Physics Commons^™

Rainich-Type Conditions For Perfect Fluid Spacetimes, Dionisios Krongos, Charles G. Torre

Research Vignettes

In this worksheet we describe and illustrate a relatively simple set of new Rainich-type conditions on an n-dimensional spacetime which are necessary and sufficient for it to define a perfect fluid solution of the Einstein field equations. Procedures are provided which implement these Rainich-type conditions and which reconstruct the perfect fluid from the metric. These results provide an example of the idea of geometrization of matter fields in general relativity, which is a purely geometrical characterization of matter fields via the Einstein field equations.

Scaling Group Analysis On Mhd Free Convective Heat And Mass Transfer Over A Stretching Surface With Suction / Injection, Heat Source/Sink Considering Viscous Dissipation And Chemical Reaction Effects, Hunegnaw Dessie, Naikoti Kishan

Applications and Applied Mathematics: An International Journal (AAM)

This paper concerns with scaling group analysis on MHD free convective heat and mass transfer over stretching surface considering effects of thermal-diffusion and diffusion-thermo with suction /injection, heat source/sink and chemical reaction by taking into account viscous dissipation. Scaling group transformations are used to convert the partial differential equations of governing equations into ordinary differential equation and are solved numerically by Keller Box Method. Numerical results obtained for different parameters are drawn graphically and their effects on velocity, temperature and concentration profiles are discussed and shown graphically. Skin-friction coefficient, Nusselt number and Sherwood number are presented in table. It is …

A Novel Approach For Solving Burger’S Equation, Amruta Daga, Vikas Pradhan

Applications and Applied Mathematics: An International Journal (AAM)

The paper presents a new analytical method called Variational Homotopy Perturbation Method (VHPM), which is a combination of the well-known Variational Iteration method (VIM) and the Homotopy Perturbation method (HPM) for solving the one-dimensional Burger’s equation. Two test problems are presented to demontrate the efficiency and the accuracy of the proposed method.The numerical solutions obtained are compared with the exact solution. Furthermore, this method does not require spatial discretization or restrictive assumptions and is free from round-off errors and therefore reduce the numerical computation significanly. The results reveal that the Variational Homotopy Perturbation Method is very effective and convenient to …

Steady Quadratic Stokes Flow Past Deformed Sphere: A Novel Perturbation Technique, Deepak K. Srivastava, Nirmal Srivastava, Raja R. Yadav

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, the problem of steady quadratic Stokes flow past a deformed sphere has been tackled with the use of a novel perturbation technique in both situations when a uniform stream is along the axis of symmetry (axial flow) and when it is perpendicular to the axis of symmetry (transverse flow). The most general form of the deformed sphere, governed by polar equation, is considered here for the study. The general expressions for axial and transverse Stokes drag for deformed sphere has been derived up to the second order of deformation parameter for parabolic and stagnation like parabolic flow. …

Effects Of Radiation Absorption And Thermo-Diffusion On Mhd Heat And Mass Transfer Flow Of A Micro-Polar Fluid In The Presence Of Heat Source, J. I. Oahimire, B. I. Olajuwon

Applications and Applied Mathematics: An International Journal (AAM)

An analysis of the heat and mass transfer effects on an unsteady flow of a micro-polar fluid over an infinite moving permeable plate in a saturated porous medium in the presence of a transverse magnetic field, radiation absorption and thermo-diffusion were studied. The governing system of partial differential equations was transformed to dimensionless equations using suitable dimensionless variables. The dimensionless equations were then solved analytically using perturbation technique to obtain the expressions for the velocity, micro-rotation, temperature and concentration. With the help of graphs, the effects of the various important parameters such as the translational velocity, micro-rotational velocity, temperature and …

Mitigation Of Moving Shocks In An Expanding Duct, Veraun Chipman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inviscid flow theory governs the bulk motion of a gas at some distance away from the walls (i.e. outside the boundary layer). That is to say, there are no viscous forces in the bulk flow, which is modeled using the Euler equations. The Euler equations are simply the Navier-Stokes equations with zero viscosity terms. An ideal inviscid fluid, when brought into contact with a surface or wall, would naturally slip right past it since the fluid has no viscosity. In real life, however, a thin boundary layer forms between the wall or surface and the bulk flow. Shock wave boundary …

Stilling Basin Performance Analysis By Adv, Seyed Sobhan Aleyasin, Nima Fathi, Peter Vorobieff

Nima Fathi

Dynamics Of Skirting Droplets, Caleb Akers, Jacob Hale

Annual Student Research Poster Session

No abstract provided.

Dissipative Superfluid Mass Flux Through Solid 4he, Ye. Vekhov, Robert Hallock

Robert Hallock

The thermomechanical effect in superfluid helium is used to create an initial chemical potential difference ∆u_0 across a solid 4_He sample. This ∆u_0 causes a flow of helium atoms from one reservoir filled with superfluid helium, through a sample cell filled with solid helium, to another superfluid-filled reservoir until potential equilibrium between the reservoirs is restored. The solid helium sample is separated from each of the reservoirs by Vycor rods that allow only the superfluid component to flow. With an improved technique, measurements of the flow F at several fixed solid helium temperatures T have been made as a function …

New Measurements Of Mcmurdo Gravity Wave Parameters, Jonathan Pugmire, Michael J. Taylor

Graduate Student Presentations

The ANtarctic Gravity Wave Instrument Network (ANGWIN) is an NSF sponsored international program designed to develop and utilize a network of gravity wave observatories using existing and new instrumentation operated at several established research stations around the continent. The primary goal is to better understand and quantify large-scale gravity wave climatology and their effects on the upper atmosphere over Antarctica. ANGWIN currently comprises research measurements from five nations (U.S., U.K., Australia, Japan, and Brazil) at seven international stations. Utah State University’s Atmospheric Imaging Lab operates all-sky infrared and CCD imagers and an Advanced Mesospheric Temperature Mapper (AMTM) imager at several …

New Measurements Of Mcmurdo Gravity Wave Parameters, Jonathan R. Pugmire, Michael J. Taylor, P Dominique Pautet

Jonathan Pugmire

The ANtarctic Gravity Wave Instrument Network (ANGWIN) is an NSF sponsored international program designed to develop and utilize a network of gravity wave observatories using existing and new instrumentation operated at several established research stations around the continent. The primary goal is to better understand and quantify large-scale gravity wave climatology and their effects on the upper atmosphere over Antarctica. ANGWIN currently comprises research measurements from five nations (U.S., U.K., Australia, Japan, and Brazil) at seven international stations. Utah State University’s Atmospheric Imaging Lab operates all-sky infrared and CCD imagers and an Advanced Mesospheric Temperature Mapper (AMTM) imager at several …

Particle Swarms In Confining Geometries, Eric Robert Boomsma

Open Access Dissertations

The transport of micro- and nano-particles in subsurface fluid deposits is an area of increasing interest due to the rising use of these particles for consumer and industrial purposes. Subsurface particle transport is complicated by the presence of fractures and fracture networks which govern the paths that particles will be able to take. In this thesis, subsurface particle transport will be investigated using particle swarms; collections of hydro-dynamically interacting particles which exhibit group behavior. The effects of fluid viscosity, particle properties, fracture geometry, and fracture aperture on swarm behavior were experimentally investigated. ^ Swarm parameters were examined in time with …

Gravity Wave Spectra Morphology In The Arctic And Non-Arctic Lower Atmosphere, Melanie C. Wright

Electronic Thesis and Dissertation Repository

The spectral analysis of data from three VHF radars (one high-Arctic and two mid-latitudes) show support for the universal spectrum theory for gravity waves in the lower atmosphere (altitudes of 2.0-11.0 km), provided that the impact of the off-vertical beam and noise are taken into consideration. This analysis also reveals that local gravity wave generation is of secondary importance, but still significant for determining the spectra.

A total of eight spectral methods were considered and scrutinized for the purposes of determining gravity wave spectra from VHF radar data. A definition for the “best” method was given and examined. The method …

Particle Image Velocimetry Of Transverse Jets In Crossflow, Jesse K. Tsai, Kayla Kuzmich, David Forliti, Kriss Vanderhyde, Nils Sedano

STAR Program Research Presentations

The jet in crossflow (JICF) has been an ongoing study for the past several decades with applications in the field of fluid mechanics. This particular flow field produces vortical structures tied to the entrainment and mixing of two separate fluids. Research of the JICF seeks to determine a model and trajectory scaling law for future designs. This will help future designers to optimize the mixing and homogeneity of the two fluids to decrease emissions from pollutants, make ignition easier, and improve combustion efficiency of rockets.

Our experiment will employ Particle Image Velocimetry (PIV) to determine the fluid motion of the …

Does A Plastron Improve Heat Transfer?, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Superamphiphobic surfaces strongly repel both water and oils. In this work, aluminum coupons are processed by sanding with various grit of sand paper to impart microscale roughness. Subsequent submersion of the aluminum substrate in boiling water grows nanoscale grass-like structures. The oxide layer of Al is slightly soluble in water. During a fast diffusion/equilibrium, Al₂O₃ nanograss grows on the surface. A low energy coating is then deposited on the surface. The micro and nanoscale features create re-entrant structures that trap air enabling contact liquid to be in a Cassie-Baxter state. Superamphiphobicity of the samples were confirmed by …

One-Dimensional Weakly Nonlinear Model Equations For Rossby Waves, David Henry, Rossen Ivanov

Articles

In this study we explore several possibilities for modelling weakly nonlinear Rossby waves in fluid of constant depth, which propagate predominantly in one direction. The model equations obtained include the BBM equation, as well as the integrable KdV and Degasperis-Procesi equations.

Universal Temperature Dependence, Flux Extinction And The Role Of 3he Impurities In Superfluid Mass Transport Through Solid 4he, Ye. Vekhov, W. J. Mullin, Robert B. Hallock

Robert Hallock

The mass flux, F, carried by as-grown solid 4_He in the range 25.6-26.3 bar rises with falling temperature, and at a concentration-dependent temperature, T_d, the flux decreases sharply within a few mK. We study F as a function of 3_He impurity concentration, χ. We find that T_(d )is an increasing function of increasing χ. At temperatures above T_d the flux has a universal temperature dependence and the flux terminates in a narrow window near a characteristic temperature T_h ≈ 625 mK, which is independent of χ.

Study Of A Generalized Empirical Model For Predicting Pressure Drop For Internal Flows, Tejas Anup Pant

Open Access Theses

A generalized empirical model for estimating the pressure drop across a channel for a given massflow rate is studied through computational fluid dynamics (CFD) simulations. It is observed that for developing laminar and turbulent flow through channels and pipes of arbitrary cross-section, the variation in the pressure drop between any two points in the flow direction with massflow rate can be well approximated by a second degree expression in massflow rate which is referred to as the empirical model in this study. In the first part of this study, a correlation between the pressure gradient and the massflow rate is …

Viscosity Dependence Of Faraday Wave Formation Thresholds, Lisa M. Slaughter

Symposium

This experiment uses an electromagnetic shaker to produce standing wave patterns on the surface of a vertically oscillating sample of silicon liquid. These surface waves, known as Faraday waves, form shapes such as squares, lines, and hexagons. They are known to be dependent upon the frequency and amplitude of the forcing as well as on the viscosity and depth of the liquid in the dish. At a depth of 4mm and for various silicon liquids having kinematic viscosities of 10, 20, and 38 cSt, we determined the acceleration at which patterns form for frequencies between 10 and 60 Hz. For …

Spontaneous Oscillations In Simple Fluid Networks, Nathaniel Karst, Brian Storey, John Geddes

Brian Storey

Nonlinear phenomena including multiple equilibria and spontaneous oscillations are common in fluid networks containing either multiple phases or constituents. In many systems, such behavior might be attributed to the complicated geometry of the network, the complex rheology of the constituent fluids, or, in the case of microvascular blood flow, biological control. In this paper we investigate two examples of a simple three-node fluid network containing two miscible Newtonian fluids of differing viscosities, the first modeling microvascular blood flow and the second modeling stratified laminar flow. We use a combination of analytic and numerical techniques to identify and track saddle-node and …

Spontaneous Oscillations In Simple Fluid Networks, Nathaniel Karst, Brian Storey, John Geddes

John B. Geddes

Nonlinear phenomena including multiple equilibria and spontaneous oscillations are common in fluid networks containing either multiple phases or constituents. In many systems, such behavior might be attributed to the complicated geometry of the network, the complex rheology of the constituent fluids, or, in the case of microvascular blood flow, biological control. In this paper we investigate two examples of a simple three-node fluid network containing two miscible Newtonian fluids of differing viscosities, the first modeling microvascular blood flow and the second modeling stratified laminar flow. We use a combination of analytic and numerical techniques to identify and track saddle-node and …

Laser Doppler Velocimetry: Flow Measurement Using A Digital Micromirror Device, Dawei Kuo

Physics

In this experiment we utilize a Texas Instruments Digital Micromirror Device to impart a phase shift to the beams of a laser Doppler velocimeter. The advantages of this approach include low cost, low power consumption, a precisely known phase-stepping frequency, and the capability of working with a broad range of optical wavelengths. The velocities measured with the set up shown here are of order 1 cm/s.

Effects Of Radiation Absorption And Mass Transfer On The Free Convective Flow Passed A Vertical Flat Plate Through A Porous Medium In An Aligned Magnetic Field, V. Manjulatha, S. V. K. Varma, V. C. C Raju

Applications and Applied Mathematics: An International Journal (AAM)

This article analyses the effects of radiation absorption and mass transfer on the steady free convective flow of a viscous, incompressible and electrically conducting fluid past an infinite vertical flat plate through a porous medium with an aligned magnetic field. Analytical solutions for concentration, temperature, and velocity are obtained by solving the governing equations in two cases namely (i) when the plate is at uniform temperature and concentration and (ii) when the plate is at constant heat and mass flux. Further the rate of mass transfer in terms of the Sherwood number, rate of heat transfer in terms of Nusselt …

Modelling The Flow Of Aqueous Humor In Schlemm’S Canal In The Eye, Ram Avtar, Swati Srivastava, Rashmi Srivastava

Applications and Applied Mathematics: An International Journal (AAM)

A simple mathematical model for the transient flow of aqueous humor in the canal of Schlemm is developed to investigate the acceleration effects of a sudden elevation in the intraocular pressure on the flow characteristics of the aqueous humor in the canal. The model treats a canal segment as a tube of elliptic cross-section. Exact analytical solution to the model is obtained using separation of variables method. The effects of some important model parameters on the maximum and minimum shear stresses exerted on the Schlemm’s canal epithelial cells (wall) by flowing aqueous humor are investigated for the steady-state flow.

Effect Of Slip Condition On Coup Le Stress Fluid Flow In A Channel With Mild Stenosis In The Presence Of Uniform Magnetic Field, Gurju Awgichew, G. Radhakrishnamacharya, B. Shireesha

Applications and Applied Mathematics: An International Journal (AAM)

The s teady flow of an incompressible couple stress fluid in a two dimensional uniform channel with stenosis under the influence of a magnetic field has been investigated. Assuming the stenosis to be mild, the flow equations have been analy tically solved using the slip condition and expressions for the resistance to flow and wall shear stress have been derived. The effects of various parameters on these flow variables have been studied. It is found that the resistance to flow as well as the wall shear stress increase with the height of the stenosis and decrease with the couple stress …

Mathematical Model Of Blood Flow Through A Composite Stenosis In Catheterized Artery With Permeable Wall, Rupesh K. Srivastav

Applications and Applied Mathematics: An International Journal (AAM)

The present mathematical analysis, the study of blood flow through the model of a composite stenosed catheterized artery with permeable wall, has been performed to investigate the blood flow characteristics. The expressions for the blood flow characteristics-the impedance (resistance to flow), the wall shear stress distribution in stenosis region, the shear stress at the throat of the stenosis have been derived. The results obtained are displayed graphically and discussed briefly.

Effects Of Chemical Reaction And Radiation Absorption On Mhd Flow Of Dusty Viscoelastic Fluid, J. Prakash, A. G. Vijaya Kumar, M. Madhavi, S. V. K. Varma

Applications and Applied Mathematics: An International Journal (AAM)

This investigation is undertaken to study the effects of heat source and radiation absorption on unsteady hydro-magnetic heat and mass transfer flow of a dusty viscous incompressible, electrically conducting fluid between two vertical heated, porous, parallel plates in the presence of chemical reaction under the influence of a transverse applied magnetic field. Initially, the channel walls as well as the dusty fluid are assumed to be at the same temperature and the mass is assumed to be present at low level concentration so that it is constant everywhere. It is also assumed that the dusty particles are non-conducting, solid, spherical …

Smarticles: A Method For Identifying And Correcting Instability And Error Caused By Explicit Integration Techniques In Physically Based Simulations, Susan Aileen Marano

Master's Theses

Using an explicit integration method in physically based animations has many advantages including conceptual and computational simplicity, however, it re- quires small time steps to ensure low numerical instability. Simulations with large numbers of individually interacting components such as cloth, hair, and fluid models, are limited by the sections of particles most susceptible to error. This results in the need for smaller time steps than required for the majority of the system. These sections can be diverse and dynamic, quickly changing in size and location based on forces in the system. Identifying and handling these trou- blesome sections could allow …

Generalized Helicity And Beltrami Fields, Roman V. Buniy, Thomas W. Kephart

Mathematics, Physics, and Computer Science Faculty Articles and Research

We propose covariant and non-abelian generalizations of the magnetic helicity and Beltrami equation. The gauge invariance, variational principle, conserved current, energy-momentum tensor and choice of boundary conditions elucidate the subject. In particular, we prove that any extremal of the Yang-Mills action functional 1/4 f(Omega) trF(mu nu) F-mu nu d(4)x subject to the local constraint epsilon(mu nu alpha beta)trF(mu nu)F(alpha beta) = 0 satisfies the covariant non-abelian Beltrami equation.

Turbulence, Climate And Supercomputers, Georgios Matheou

The STEAM Journal

Turbulence is often referred to as the last mystery of classical physics. Although turbulence is ubiquitous and prominent in our daily lives – from the mixing of milk in a cup of coffee to the perpetual motion of the atmosphere and the resulting weather variation – our understanding of this complex phenomenon is comparatively very limited (e.g., Davidson et al., 2011).