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A Numerical Investigation Of Human Cough Jet Development And Droplet Dispersion, Ran Bi 2018 The University of Western Ontario

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 ...


Experimental Investigation Of A New Spiral Wingtip, Naseeb Ahmed Siddiqui, Mohamed Aldeeb, Waqar Asrar, Erwin Sulaeman 2018 International Islamic University - Malaysia

Experimental Investigation Of A New Spiral Wingtip, Naseeb Ahmed Siddiqui, Mohamed Aldeeb, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

Experiments on the relative merits and demerits of slotted wingtips mimicking a bird’s primary feathers have been performed. The real emargination length of feather tips, their flexibility and curved shapes during cruise are considered in the present study. The experiments were performed at a Reynolds number of 3.7 x 105 on a symmetric flat plate half wing of aspect ratio 3. Lift, drag and pitching moments were measured using a six component aerodynamic balance. Four different shapes inspired by bird primary feathers have been analysed. The rigid curved tip performed the best increasing the L/D ratio ...


Nonlinear Control Of Underactuated And Constrained Systems, Derek Hoffman 2018 Embry-Riddle Aeronautical University

Nonlinear Control Of Underactuated And Constrained Systems, Derek Hoffman

Dissertations and Theses

It is the purpose of this document to elaborate on the control of systems that are underactuated or otherwise constrained. To do so, local- and global-coordinate formulations are implemented to generate well-defined system dynamics for a multitude of scenarios. These dynamics are shown to lie on manifolds defined by mathematical restrictions, allowing for singularity-free modeling for global considerations. Feed-back controllers by extension share these benefits, facilitating singularity-free control algorithms as a result. Further, unactuated degrees of freedom can be treated as additional constraints, resulting in an embedded manifold upon the original dynamics. A transformation between a provided set of dynamical ...


Nanoindentation Study Of Corrosion-Induced Grain Boundary Degradation In A Pipeline Steel, Denizhan Yavas, Pratyush Mishra, Abdullah Alshehri, Pranav Shrotriya, Kurt R. Hebert, Ashraf F. Bastawros 2018 Iowa State University

Nanoindentation Study Of Corrosion-Induced Grain Boundary Degradation In A Pipeline Steel, Denizhan Yavas, Pratyush Mishra, Abdullah Alshehri, Pranav Shrotriya, Kurt R. Hebert, Ashraf F. Bastawros

Aerospace Engineering Publications

High-strength low-alloy steels used for oil and gas pipelines are vulnerable to intergranular stress corrosion cracking in moderately alkaline soils. The mechanism of corrosion-induced embrittlement under such conditions is not yet understood. Nanoindentation was used to detect localized degradation of mechanical properties near internal grain boundaries of X-70 steel undergoing intergranular corrosion at active dissolution potentials at pH 8.2. The measurements identified a one-micron thick mechanically-degraded layer with 25% reduced hardness near corroded grain boundaries. It is suggested that the corrosion process may introduce an active softening agent, possibly non-equilibrium lattice vacancies generated by oxidation.


Low Reynolds Number Numerical Simulation Of The Aerodynamic Coefficients Of A 3d Wing, Khurshid Malik, Waqar Asrar, Erwin Sulaeman 2018 International Islamic University - Malaysia

Low Reynolds Number Numerical Simulation Of The Aerodynamic Coefficients Of A 3d Wing, Khurshid Malik, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

A low Reynolds number, three-dimensional CFD analysis is carried out for a finite flat plate wing using the commercial CFD code STAR CCM+. The six-aerodynamic force and moment components CL, CD, CM, CN, Cl, CY and their derivatives are computed at a Reynolds numbers of 3x105 by varying the pitch, roll and yaw angles about the quarter chord point. The computed results have been validated with experimental aerodynamic balance data when possible. The results indicate that roll and yaw angle affect the aerodynamic coefficients of the flat plate wing along with the pitch ...


Magnetic Two-Way Valves For Paper-Based Capillary-Driven Microfluidic Devices, Mario Fratzl, Boyce Chang, Stephanie Oyola-Reynoso, Guillaume Blaire, Sarah Delshad, Thibaut Devillers, Thomas Ward, III, Nora M. Dempsey, Jean-Francis Bloch, Martin M. Thuo 2018 Université Grenoble Alpes

Magnetic Two-Way Valves For Paper-Based Capillary-Driven Microfluidic Devices, Mario Fratzl, Boyce Chang, Stephanie Oyola-Reynoso, Guillaume Blaire, Sarah Delshad, Thibaut Devillers, Thomas Ward, Iii, Nora M. Dempsey, Jean-Francis Bloch, Martin M. Thuo

Materials Science and Engineering Publications

This article presents a magnetically actuated two-way, three-position (+, 0, −), paper-based microfluidic valve that includes a neutral position (0)--the first of its kind. The system is highly robust, customizable, and fully automated. The advent of a neutral position and the ability to precisely control switching frequencies establish a new platform for highly controlled fluid flows in paper-based wicking microfluidic devices. The potential utility of these valves is demonstrated in automated, programmed, patterning of dyed liquids in a wicking device akin to a colorimetric assay but with a programmed fluid/reagent delivery. These valves are fabricated using facile methods and thus ...


Base Pressure Control Using Micro-Jets In Supersonic Flow Regimes, Vigneshvaran Sethuraman, Sher Afghan Khan 2018 Monash University Malaysia

Base Pressure Control Using Micro-Jets In Supersonic Flow Regimes, Vigneshvaran Sethuraman, Sher Afghan Khan

International Journal of Aviation, Aeronautics, and Aerospace

Base pressure plays a vital role in aerospace-related applications and its control is essential in reduction of drag and improving fuel consumption. Low pressure at the base of Rockets, Missiles, bombs and shells are a very common problem happening at transonic and supersonic speeds. In most of the cases there is a significant dip in pressure at the base region which will have implications on the design of aerospace vehicles. This paper presents an experimental investigation carried out for flow control at supersonic regimes. Experiments were conducted to measure the base pressure in the base region and wall pressure distribution ...


Numerical Analysis Of Aerodynamic Noise Mitigation Via Leading Edge Serrations For A Rod–Airfoil Configuration, Bharat Raj Agrawal, Anupam Sharma 2018 Iowa State University

Numerical Analysis Of Aerodynamic Noise Mitigation Via Leading Edge Serrations For A Rod–Airfoil Configuration, Bharat Raj Agrawal, Anupam Sharma

Anupam Sharma

Noise produced by aerodynamic interaction between a circular cylinder (rod) and an airfoil in a tandem arrangement is investigated numerically using incompressible large eddy simulations. Quasi-periodic shedding from the rod and the resulting wake impinges on the airfoil to produce unsteady loads on the two geometries. These unsteady loads act as sources of aerodynamic sound and the sound radiates to the far-field with a dipole directivity. The airfoil is set at zero angle of attack for the simulations and the Reynolds number based on the rod diameter is Red = 48 K. Comparisons with experimental measurements are made for (a) mean ...


Wing-Tip Vortex Evolution In Turbulence, Hari Charan Ghimire 2018 University of Kentucky

Wing-Tip Vortex Evolution In Turbulence, Hari Charan Ghimire

Theses and Dissertations--Mechanical Engineering

Planar and stereo particle image velocimetry measurements were conducted of a wing-tip vortex decaying in free-stream turbulence in order to understand the evolution of a vortex and its decay mechanism. The vortex decayed faster in the presence of turbulence. The decay of the circulation was found to be almost entirely due to a decrease in circulation of the vortex core, caused by the relative decrease in peak tangential velocity without a corresponding increase in core radius. These events were found to be connected with the stripping of core fluid from the vortex core. The increased rate of decay of the ...


Guardian Condor, jake stefanick, Matt Wallace, Dan Bologna, Kevin Bayonnet 2018 The University of Akron

Guardian Condor, Jake Stefanick, Matt Wallace, Dan Bologna, Kevin Bayonnet

Honors Research Projects

The group was tasked with designing a 3D printed glider. The scope of this assignment is to someday use the developed glider design and equip it with electronics and controls to deliver medical materials to remote areas in drone-like fashion. The glider was to be designed so that it could be printed using a lower-end, compact, and relatively portable 3D printer for optimal field efficiency. For this reason, the makerbot 3D printer was selected. The compact base plate of the makerbot printer left the team with strict size limitations, so the glider was printed in a series of nine parts ...


Design Of Shape-Conforming Nosecone For Optimal Fluid Flow From Transonic To Supersonic Range, Anna Tombazzi 2018 The University of Akron

Design Of Shape-Conforming Nosecone For Optimal Fluid Flow From Transonic To Supersonic Range, Anna Tombazzi

Honors Research Projects

Modern flight vehicles, such as rockets, missiles, and airplanes, experience a force caused by forebody wave drag during the flight. This drag force is induced when the frontal point of each vehicle breaks the pressure wave during flight. Efforts to reduce this wave drag force to improve flight efficiency include modifying the nosecone profile of the flight vehicles to lower the drag force.

This project revolved around creating a design to make the transformation of nosecone shapes from a ¾ Parabolic profile to a ½ Power Series profile possible, mid-flight. Using a novel nosecone assembly, shape memory alloys (SMAs) and ...


Optimization Of Turbulent Prandtl Number In Turbulent, Wall Bounded Flows, Donald Edward Bernard 2018 University of Vermont

Optimization Of Turbulent Prandtl Number In Turbulent, Wall Bounded Flows, Donald Edward Bernard

Graduate College Dissertations and Theses

After nearly 50 years of development, Computational Fluid Dynamics (CFD) has become an indispensable component of research, forecasting, design, prototyping and testing for a very broad spectrum of fields including geophysics, and most engineering fields (mechanical, aerospace, biomedical, chemical and civil engineering). The fastest and most affordable CFD approach, called Reynolds-Average-Navier-Stokes (RANS) can predict the drag around a car in just a few minutes of simulation. This feat is possible thanks to simplifying assumptions, semi-empirical models and empirical models that render the flow governing equations solvable at low computational costs. The fidelity of RANS model is good to excellent for ...


Large Eddy Simulation Of Oscillatory Flow Over A Rippled Bed Using An Euler-Lagrange Approach, Daniel S. Hagan 2018 University of Vermont

Large Eddy Simulation Of Oscillatory Flow Over A Rippled Bed Using An Euler-Lagrange Approach, Daniel S. Hagan

Graduate College Dissertations and Theses

A volume-filtered Large-Eddy Simulation (LES) of oscillatory flow over a rippled mobile bed is conducted using an Euler-Lagrange approach. As in unsteady marine flows over sedimentary beds, the experimental data, referenced in this work for validation, shows quasi-steady state ripples in the sand bed under oscillatory flow. This work approximately reproduces this configuration with a sinusoidal pressure gradient driven flow and a sinusoidally rippled bed of particles. The LES equations, which are volume-filtered to account for the effect of the particles, are solved on an Eulerian grid, and the particles are tracked in a Lagrangian framework. In the Discrete Particle ...


Single Camera Photogrammetry Matlab Solver Developed For Automation Of The Oil Interferometry Process, Hunter Michael Dunn 2018 California Polytechnic State University, San Luis Obispo

Single Camera Photogrammetry Matlab Solver Developed For Automation Of The Oil Interferometry Process, Hunter Michael Dunn

Master's Theses and Project Reports

Over the last 20 years, Gregory G. Zilliac of the NASA AMES Research Center has been in continuous development of a fringe-imaging skin friction PC application used in oil interferometry analysis. This application, CXWIN5G, allows users to analyze propagation of oil smears across an aerodynamic surface using photogrammetry. The purpose of this thesis is to investigate the feasibility of increasing the level of automation currently found in CXWIN5G by developing a MATLAB solver capable of determining oil smear geometry with minimal user input.

There are two main automation goals of this thesis that are reflected in the core of the ...


Intermittency Effects On The Universality Of Local Dissipation Scales In Turbulent Boundary Layer Flows With And Without Free-Stream Turbulence, Sabah Falih Habeeb Alhamdi 2018 University of Kentucky

Intermittency Effects On The Universality Of Local Dissipation Scales In Turbulent Boundary Layer Flows With And Without Free-Stream Turbulence, Sabah Falih Habeeb Alhamdi

Theses and Dissertations--Mechanical Engineering

Measurements of the small-scale dissipation statistics of turbulent boundary layer flows with and without free-stream turbulence are reported for Reτ ≈ 1000 (Reθ ≈ 2000). The scaling of the dissipation scale distribution is examined in these two boundary conditions of external wall-bounded flow.

Results demonstrated that the local large-scale Reynolds number based on the measured longitudinal integral length-scale fails to properly normalize the dissipation scale distribution near the wall in these two free-stream conditions, due to the imperfect characterization of the upper bound of the inertial cascade by the integral length-scale. When a length-scale based on Townsend's attached-eddy hypothesis ...


Theoretical Paschen's Law Model For Aerospace Vehicles: Validation Experiment, Jaysen Mulligan Aroche 2018 University of Central Florida

Theoretical Paschen's Law Model For Aerospace Vehicles: Validation Experiment, Jaysen Mulligan Aroche

Electronic Theses and Dissertations

Aerospace vehicles often experience triboelectric charging while traversing the atmosphere. Triboelectric charging occurs when a material come into frictional contact with a different material. Aerospace vehicles triboelectrically charge due to frictional contact with dust and ice crystals suspended in the atmosphere. Launch vehicles traversing ice clouds in low-pressure atmosphere are especially prone to electrostatic discharge events (i.e. sparks). These conditions are hazardous and affect the vehicle's launch commit criteria. In 2010, engineers from an ARES-I rocket launch reported concerns with triboelectric charging over their self-destruct system antenna. This concern was addressed by putting the antenna through harsh conditions ...


Structured Light-Field Focusing 3d Density Measurements Of A Supersonic Cone, Ryonosuke Ozawa 2018 University of Central Florida

Structured Light-Field Focusing 3d Density Measurements Of A Supersonic Cone, Ryonosuke Ozawa

Electronic Theses and Dissertations

This study describes three-dimensional (3D) quantitative visualization of density field in a supersonic flow around a cone spike. A measurement of the density gradient is conducted within a supersonic wind tunnel facility at the Propulsion and Energy Research Laboratory at the University of Central Florida utilizing Structured Light-Field Focusing Schlieren (SLLF). In conventional schlieren and Shadowgraph techniques, it is widely known that a complicated optical system is needed and yet visualizable area depends on an effective diameter of lenses and mirrors. Unlike these techniques, SLLF is yet one of the same family as schlieren photography, it is capable of non-intrusive ...


Strongly Coupled Fluid-Particle Flows In Vertical Channels. Ii. Turbulence Modeling, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox 2017 University of Illinois at Urbana-Champaign

Strongly Coupled Fluid-Particle Flows In Vertical Channels. Ii. Turbulence Modeling, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox

Rodney O. Fox

In Part I, simulations of strongly coupled fluid-particle flow in a vertical channel were performed with the purpose of understanding, in general, the fundamental physics of wall-bounded multiphase turbulence and, in particular, the roles of the spatially correlated and uncorrelated components of the particle velocity.The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions were presented, and the unclosed terms that are retained in the context of fully developed channel flow were evaluated in an Eulerian–Lagrangian (EL) framework. Here, data from the EL simulations are used to validate a multiphase Reynolds-stress model (RSM) that predicts the wall-normal distribution of the ...


Strongly Coupled Fluid-Particle Flows In Vertical Channels. I. Reynolds-Averaged Two-Phase Turbulence Statistics, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox 2017 University of Illinois at Urbana-Champaign

Strongly Coupled Fluid-Particle Flows In Vertical Channels. I. Reynolds-Averaged Two-Phase Turbulence Statistics, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox

Rodney O. Fox

Simulations of strongly coupled (i.e., high-mass-loading) fluid-particle flows in vertical channels are performed with the purpose of understanding the fundamental physics of wall-bounded multiphase turbulence. The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions are presented, and the unclosed terms that are retained in the context of fully developed channel flow are evaluated in an Eulerian–Lagrangian (EL) framework for the first time. A key distinction between the RA formulation presented in the current work and previous derivations of multiphase turbulence models is the partitioning of the particle velocity fluctuations into spatially correlated and uncorrelated components, used to define the ...


A Comparison Of The Aerodynamic Centers For Panel Code Compressible Corrections And Openfoam 5 For Mach 0.1 To 0.8, Dustin Weaver 2017 Utah State University

A Comparison Of The Aerodynamic Centers For Panel Code Compressible Corrections And Openfoam 5 For Mach 0.1 To 0.8, Dustin Weaver

All Graduate Plan B and other Reports

It is known that the aerodynamic center changes from quarter chord to half chord from incompressible to compressible flows on airfoils. Compressible corrections are derived and implemented in a vortex panel code. These results will be used to find the aerodynamic centers for the specified Mach range of 0.1 to 0.8 in 0.1 increments within - 6 to 6 degrees angle of attack. OpenFOAM 5 cases will be created with specific meshes and settings. The results calculated from OpenFOAM 5 will be compared to the results obtained from the compressible corrections.


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