Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus,
2019
Air Force Institute of Technology
Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt
Theses and Dissertations
Wind tunnels play an indispensable role in the process of aircraft design, providing a test bed to produce valuable, accurate data that can be extrapolated to actual flight conditions. Historically, time-averaged data has made up the bulk of wind tunnel research, but modern flight design necessitates the use of dynamic wind tunnel testing to provide time-accurate data for high frequency motion. This research explores the use of a 6 degree of freedom (DOF) motion test apparatus (MTA) in the form of a robotic arm to allow models inside a subsonic wind tunnel to track prescribed trajectories to obtain time-accurate force …
Jet Rebound From Hydrophobic Substrates In Microgravity,
2019
Portland State University
Jet Rebound From Hydrophobic Substrates In Microgravity, Karl Jeffrey Theodore Cardin
Dissertations and Theses
We experimentally investigate the phenomena of large jet rebound, a mode of fluid transfer following oblique jet impacts on hydrophobic substrates. We initially seek to describe the jet rebound regimes in tests conducted in the weightless environment of a drop tower. A parametric study reveals the dependence of the flow structure on the relevant dimensionless groups such as Reynolds number and Weber number defined on the velocity component perpendicular to the substrate. We show that significantly larger diameter jets behave similarly as much smaller jets demonstrated during previous terrestrial investigations is some parameter ranges while the flow is fundamentally different …
Optimal Homotopy Asymptotic Solution For Thermal Radiation And Chemical Reaction Effects On Electrical Mhd Jeffrey Fluid Flow Over A Stretching Sheet Through Porous Media With Heat Source,
2019
Osmania University
Optimal Homotopy Asymptotic Solution For Thermal Radiation And Chemical Reaction Effects On Electrical Mhd Jeffrey Fluid Flow Over A Stretching Sheet Through Porous Media With Heat Source, Gossaye Aliy, Naikoti Kishan
Applications and Applied Mathematics: An International Journal (AAM)
In this paper, the problem of thermal radiation and chemical reaction effects on electrical MHD Jeffrey fluid flow over a stretching surface through a porous medium with the heat source is presented. We obtained the approximate analytical solution of the nonlinear differential equations governing the problem using the Optimal Homotopy Asymptotic Method (OHAM). Comparison of results has been made with the numerical solutions from the literature, and a very good agreement has been observed. Subsequently, effects of governing parameters of the velocity, temperature and concentration profiles are presented graphically and discussed.
Mhd Boundary Layer Flow Of Darcy-Forchheimer Mixed Convection In A Nanofluid Saturated Porous Media With Viscous Dissipation,
2019
Institute of Aeronautical Engineering
Mhd Boundary Layer Flow Of Darcy-Forchheimer Mixed Convection In A Nanofluid Saturated Porous Media With Viscous Dissipation, S. Jagadha, P. Amrutha
Applications and Applied Mathematics: An International Journal (AAM)
The steady laminar viscous incompressible nanofluid flow of mixed convection and mass transfer about an isothermal vertical flat plate embedded in Darcy porous medium in the presence of magnetic field and viscous dissipation is analyzed. The governing partial differential equations are converted into ordinary differential equations by similarity transformations. The coupled nonlinear ordinary differential equations are linearized by Quasi-linearization technique. The linear ordinary differential equations are solved by using implicit finite difference scheme with the help of C-programming. Numerical calculations are carried out for different values of dimensionless parameter such as magnetic field, mixed convection parameter, inertia parameter, buoyancy ratio …
Water Entry Of Spheres At Various Contact Angles,
2019
Utah State University
Water Entry Of Spheres At Various Contact Angles, Nathan B. Spiers, Mohammad M. Mansoor, Jesse Belden, Tadd T. Truscott
Mechanical and Aerospace Engineering Faculty Publications
It is well known that the water entry of a sphere causes cavity formation above a critical impact velocity as a function of the solid-liquid contact angle (Duez et al. 2007). Using a rough sphere with a contact angle of 120◦, Aristoff & Bush (2009) showed that there are four different cavity shapes dependent on the Bond and Weber numbers (i.e., quasi-static, shallow, deep and surface). We experimentally alter the Bond number, Weber number and contact angle of smooth spheres and find two key additions to the literature: 1) Cavity shape also depends on the contact angle; 2) …
Temporal And Spatial Scaling Of Dissipation Under Non-Breaking Surface Waves,
2019
University of Miami
Temporal And Spatial Scaling Of Dissipation Under Non-Breaking Surface Waves, Mingming Shao, Brian K. Haus, Darek Bogucki, Mohammad Barzegar
Supplementary Data and Tools
This dataset is associated to the NSF OCE/Physical Oceanography funded project “Laboratory Investigation of Turbulence Generation by Surface Waves”. There are three papers in preparation that will refer to data contained within this archive. The overarching goal of this project was to address a significant knowledge gap regarding the turbulent dissipation of non-breaking surface waves. To accomplish this, a comprehensive study in the SUrge-STructure-Atmosphere-INteraction (SUSTAIN) wind-wave laboratory at the University of Miami was conducted. A combination of established measurement approaches (Particle Image Velocimetry (PIV) and Vertical Microstructure Profiler (VMP)) and new technologies (Optical Turbulence Sensor (OTS)) have been used carry …
Memory In A Contact Line,
2019
California Polytechnic State University, San Luis Obispo
Memory In A Contact Line, Charity Lizardo, Esmeralda Orozco, Audrey Profeta, Nathan C. Keim
STAR Program Research Presentations
We study the behavior of the liquid-solid-vapor contact line of water held in a narrow gap between two plates. A syringe pump injects and withdraws a constant, small volume of the water, driving the contact line back and forth repeatedly and changing its shape. We take photos of the contact line after each cycle. Comparing subsequent images to each other, we find that after several cycles the contact line reaches one of two steady states: a reversible steady state, where the shape is not changing, or a fluctuating steady state, where the shape continues to change slightly. Experiments on acrylic …
A Study Of Several Applications Of Parallel Computing In The Sciences Using Petsc,
2019
South Dakota State University
A Study Of Several Applications Of Parallel Computing In The Sciences Using Petsc, Nicholas Stegmeier
Electronic Theses and Dissertations
The importance of computing in the natural sciences continues to grow as scientists strive to analyze complex phenomena. The dynamics of turbulence, astrophysics simulations, and climate change are just a few examples where computing is critical. These problems are computationally intractable on all computing platforms except supercomputers, necessitating the continued development of efficient algorithms and methodologies in parallel computing. This thesis investigates the use of parallel computing and mathematical modeling in the natural sciences through several applications, namely computational fluid dynamics for impinging jets in mechanical engineering, simulation of biofilms in an aqueous environment in mathematical biology, and the solution …
Giardia Lamblia Growth In Viscoelastic Fluids,
2019
Claremont McKenna College
Giardia Lamblia Growth In Viscoelastic Fluids, Kelly Watanabe
CMC Senior Theses
Giardia lamblia is a single-celled protozoan parasite that when ingested, causes diarrheal disease and infects 33% of people in developing countries. Previous studies observe Giardia in water-like fluids, but Giardia's infectious environment consists of viscoelastic mucus in the small intestine. Therefore, Giardia was cultured in viscoelastic fluids, and its population growth was observed in vitro. To create shear-thinning viscoelastic fluids, 0.2% and 0.4% long-chain polyacrylamide (LCPAM) was added to cell culture media. Giardia was cultured in control media, 0.2% LCPAM, and 0.4% LCPAM, and population growth was quantitatively determined over time. Increasing LCPAM concentration resulted in a solution with …
Aerosol-Cloud Interactions In Turbulent Clouds: A Combined Cloud Chamber And Theoretical Study,
2019
Michigan Technological University
Aerosol-Cloud Interactions In Turbulent Clouds: A Combined Cloud Chamber And Theoretical Study, Kamal Kant Chandrakar
Dissertations, Master's Theses and Master's Reports
The influence of aerosol concentration on the cloud droplet size distribution is investigated in a laboratory chamber that enables turbulent cloud formation through moist convection. In chapter 2, moist Rayleigh-Bénard convection with water saturated boundaries is explored using a one-dimensional-turbulence model. This study provides some background about supersaturation statistics in moist convection. Chapters 3 - 7 discuss the experimental and theoretical investigation of aerosol-cloud interactions and cloud droplet size-distributions in turbulent conditions. The experiments are performed in a way so that steady-state microphysics are achieved, with aerosol input balanced by cloud droplet growth and fallout. As aerosol concentration is increased …
Light Propagation Through A Turbulent Cloud: Comparison Of Measured And Computed Extinction,
2019
Michigan Technological University
Light Propagation Through A Turbulent Cloud: Comparison Of Measured And Computed Extinction, Eduardo Rodriguez-Feo Bermudez
Dissertations, Master's Theses and Master's Reports
Remote sensing techniques used for measurement of atmospheric cloud properties operate under the notion that light extinction caused by scattering and absorption is exponential due to Beer-Lambert law. This is expected to be valid for a uni-form medium with no spatial correlations between particle position. The aim of this research was to show that under turbulent conditions, cloud droplets cannot be interpreted as non-correlated, and in turn will exhibit a lower than exponential light decay from scattering. The research took place at the MTU π-Chamber laboratory. A temperature difference between the floor and ceiling of the chamber was applied to …
Surface Waves Over Currents And Uneven Bottom,
2019
Technological University Dublin
Surface Waves Over Currents And Uneven Bottom, Alan Compelli, Rossen Ivanov, Calin I. Martin, Michail D. Todorov
Articles
The propagation of surface water waves interacting with a current and an uneven bottom is studied. Such a situation is typical for ocean waves where the winds generate currents in the top layer of the ocean. The role of the bottom topography is taken into account since it also influences the local wave and current patterns. Specific scaling of the variables is selected which leads to approximations of Boussinesq and KdV types. The arising KdV equation with variable coefficients, dependent on the bottom topography, is studied numerically when the initial condition is in the form of the one soliton solution …
Optimization And Control Of Arrays Of Wave Energy Converters,
2019
Michigan Technological University
Optimization And Control Of Arrays Of Wave Energy Converters, Jianyang Lyu
Dissertations, Master's Theses and Master's Reports
Wave Energy Converter Array is a practical approach to harvest ocean wave energy. To leverage the potential of the WEC array in terms of energy extraction, it is essential to have a properly designed array configuration and control system. This thesis explores the optimal configuration of Wave Energy Converters (WECs) arrays and their optimal control. The optimization of the WEC array allows both dimensions of individual WECs as well as the array layout to varying. In the first optimization problem, cylindrical buoys are assumed in the array where their radii and drafts are optimization parameters. Genetic Algorithms are used for …
Microfluidic Study Of Gravity-Driven Drainage And Coalescence Of Aqueous Two Dimensional Foams,
2019
CUNY City College
Microfluidic Study Of Gravity-Driven Drainage And Coalescence Of Aqueous Two Dimensional Foams, Justin D. Heftel
Dissertations and Theses
Foams, a two-phase dispersion, are staples of the cosmetic, personal care, petroleum, pharmaceutical, and other industries. Central to these applications is the stability of the dispersion against separation. Foams break down by two mechanisms: the first is bubble coalescence, which is driven by the gravity drainage of the continuous phase. The drainage acts to push the bubbles against each other, and leads to the formation of thin lamellae, which break and cause the coalescence. The second is the mass transfer of the dispersed phase through the continuous phase, which is caused by the difference in pressures between the bubbles and …
Adhesion At Solid/Liquid Interfaces,
2019
Virginia Commonwealth University
Adhesion At Solid/Liquid Interfaces, Neda Ojaghlou
Theses and Dissertations
The adhesion at solid/liquid interface plays a fundamental role in diverse fields and helps explain the structure and physical properties of interfaces, at the atomic scale, for example in catalysis, crystal growth, lubrication, electrochemistry, colloidal system, and in many biological reactions. Unraveling the atomic structure at the solid/liquid interface is, therefore, one of the major challenges facing the surface science today to understand the physical processes in the phenomena such as surface coating, self-cleaning, and oil recovery applications. In this thesis, a variety of theory/computational methods in statistical physics and statistical mechanics are used to improve understanding of water adhesion …
Equatorial Wave–Current Interactions,
2019
University of Vienna
Equatorial Wave–Current Interactions, Adrian Constantin, Rossen Ivanov
Articles
We study the nonlinear equations of motion for equatorial wave–current interactions in the physically realistic setting of azimuthal two-dimensional inviscid flows with piecewise constant vorticity in a two-layer fluid with a flat bed and a free surface. We derive a Hamiltonian formulation for the nonlinear governing equations that is adequate for structure-preserving perturbations, at the linear and at the nonlinear level. Linear theory reveals some important features of the dynamics, highlighting differences between the short- and long-wave regimes. The fact that ocean energy is concentrated in the long-wave propagation modes motivates the pursuit of in-depth nonlinear analysis in the long-wave …
Soret Effect On Transient Mhd Convective Flow Past A Semi-Infinite Vertical Porous Plate With Heat Sink And Chemical Reaction,
2018
Gauhati University
Soret Effect On Transient Mhd Convective Flow Past A Semi-Infinite Vertical Porous Plate With Heat Sink And Chemical Reaction, K. Choudhury, N. Ahmed
Applications and Applied Mathematics: An International Journal (AAM)
This problem concerns with an analytical study of heat and mass transfer on unsteady MHD convective flow past a semi-infinite porous vertical plate in presence of thermal diffusion, heat sink and chemical reaction. A uniform magnetic field is imposed transversely to the plate. The governing equations are solved by perturbation technique. The expressions for the velocity, temperature and concentration fields as well as transport properties are obtained in non-dimensional form. The influence of the physical parameters like magnetic field parameter, Schmidt number, Prandtl number, heat sink parameter, chemical reaction parameter and Soret number on these fields is discussed through graphs …
Quasi-Linearization Method With Rational Legendre Collocation Method For Solving Mhd Flow Over A Stretching Sheet With Variable Thickness And Slip Velocity Which Embedded In A Porous Medium,
2018
Al Imam Mohammad Ibn Saud Islamic University (IMSIU)
Quasi-Linearization Method With Rational Legendre Collocation Method For Solving Mhd Flow Over A Stretching Sheet With Variable Thickness And Slip Velocity Which Embedded In A Porous Medium, M. M. Khader
Applications and Applied Mathematics: An International Journal (AAM)
The quasi-linearization method (QLM) and the rational Legendre functions are introduced here to present the numerical solution for the Newtonian fluid flow past an impermeable stretching sheet which embedded in a porous medium with a power-law surface velocity, variable thickness and slip velocity. Firstly, due to the high nonlinearity which yielded from the ordinary differential equation which describes the proposed physical problem, we construct a sequence of linear ODEs by using the QLM, hence the resulted equations become a system of linear algebraic equations. The comparison with the available results in the literature review proves that the obtained results via …
Similarity Analysis Of Three Dimensional Nanofluid Flow By Deductive Group Theoretic Method,
2018
Government Engg. College, Gandhinagar
Similarity Analysis Of Three Dimensional Nanofluid Flow By Deductive Group Theoretic Method, Hemangini Shukla, Hema C. Surati, M. G. Timol
Applications and Applied Mathematics: An International Journal (AAM)
The objective of this paper is to obtain similarity solution of three-dimensional nanofluid flow over flat surface stretched continuously in two lateral directions. Two independent variables from governing equations are reduced by applying deductive two parameter group theoretical method. Partial differential equations with boundary conditions are converted into ordinary differential equations with appropriate boundary conditions. Obtained equations are solved for temperature and velocity. The effect of nanoparticles volume fraction on temperature and velocity profile is investigated.
Numerical Studies For Mhd Flow And Gradient Heat Transport Past A Stretching Sheet With Radiation And Heat Production Via Dtm,
2018
Taif University
Numerical Studies For Mhd Flow And Gradient Heat Transport Past A Stretching Sheet With Radiation And Heat Production Via Dtm, Khadijah M. Abualnaja
Applications and Applied Mathematics: An International Journal (AAM)
This paper presents a numerically study for the effect of the internal heat generation, magnetic field and thermal radiation effects on the flow and gradient heat transfer of a Newtonian fluid over a stretching sheet. By using a similarity transformation, the governing PDEs can be transformed into a coupled non-linear system of ODEs with variable coefficients. Numerical solutions for these equations subject to appropriate boundary conditions are obtained by using the differential transformation method (DTM). The effects of various physical parameters such as viscosity parameter, the suction parameter, the radiation parameter, internal heat generation or absorption parameter and the Prandtl …
