phase model combined with the kinetic theory for the granular phase is applied to simulate the two-phase flows in LSCFBs. The key factors affecting ...


Experimental Measurements Of Far Field Cough Airflows Produced By Healthy And Influenza- Infected Human Subjects, Ahmed Faraj Alarbi Mohamed Sep 2017

Experimental Measurements Of Far Field Cough Airflows Produced By Healthy And Influenza- Infected Human Subjects, Ahmed Faraj Alarbi Mohamed

Electronic Thesis and Dissertation Repository

The present work details an experimental study of the cough airflow fields produced by subjects infected with influenza and when they are convalescent, together with data from healthy cohorts. The PIV and HWA measurements were taken far downstream at 1 m from the source within a cough chamber, along with droplet sampling at two different locations and nasal swabs from the sick subjects. The measured data over different seasons were used to evaluate and compare the results from sick, convalescent and healthy subjects. Although a total of 8 sick participants from winter 2014 and 2017 yielded positive nasal swab analysis ...


Fabrication Of Large Mechanically Flexible Multi-Layered Pdms Optical Devices, Robert S. Green Sep 2016

Fabrication Of Large Mechanically Flexible Multi-Layered Pdms Optical Devices, Robert S. Green

Electronic Thesis and Dissertation Repository

Mechanically flexible large area polydimethylsiloxane (PDMS) optical devices are fabricated using soft-lithography techniques based on replica moulding. These non-rigid optical devices can be designed as sheets to act as either light concentrators (collectors) or diffusers (illuminators) based on the position and geometry of micro-optical structures (MOSs) embedded within the sheet or imprinted on its surface. The active surface area of the device can range from less than a sq. cm to several sq. m. The performance of the large area optical device is a function of the location and geometry of micro-optical structures, thickness and shape of the flexible waveguide ...


Parametric Design, Modeling, And Optical Evaluation Of Retroreflective Prismatic Structures, Sama Hussein Aug 2016

Parametric Design, Modeling, And Optical Evaluation Of Retroreflective Prismatic Structures, Sama Hussein

Electronic Thesis and Dissertation Repository

Retroreflectors (RR) are defined as passive optical structures that redirect incident light to its originating source. Specific types of retroreflectors called inverted cubes (ICs) function through total internal reflection (TIR) and are used in various applications such as measurement tools, traffic signs and automotive rear and side lighting. This thesis aims to model, analyze, fabricate and study a novel type of IC retroreflectors called right triangular prism (RTP). A parametric approach is used to model existing IC geometries from a generic unit cube and is then implemented to model the novel RTP geometry. Those elements are then tested by optical ...


The Effect Of Mesh-Type Bubble Breakers On Two-Phase Vertical Co-Flow, Alan Kalbfleisch Jun 2016

The Effect Of Mesh-Type Bubble Breakers On Two-Phase Vertical Co-Flow, Alan Kalbfleisch

Electronic Thesis and Dissertation Repository

It is proposed that mesh-type bubble breakers can be used in two-phase gas-liquid vertical cocurrent pipe flow to enhance the heat and mass transfer rates. Two experimental studies were performed to investigate the effect of mesh-type bubble breakers with varying geometries on two-phase flow behaviour. The first used highspeed imaging to measure bubble size and observe the resulting flow regime for two-phase vertical co-flow consisting of air and water. A Froude number correlation that can be used to predict the bubble size generated by mesh-type bubble breakers is proposed. Flow regime maps for two-phase flow in the presence of bubble ...


Thermal Modeling For Light Armored Vehicle, Marc-André H. Brooks May 2016

Thermal Modeling For Light Armored Vehicle, Marc-André H. Brooks

Electronic Thesis and Dissertation Repository

Light Armored vehicles are required to operate in a variety of extremely hot and arid climates. As such, these vehicles are often subject to large heat gains due to environmental factors. The current systems employed for vehicle cooling do not always perform to the levels that are required, mainly due to the lack of a good estimate of the cooling load. A thermal analog circuit was created which separated each of the heat sources into its own module. Using material properties provided by General Dynamics Land Systems as well as information from acquired from CFD studies and ASHRAE, the values ...


Numerical Investigation Of Full Scale Thunderstorm Downbursts: A Parametric Study And Comparison To Meteorological Model, Christopher Oreskovic Apr 2016

Numerical Investigation Of Full Scale Thunderstorm Downbursts: A Parametric Study And Comparison To Meteorological Model, Christopher Oreskovic

Electronic Thesis and Dissertation Repository

A series of Large Eddy Simulations using an atmospheric meteorological cloud model have been used to investigate the important geometric and thermal parameters that influence a thunderstorm downburst outflow, as it pertains specifically to the idealized cooling source model. A separate set of Large Eddy Simulations make use of the same idealized cooling source model, in a realistic atmospheric base state using real field sounding data, in an attempt to make a quantifiable comparison to a downburst from a full cloud simulation. Randomness has been added to the cooling source forcing function to mimic the thermal variation in a real ...


Application Of Natural Convection For Photovoltaic Cooling And Photocatalytic Disinfection, Usman J. Rajput Mar 2016

Application Of Natural Convection For Photovoltaic Cooling And Photocatalytic Disinfection, Usman J. Rajput

Electronic Thesis and Dissertation Repository

Two investigations for improving renewable technologies are engaged. First is the examination of the enhancement of heat transfer at the rear of a hot photovoltaic panel by natural convection using various configurations and the other is analyzing a new photocatalytic collector for water heating and cleaning. A 20 Watt polycrystalline panel is exposed to indoor simulated solar light, under constant ambient temperature and stagnant wind conditions. Three configurations are considered: a partial heat sink, a water cavity and a water channel. The experimentally obtained convective heat transfer coefficients are 4.4 W•m-2•K-1 at the rear of ...


Studies In Small Scale Thermal Convection, Daniel F. Stranges Nov 2014

Studies In Small Scale Thermal Convection, Daniel F. Stranges

Electronic Thesis and Dissertation Repository

The effect of non-Fourier heat transfer and partial-slip boundary conditions in Rayleigh-Bénard are analyzed theoretically. Non-Fourier fluids possess a relaxation time that reflects the delay in the response of the heat flux to a change in the temperature gradient while the partial slip boundary condition assumes that the fluid velocity and temperature are not equal to that of the wall. Both non-Fourier and partial-slip effects become important when small-scale heat transfer applications are investigated such as convection around micro- and nano-devices as suggested by the extended heat transport equations from kinetic theory. Other applications are also known to exhibit one ...


Digital Generation And Radiation In Spherical-Void-Phase Porous Media, Nolan J. Dyck Sep 2014

Digital Generation And Radiation In Spherical-Void-Phase Porous Media, Nolan J. Dyck

Electronic Thesis and Dissertation Repository

This thesis documents a novel method for method to generate digital samples of spherical void phase foams to predict effective hydraulic, thermal and radiative properties with the intention of assessing the viability of carbon foam as a volumetric solar receiver. The method employs discrete element modeling software to simulate the compression of spherical bubbles into a fully periodic, cubic domain. These domains were subsequently used to determine a variety of effective transport properties to be used in porous media design problems. The predicted properties agreed well with those obtained through experimental and other numerical methods, notably predicting more accurate properties ...


Development And Assessment Of An Impact Apparatus And High-Speed Camera Motion Tracking System To Quantify The Effect Of Static Muscle Loads On Fracture Threshold Measures In The Distal Radius, Jacob M. Reeves Aug 2013

Development And Assessment Of An Impact Apparatus And High-Speed Camera Motion Tracking System To Quantify The Effect Of Static Muscle Loads On Fracture Threshold Measures In The Distal Radius, Jacob M. Reeves

Electronic Thesis and Dissertation Repository

Distal radius fractures are prevalent, debilitating, and costly. This thesis conducts an in vitro investigation of these injuries, examining the role of static muscle loading on fracture threshold measures (i.e., force, impulse, energy). Initially, an impact apparatus and custom LabVIEW colour-thresholding program were designed and assessed for repeatability and accuracy in quantifying fracture measures and impact kinematics. These tools were then used to test six pairs of cadaveric forearms, with static muscle loads simulated in one specimen from each pair. Distal radius fractures were achieved in 5 pairs, with perilunate dislocations in the remaining pair. None of the fracture ...


Experimental Investigation Of Wind Effect On Solar Panels, Ayodeji Abiola-Ogedengbe Apr 2013

Experimental Investigation Of Wind Effect On Solar Panels, Ayodeji Abiola-Ogedengbe

Electronic Thesis and Dissertation Repository

Photovoltaic Solar Panels for electricity generation are outdoor low-rise structures that are vulnerable to damage by the wind. The existing building codes do not contain information about the impact of the wind on these structures and hence do not provide comprehensive guidelines to mitigate such impact. The present study is a contribution to the ongoing efforts to codify the wind loading on solar panels. In this study, experimental investigations were conducted on the scaled model of a ground-mounted solar panel structure whose surface is geometrically similar to an inclined flat plate and mounted on three-legged support. The panel comprises of ...


Numerical Modelling Of Species Exchange In A 3d Porous Medium: Modelling Exchange Within The Human Lung, Chelsea E. Johnson Apr 2013

Numerical Modelling Of Species Exchange In A 3d Porous Medium: Modelling Exchange Within The Human Lung, Chelsea E. Johnson

Electronic Thesis and Dissertation Repository

The volume-averaged oxygen transport equation is closed using a volume-averaged form of Fick’s law of diffusion between the air and tissue to simulate species exchange within the lungs’ alveoli using a computational fluid dynamics (CFD) 3D conjugate domain model. Pore level simulations of a terminal alveolated duct are used to determine that the transport of inhaled oxygen from the cluster inlet to the alveolar walls is diffusion dominated. The resistance to oxygen diffusion into the tissue is found to be a function of the tidal volume and tissue transport properties, with a maximum respiration frequency at which the full ...


Parametric Study On A Novel Waste Heat Recovery System, Ghaleb Rustom Abdul Sater Dec 2012

Parametric Study On A Novel Waste Heat Recovery System, Ghaleb Rustom Abdul Sater

Electronic Thesis and Dissertation Repository

The present thesis is based on an industry-sponsor project involving a novel waste heat-to-electricity conversion system. This proprietary system utilizes thermal energy from a low temperature heat sources to produce torque that drives an electric generator to produce electricity. The system needs to be studied through scientific research to help with optimizing the product development, component design, and overall system performance. The main objectives of this study are to develop simulation tools (numerical model) that will allow to simulate the thermo-fluid processes in various system components and to use this numerical model to study the heat transfer and phase-change processes ...


Studies In Shallow And Thin-Film Flows, Md Mahmuder R. Faisal Oct 2012

Studies In Shallow And Thin-Film Flows, Md Mahmuder R. Faisal

Electronic Thesis and Dissertation Repository

The present study examines the influences of surface tension and wind direction in shallow or thin-film flow with the inclusion of inertial effect. In this present study starting with the fundamental equations (conservation of mass and momentum), an analytical method is introduced to determine the bottom stress at different position of a shallow or thin-film flow domain under the influence of oscillatory wind conditions. The novelty of this study is that the viscous and surface tension effects are considered in this study, whereas in most of the existing studies in a shallow or thin-film flow domain (a shallow tailings pond ...


Improved Non-Linear Solution Of Dip Coating Flow, Omar Bin Yusuf Aug 2012

Improved Non-Linear Solution Of Dip Coating Flow, Omar Bin Yusuf

Electronic Thesis and Dissertation Repository

A thin layer of film is developed on the surface of a substrate in the dip coating process where the substrate is initially immersed into the coating fluid and then withdrawn continuously from the coating fluid bath. In this study a two dimensional flow of the thin film for a Newtonian fluid is examined theoretically by dividing the film into three separate regions. A general formulation is developed for a thin film flow, which then simplifies for each region upon considering appropriate assumptions to each region. The influence of inertia and surface tension in the presence of gravity is investigated ...


Preoperative Planning Of Robotics-Assisted Minimally Invasive Cardiac Surgery Under Uncertainty, Hamidreza Azimian Aug 2012

Preoperative Planning Of Robotics-Assisted Minimally Invasive Cardiac Surgery Under Uncertainty, Hamidreza Azimian

Electronic Thesis and Dissertation Repository

In this thesis, a computational framework for patient-specific preoperative planning of Robotics-Assisted Minimally Invasive Cardiac Surgery (RAMICS) is developed. It is expected that preoperative planning of RAMICS will improve the rate of success by considering robot kinematics, patient-specific thoracic anatomy, and procedure-specific intraoperative conditions. Given the significant anatomical features localized in the preoperative computed tomography images of a patient's thorax, port locations and robot orientations (with respect to the patient's body coordinate frame) are determined to optimize characteristics such as dexterity, reachability, tool approach angles and maneuverability. In this thesis, two approaches for preoperative planning of RAMICS are ...


On-Line Monitoring Of Engine Health Through The Analysis Of Contaminants In Engine Lubricant, Hamid R. Aghayan Apr 2012

On-Line Monitoring Of Engine Health Through The Analysis Of Contaminants In Engine Lubricant, Hamid R. Aghayan

Electronic Thesis and Dissertation Repository

Monitoring automobile liquids, such as engine lubricants, has received increasing attention recently mainly due to environmental and safety legislation, coat saving measures, and customer demand.

Literature review in monitoring engine lubricant condition indicates systems approach, an intellectual discipline method to address complex problem, has never been used to monitor engine performance and health through the engine sub-systems such as lubricant system. The literature review also points toward deficiency in considering lubricant as a source of information for engine performance evaluation, and lack of understanding of engine lubricant as a medium with random properties.

Engine lubricant condition reflects the state of ...