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Articles 1 - 20 of 20
Full-Text Articles in Physics
Entry Of A Sphere Into A Water-Surfactant Mixture And The Effect Of A Bubble Layer, Nathan B. Spiers, Mohammad M. Mansoor, Randy Craig Hurd, Saberul I. Sharker, W. G. Robinson, B. J. Williams, Tadd T. Truscott
Entry Of A Sphere Into A Water-Surfactant Mixture And The Effect Of A Bubble Layer, Nathan B. Spiers, Mohammad M. Mansoor, Randy Craig Hurd, Saberul I. Sharker, W. G. Robinson, B. J. Williams, Tadd T. Truscott
Mechanical and Aerospace Engineering Faculty Publications
A rigid sphere entering a liquid bath does not always produce an entrained air cavity. Previous experimental work shows that cavity formation, or the lack thereof, is governed by fluid properties, wetting properties of the sphere, and impact velocity. In this study, wetting steel spheres are dropped into a water-surfactant mixture with and without passing through a bubble layer first. Surprisingly, in the case of a water-surfactant mixture without a bubble layer, the critical velocity for cavity formation becomes radius dependent. This occurs due to dynamic surface tension effects, with the local surface tension in the splash increasing during surface …
Fluted Films, Nathan B. Spiers, Mohammad M. Mansoor, Jesse Belden, Randy Craig Hurd, Zhao Pan, Tadd T. Truscott
Fluted Films, Nathan B. Spiers, Mohammad M. Mansoor, Jesse Belden, Randy Craig Hurd, Zhao Pan, Tadd T. Truscott
Mechanical and Aerospace Engineering Faculty Publications
This paper is associated with a poster winner of a 2017 APS/DFD Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original poster is available from the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2017.GFM.P0030
Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren
Interface Model Of Pem Fuel Cell Membrane Steady-Dtate Behavior, Russell L. Edwards, Ayodeji Demuren
Mechanical & Aerospace Engineering Faculty Publications
Modeling works which simulate the proton-exchange membrane fuel cell with the computational fluid dynamics approach involve the simultaneous solution of multiple, interconnected physics equations for fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts vary by how they treat the physics within and adjacent to the membrane-electrode assembly (MEA). Certain approaches treat the MEA not as part of the computational domain, but rather an interface connecting the anode and cathode computational domains. These approaches may lack the ability to consistently model catalyst layer losses and MEA ohmic resistance. This work presents an upgraded interface formulation …
Floating Active Baffles, System And Method Of Slosh Damping Comprising The Same, Dae Won Kim, Rudy L. Baum, Vijay Santhanam, Balaji Sivasubramanian, Sathya Gangadharan
Floating Active Baffles, System And Method Of Slosh Damping Comprising The Same, Dae Won Kim, Rudy L. Baum, Vijay Santhanam, Balaji Sivasubramanian, Sathya Gangadharan
Publications
This disclosure provides a system for damping slosh of a liquid within a tank, a baffle for use in the system, and a method of damping slosh using the system. The system includes a plurality of baffles. Each baffle has a body configured to substantially float upon the liquid. Each baffle also has an activation material received along at least a portion of the body. The activation material is magnetically reactive provided in a quantity sufficient to enable the body to be manipulated in the presence of a magnetic field (M). The system further includes an actuator configured to provide …
Reversible Motion In A Contact Line, Audrey Profeta, Esmeralda Orozco, Juan A. Ortiz Salazar, Dani Medina, Nathan C. Keim
Reversible Motion In A Contact Line, Audrey Profeta, Esmeralda Orozco, Juan A. Ortiz Salazar, Dani Medina, Nathan C. Keim
STAR Program Research Presentations
When a body of liquid sits on a surface, an irregular border between the wet and dry regions of the surface exists, called the contact line. Driving this contact line back and forth repeatedly can change its shape.We use a syringe pump to cyclically infuse and withdraw a predetermined volume of water, and take photos of the contact line after each cycle. Comparing these images to each other determines if the contact line is returning to the same shape. We find that below a critical value of infused volume, after many cycles the contact line reaches a steady state in …
Drainage, Rebound And Oscillation Of A Meniscus In A Tube, Jeremy Marston, Garrett Toyofuku, Chao Li, Tadd T. Truscott, Jamal Uddin
Drainage, Rebound And Oscillation Of A Meniscus In A Tube, Jeremy Marston, Garrett Toyofuku, Chao Li, Tadd T. Truscott, Jamal Uddin
Mechanical and Aerospace Engineering Faculty Publications
In this paper, the drainage and subsequent rebound of a liquid column in a cylindrical tube is examined experimentally and theoretically. When liquid is drawn up into a capillary and then released under gravity, inertia allows the meniscus to overshoot the equilibrium capillary rise height. The meniscus then rebounds up the tube, again overshooting the equilibrium height and undergoes oscillation. By varying both the immersion depth and radius of the tube, one can observe rich dynamical behavior, with the most dramatic being the formation of a fast liquid jet, barely visible to the naked eye but easily captured with high-speed …
Patient-Specific Multiscale Computational Fluid Dynamics Assessment Of Embolization Rates In The Hybrid Norwood: Effects Of Size And Placement Of The Reverse Blalock–Taussig Shunt, Ray Prather, John Seligson, Marcus Ni, Eduardo Divo, Alain J. Kassab, William Decampli
Patient-Specific Multiscale Computational Fluid Dynamics Assessment Of Embolization Rates In The Hybrid Norwood: Effects Of Size And Placement Of The Reverse Blalock–Taussig Shunt, Ray Prather, John Seligson, Marcus Ni, Eduardo Divo, Alain J. Kassab, William Decampli
Publications
The hybrid Norwood operation is performed to treat hypoplastic left heart syndrome. Distal arch obstruction may compromise flow to the brain. In a variant of this procedure, a synthetic graft (reverse Blalock–Taussig shunt) is placed between the pulmonary trunk and innominate artery to improve upper torso blood flow. Thrombi originating in the graft may embolize to the brain. In this study, we used computational fluid dynamics and particle tracking to investigate the patterns of particle embolization as a function of the anatomic position of the reverse Blalock–Taussig shunt. The degree of distal arch obstruction and position of particle origin influence …
Godunov-Type Upwind Flux Schemes Of The Two-Dimensional Finite Volume Discrete Boltzmann Method, Leitao Chen, Laura Schaefer
Godunov-Type Upwind Flux Schemes Of The Two-Dimensional Finite Volume Discrete Boltzmann Method, Leitao Chen, Laura Schaefer
Publications
A simple unified Godunov-type upwind approach that does not need Riemann solvers for the flux calculation is developed for the finite volume discrete Boltzmann method (FVDBM) on an unstructured cell-centered triangular mesh. With piecewise-constant (PC), piecewise-linear (PL) and piecewise-parabolic (PP) reconstructions, three Godunov-type upwind flux schemes with different orders of accuracy are subsequently derived. After developing both a semi-implicit time marching scheme tailored for the developed flux schemes, and a versatile boundary treatment that is compatible with all of the flux schemes presented in this paper, numerical tests are conducted on spatial accuracy for several single-phase flow problems. Four major …
The Role Of Surface Vorticity During Unsteady Separation, Matthew Scott Melius, Karen Mulleners, Raul Bayoan Cal
The Role Of Surface Vorticity During Unsteady Separation, Matthew Scott Melius, Karen Mulleners, Raul Bayoan Cal
Mechanical and Materials Engineering Faculty Publications and Presentations
Unsteady flow separation in rotationally augmented flow fields plays a significant role in a variety of fundamental flows. Through the use of time-resolved particle image velocimetry, vorticity accumulation and vortex shedding during unsteady separation over a three-dimensional airfoil are examined. The results of the study describe the critical role of surface vorticity accumulation during unsteady separation and reattachment. Through evaluation of the unsteady characteristics of the shear layer, it is demonstrated that the buildup and shedding of surface vorticity directly influence the dynamic changes of the separation point location. The quantitative characterization of surface vorticity and shear layer stability enables …
An Asymptotic Analysis For Generation Of Unsteady Surface Waves On Deep Water By Turbulence, Shahrdad Sajjadi
An Asymptotic Analysis For Generation Of Unsteady Surface Waves On Deep Water By Turbulence, Shahrdad Sajjadi
Publications
The detailed mathematical study of the recent paper by Sajjadi, Hunt and Drullion (2014) is presented. The mathematical developement considered by them, for unsteady growing monochromatic waves is also extended to Stokes waves. The present contribution also demonstrates agreement with the pioneering work of Belcher and Hunt (1993) which is valid in the limit of the complex part of the wave phase speed ci ↓ 0. It is further shown that the energy-transfer parameter and the surface shear stress for a Stokes wave reverts to a monochromatic wave when the second harmonic is excluded. Furthermore, the present theory can …
Experimental Examination Of Vorticity Stripping From A Wing-Tip Vortex In Free-Stream Turbulence, Hari C. Ghimire, Sean C. C. Bailey
Experimental Examination Of Vorticity Stripping From A Wing-Tip Vortex In Free-Stream Turbulence, Hari C. Ghimire, Sean C. C. Bailey
Mechanical Engineering Faculty Publications
Time-resolved stereoscopic particle image velocimetry measurements were conducted of a wing-tip vortex decaying in free-stream turbulence. The objective of the research was to experimentally investigate the mechanism causing the increased rate of decay of the vortex in the presence of turbulence. It was observed that the circulation of the vortex core experienced periods of rapid loss and recovery when immersed in free-stream turbulence. These events were not observed when the vortex was in a laminar free stream. A connection was made between these events and distortion of the vortex, coinciding with stripping of core fluid from the vortex core. Specifically, …
Fermi Questions, Question 1: Air Pressure On Waves; Question 2: Weight Of Toner, Larry Weinstein
Fermi Questions, Question 1: Air Pressure On Waves; Question 2: Weight Of Toner, Larry Weinstein
Physics Faculty Publications
The article presents questions on the difference in air pressure at the crest and trough of ocean waves because of the Bernoulli effect and the difference in weight between a 100-page printed document and 100 blank pages.
Solutions For Fermi Questions, March 2018: Question 1: Air Pressure On Waves; Question 2: Weight Of Toner, Larry Weinstein
Solutions For Fermi Questions, March 2018: Question 1: Air Pressure On Waves; Question 2: Weight Of Toner, Larry Weinstein
Physics Faculty Publications
The article presents questions on the difference in air pressure at the crest and trough of ocean waves because of the Bernoulli effect and the difference in weight between a 100-page printed document and 100 blank pages.
Electroosmotic Flow Of Viscoelastic Fluid In A Nanoslit, Lanju Mei, Hongna Zhang, Hongxia Meng, Shizhi Qian
Electroosmotic Flow Of Viscoelastic Fluid In A Nanoslit, Lanju Mei, Hongna Zhang, Hongxia Meng, Shizhi Qian
Mechanical & Aerospace Engineering Faculty Publications
The electroosmotic flow (EOF) of viscoelastic fluid in a long nanoslit is numerically studied to investigate the rheological property effect of Linear Phan-Thien-Tanner (LPTT) fluid on the fully developed EOF. The non-linear Poisson-Nernst-Planck equations governing the electric potential and the ionic concentration distribution within the channel are adopted to take into account the effect of the electrical double layer (EDL), including the EDL overlap. When the EDL is not overlapped, the velocity profiles for both Newtonian and viscoelastic fluids are plug-like and increase sharply near the charged wall. The velocity profile resembles that of pressure-driven flow when the EDL is …
Analyzing The Spectral Energy Cascade In Turbulent Channel Flow, João Rodrigo Andrade, Ramon Silva Martins, Gilmar Mompean, Laurent Thais, Thomas B. Gatski
Analyzing The Spectral Energy Cascade In Turbulent Channel Flow, João Rodrigo Andrade, Ramon Silva Martins, Gilmar Mompean, Laurent Thais, Thomas B. Gatski
CCPO Publications
An analysis of the spectral turbulent kinetic energy budget in a fully developed turbulent plane channel flow is performed. Direct numerical simulation data are evaluated at friction Reynolds numbers Reτ of 180 and 1000. The analysis is focused on the influence of the Reynolds number on the spectral cascade of energy and the corresponding energy cascade in physical space in the presence of inhomogeneity and anisotropy. The turbulent kinetic energy distribution is compared for both Reynolds numbers, and the relevant characteristics of the energy transfer process in a wall-bounded turbulent flow are described. Differences in energy cascade are noted …
Production And Correlation Of Reactive Oxygen And Nitrogen Species In Gas- And Liquid-Phase Generated By Helium Plasma Jets Under Different Pulse Widths, Zhijie Liu, Chunxi Zhou, Dingxin Liu, Dehui Xu, Wenjie Xia, Qingjie Cui, Bingchuan Wang, Michael G. Kong
Production And Correlation Of Reactive Oxygen And Nitrogen Species In Gas- And Liquid-Phase Generated By Helium Plasma Jets Under Different Pulse Widths, Zhijie Liu, Chunxi Zhou, Dingxin Liu, Dehui Xu, Wenjie Xia, Qingjie Cui, Bingchuan Wang, Michael G. Kong
Bioelectrics Publications
In this paper, we present the effects of the pulse width (PW) on the plasma jet's discharge characteristics, particularly focusing on the production and correlation of the reactive oxygen and nitrogen species (RONS) in gas- and liquid-phase. It is found that the length of plasma jet plume first increases before the PW of 10 μs, then gradually decreases and finally almost remains unchanged beyond 150 μs. The plasma bullet disappears after the falling edge of the voltage pulse at low PW, while it terminates far ahead of the falling edge of voltage pulse at high PW. This is …
Comparison Between The Water Activation Effects By Pulsed And Sinusoidal Helium Plasma Jets, Han Xu, Dingxin Liu, Wenjie Xia, Chen Chen, Weitao Wang, Zhijie Liu, Xiaohua Wang, Michael G. Kong
Comparison Between The Water Activation Effects By Pulsed And Sinusoidal Helium Plasma Jets, Han Xu, Dingxin Liu, Wenjie Xia, Chen Chen, Weitao Wang, Zhijie Liu, Xiaohua Wang, Michael G. Kong
Bioelectrics Publications
Comparisons between pulsed and sinusoidal plasma jets have been extensively reported for the discharge characteristics and gaseous reactive species, but rarely for the aqueous reactive species in water solutions treated by the two types of plasma jets. This motivates us to compare the concentrations of aqueous reactive species induced by a pulsed and a sinusoidal plasma jet, since it is widely reported that these aqueous reactive species play a crucial role in various plasma biomedical applications. Experimental results show that the aqueous H2O2, OH/O2−, and O2−/ONOO− induced by the …
Fluid-Dynamic Models Of Geophysical Waves, Alan Compelli
Fluid-Dynamic Models Of Geophysical Waves, Alan Compelli
Doctoral
Geophysical waves are waves that are found naturally in the Earth's atmosphere and oceans. Internal waves, that is waves that act as an interface between uids of dierent density, are examples of geophysical waves. A uid system with a at bottom, at surface and internal wave is initially considered. The system has a depth-dependent current which mimics a typical ocean set-up and, as it is based on the surface of the rotating Earth, incorporates Coriolis forces. Using well established uid dynamic techniques, the total energy is calculated and used to determine the dynamics of the system using a procedure called …
Numerical Simulation For A Rising Bubble Interacting With A Solid Wall: Impact, Bounce, And Thin Film Dynamics, Changjuan Zhang, Jie Li, Li-Shi Luo, Tiezheng Qian
Numerical Simulation For A Rising Bubble Interacting With A Solid Wall: Impact, Bounce, And Thin Film Dynamics, Changjuan Zhang, Jie Li, Li-Shi Luo, Tiezheng Qian
Mathematics & Statistics Faculty Publications
Using an arbitrary Lagrangian-Eulerian method on an adaptive moving unstructured mesh, we carry out numerical simulations for a rising bubble interacting with a solid wall. Driven by the buoyancy force, the axisymmetric bubble rises in a viscous liquid toward a horizontal wall, with impact on and possible bounce from the wall. First, our simulation is quantitatively validated through a detailed comparison between numerical results and experimental data. We then investigate the bubble dynamics which exhibits four different behaviors depending on the competition among the inertial, viscous, gravitational, and capillary forces. A phase diagram for bubble dynamics has been produced using …
Dynamic Control Of Particle Separation In Deterministic Lateral Displacement Separator With Viscoelastic Fluids, Yuke Li, Hongna Zhang, Yongyao Li, Xiaobin Li, Jian Wu, Shizhi Qian, Fengchen Li
Dynamic Control Of Particle Separation In Deterministic Lateral Displacement Separator With Viscoelastic Fluids, Yuke Li, Hongna Zhang, Yongyao Li, Xiaobin Li, Jian Wu, Shizhi Qian, Fengchen Li
Mechanical & Aerospace Engineering Faculty Publications
We proposed an innovative method to achieve dynamic control of particle separation by employing viscoelastic fluids in deterministic lateral displacement (DLD) arrays. The effects of shear-thinning and elasticity of working fluids on the critical separation size in DLD arrays are investigated. It is observed that each effect can lead to the variation of the critical separation size by approximately 40%. Since the elasticity strength of the fluid is related to the shear rate, the dynamic control can for the first time be easily realized through tuning the flow rate in microchannels.