Physics Commons^™

An Evaluation Of A Taylor-Galerkin Algorithm For High Speed Inviscid Flows Using Quadrilateral And Triangular Elements, Kim S. Bey

Mechanical & Aerospace Engineering Theses & Dissertations

The Taylor-Galerkin finite element algorithm is used to obtain solutions to the two-dimensional compressible Euler equations. The mathematical formulation of the algorithm is presented for a typical scalar equation. The derivation results in element equations which are assembled over the entire solution domain to obtain the system of equations that are solved explicitly. The algorithm has the unique feature that the finite element matrices can be evaluated in closed form, avoiding expensive numerical integration. Aspects of vector programming strategies and mesh generation important to an effective analysis procedure are also described. Solutions to supersonic flow problems with exact solutions are …

On The Existence Of Periodic And Eventually Periodic Solutions Of A Fluid Dynamic Forced Harmonic Oscillator, Charlie H. Cooke

Mathematics & Statistics Faculty Publications

For certain flow regimes, the nonlinear differential equation Y¨=F(Y)−G, Y≥0, G>0 and constant, models qualitatively the behaviour of a forced, fluid dynamic, harmonic oscillator which has been a popular department store attraction. The device consists of a ball oscillating suspended in the vertical jet from a household fan. From the postulated form of the model, we determine sets of attraction and exploit symmetry properties of the system to show that all solutions are either initially periodic, with the ball never striking the fan, or else eventually approach a periodic limit cycle, after a sufficient number of bounces away from …

A Study Of Integral Equations For Computing Radial Distribution Functions, Zainuriah Hassan

Masters Theses

Integral equation T (a two parameter equation of the Ornstein-Zernike form) is studied for computing the radial distribution functions of simple classical fluids interacting pairwise according to the Lennard-Jones 6-12 potential function. Numerical calculations are done on a computer for the system in the gas and liquid phases. At a high temperature, equation T results are found to agree very well with equation C when the parameters are chosen in a similar way. At a temperature slightly above the critical temperature, results from other sources over a wide density range. In equation T, by varying two of the parameters, the …

Minimal Norm Constrained Interpolation, Larry Dean Irvine

Mathematics & Statistics Theses & Dissertations

In computational fluid dynamics and in CAD/CAM a physical boundary, usually known only discreetly (say, from a set of measurements), must often be approximated. An acceptable approximation must, of course, preserve the salient features of the data (convexity, concavity, etc.) In this dissertation we compute a smooth interpolant which is locally convex where the data are locally convex and is locally concave where the data are locally concave.

Such an interpolant is found by posing and solving a minimization problem. The solution is a piecewise cubic polynomial. We actually solve this problem indirectly by using the Peano kernel theorem to …

A Study Of Integral Equations For Computing Radial Distribution Functions, Robert C. Scherzer

Masters Theses

The use of integral equations to find radial distribution functions for computing thermodynamic properties is examined. The system considered is a simple classical fluid with interactions according to the Lennard-Jones (6-12) pair potential function. Two parametric integral equations (C and T) are studied in detail. Derivation of equation T and a power series solution are given. Computer solutions at several different temperatures, densities, and parameter values are obtained. Comparisons are made betv/een these results and results from integral equation N, PY, and HNC, and results from Monte Carlo, molecular dynamics, and power series methods. Equations C and N are found …

Implementation Of Uniform Perturbation Method For Potential Flow Past Axisymmetric And Two-Dimensional Bodies, Tin Chee Wong

Mechanical & Aerospace Engineering Theses & Dissertations

The aerodynamic characteristics of potential flow past an axisymmetric slender body and a thin airfoil are calculated by using a uniform perturbation analysis method. The method is based on the superposition of potentials of point singularities distributed inside the body. The strength distribution satisfies a linear integral equation by enforcing the flow tangency condition on the surface of the body. The complete uniform asymptotic expansion of its solution is obtained with respect to the slenderness ratio by modifying and adapting an existing technique. Results calculated by the perturbation analysis method are compared with the existing surface-singularity-panel method and some available …

The Development Of A Microprocessor Controlled Linearly Actuated Valve Assembly, Raymond H. Wall

Mechanical & Aerospace Engineering Theses & Dissertations

The development of a proportional fluid control valve/assembly is presented. This electro-mechanical system is needed for space applications to replace the current proportional flow controllers that use bulky hydraulic or pneumatic actuation systems. The flow is controlled by a microprocessor system that monitors the control parameters of upstream pressure and requested volumetric flow rate. The microprocessor achieves the ·proper valve stem displacement by means of a digital linear actuator. A linear displacement sensor is used to measure the valve stem position. 'Ibis displacement is monitored by the microprocessor system as a feedback signal to close the control loop. With an …

Probability Densities And The Random Variable Transformation Theorem, John D. Ramshaw

Physics Faculty Publications and Presentations

D. T. Gillespie has recently derived and discussed a random variable transformation (RVT) theorem relating the joint probability densities of functionally dependent sets of random variables.....

It is hoped that the present discussion will help to disseminate this basic relation among a wider circle of nonspecialists.

Collision-Induced Bands Of Lithium-Rare Gas Molecules, Wen Jong Wang

Physics Theses & Dissertations

Lithium vapor is optically excited by two-step laser excitation of the 3d state in the presence of the rare gases He, Ne, Ar, Kr, and Xe. Collision induced bands are observed in Li-Ar, Li-Kr, and Li-Xe mixtures. The bands are believed to be due to transitions to the dissociating 2s~ ground state from states above the 2p state of the Li-RG molecules. The Li-Ar, Li-Kr, and Li-Xe 3sб -2sб collision induced bands are progressively shifted, for the heavier rare gases, further to the red of the asymptotic atomic Li 3s-2s energy difference. A qualitative comparison is made between the spectra …

Transient Two Dimensional Ground-Water Flow: A Comparison Of Computed And Analytical Results, Robert Jan Fennema

Civil & Environmental Engineering Theses & Dissertations

The exact analytical solution of the transient-flow equation is compared with the finite difference solution. The finite difference program, written by the author, uses an iterative alternating direction implicit procedure to solve the linearized partial differential equation. A second order accurate central difference method is employed to solve the equation in two dimensions.

Variable cell spacing to divide the physical domain, a weighting factor and a time acceleration function were used to investigate rate of convergence and accuracy of the numerical solution. The exact integral solution to the one-dimensional form of the flow equation i n radial coordinates is used …

Application Of The Method Of Lines For Solutions Of The Navier-Stokes Equations Using A Nonuniform Grid Distribution, Jamshid Samareh Abolhassani

Mechanical & Aerospace Engineering Theses & Dissertations

The feasibility of the method of lines is investigated for solutions of physical problems requiring nonuniform grid distributions. To attain this, it was also necessary to investigate the stiffness characteristics of the pertinent equations. For specific applications, the governing equations considered are those for viscous, incompressible, two-dimensional and axisymmetric flows. These equations are transform­ ed from the physical domain having a variable mesh to a computational domain with a uniform mesh. The two governing partial differential equations are the vorticity and stream function equations. The method of lines is used to solve the vorticity equation and the successive over relaxation …

Experimental Investigation Of A Rectangular Surface Thermal Plume, Li-Cheng Chu

Mechanical & Aerospace Engineering Theses & Dissertations

An experimental investigation of the three dimensional mean temperature distribution of a rectangular buoyant surface thermal plume has been conducted for a range of buoyancies, velocity ratios, Reynolds numbers, and for various turbulence generating screens in the crossflow. This study has been motivated by a concern about the applicability of laboratory model data for predicting prototype plume behavior.

A large scale model has been built to study a buoyant, rectangular surface thermal plume which enters at right angles to a constant temperature uniform crossflow of depth equal to that of the plume. A large water tank and flume with weir …

Influence Of Las Vegas Wash Density Current On Nutrient Availability And Phytoplankton Growth In Lake Mead, John R. Baker, Larry J. Paulson

Publications (WR)

Density currents are commonly formed in reservoirs because of temperature or salinity induced density differences between inflowing and receiving waters. Anderson and Pritchard (1951) were among the first to demonstrate this in their investigations of density currents in Lake Mead. They found that the Colorado River formed an underflow in Lake Mead during the winter, an overflow in the spring and an interflow in the summer and fall. Wunderlich and Elder (1973) have since described the hydromechanics of these types of flow patterns, and density currents have been reported for several other large reservoirs (Carmack et al. 1979, Johnson and …

Partial Chemical Equilibrium In Fluid Dynamics, John D. Ramshaw

Physics Faculty Publications and Presentations

An analysis is given for the flow of a multicomponent fluid in which an arbitrary number of chemical reactions may occur, some of which are in equilibrium while the others proceed kinetically. The primitive equations describing this situation are inconvenient to use because the progress rates ω [subscript s] for the equilibrium reactions are determined implicitly by the associated equilibrium constraint conditions. Two alternative equivalent equation systems that are more pleasant to deal with are derived. In the first system, the ω [subscript s] are eliminated by replacing the transport equations for the chemical species involved in the equilibrium reactions …

Effect Of Compliant Wall Motion On Turbulent Boundary Layers, Dennis M. Bushness, Jerry N. Hefner, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

A critical analysis of available compliant wall data which indicated drag reduction under turbulent boundary layers is presented. Detailed structural dynamic calculations suggest that the surfaces responded in a resonant, rather than a compliant, manner. Alternate explanations are given for drag reductions observed in two classes of experiments: (1) flexible pipe flows and (2) water-backed membranes in air. Analysis indicates that the wall motion for the remaining data is typified by short wavelengths in agreement with the requirements of a possible compliant wall drag reduction mechanism recently suggested by Langley. Copyright © 1977 American Institute of Physics.

Fluid Mechanics In The Elementary Laboratory, James C. Dennis

Faculty Publications

No abstract provided.

An Experimental And Theoretical Study Of The Flow Phenomena Within A Vortex Sink Rate Sensor, Dashrath Khodidas Patel

Mechanical & Aerospace Engineering Theses & Dissertations

The objective of this investigation was to obtain a detailed description of the flow field within a vortex sink rate sensor and to observe the influence of viscous effects on its performance.

The sensor basically consists of a vortex chamber and a sink tube. The vortex chamber consists of two circular coaxial disks held apart, at their periphery, by a porous coupling. One circular disk has an opening to permit the mounting of the sink tube, in such a manner that the vortex chamber as well as the sink tube have a common axis of rotation.

Air was supplied radially …

Studies Of Bistable Fluid Devices For Particle Flow Control, Gerald H. Hogland

Dissertations and Theses

This study was directed toward the development of a bistable wall attachment Flip-Flop device which was capable of directionally controlling particle flow. The particles were transported by a fluid stream which under the influence of wall attachment. The dominant criteria in the development of the device was the achievement of the highest recovery of particles at the active output, without destroying the wall attachment of the fluid stream The experiment was conducted in several distinct stages; each of which was concerned with at least one aspect of wa1l attachment or particle flow. Results derived from one test were used to …

Measurement Of Currents In Lake Mead With The Deep Water Isotopic Current Analyzer (Dwica), J. J. Sartoris, D. A. Hoffman, Bureau Of Reclamation

Publications (WR)

In Nov 1967, a Deep Water Isotopic Current Analyzer (DWICA) was used to study current patterns in the Boulder Basin of Lake Mead to determine if low-quality water from Las Vegas Bay might enter the Southern Nevada Water Project intake on Saddle Island. Secondary objectives were to study the general current patterns in Boulder Basin and the effect of power discharges at Hoover Dam on these currents. Results of current measurements at 3 stations in Boulder Basin are given. Observations indicate a definite possibility that low-quality water from Las Vegas Bay might enter the water intake on Saddle Island. Current …

An Experimental Investigation Of The Vortex Sink Rate Sensors, Nelson L. Lu

Mechanical & Aerospace Engineering Theses & Dissertations

The vortex sink rate sensor device consists basically of an ideal sink flow between two coaxial disks. A sink tube was located at the center of one disk. The vortex was created by the rotation of the unit about its axis of symmetry. Five inch and 10 inch diameter of porous couplers were used for the air chamber here in this investigation. Several slenderness parameters, i.e., the ratio of the sink tube diameter to the height of the air chamber ^ro/n were conducted. Two probes were used to measure the static pressure and stagnation pressure respectively at various positions …

The 1963-64 Lake Mead Survey, J. M. Lara, J. I. Sanders, Bureau Of Reclamation

Publications (WR)

The 1963-64 Lake Mead survey was run to compute the reservoir capacity. Results of the geodetic and hydrographic surveys and sediment sampling equipment are described. The geodetic survey showed Hoover Dam subsided an average of 118 mm since 1935. Sonic sounding, photogrammetry, and crosssectional profiling methods were used to run the hydrographic survey. Reservoir area and capacity tables were generated using an electronic computer. The present lake capacity is 29,755,000 acre-ft and the reservoir surface area is 162,700 acres at elevation 1229 ft. 2,720,000 acre-ft of sediments accumulated in the lake since 1935. A unit weight of 60 Ib/cu ft …

A Numerical Solution To The Problem Of Rotation Near The Ground, David D. Chen

Mechanical & Aerospace Engineering Theses & Dissertations

No abstract.

Asymptotic Behavior Of Fluid Jets, Ronald Walter Godfrey

All Master's Theses

In this paper we shall consider the steady-state, two dimensional, irrotational flow of an inviscid, incompressible fluid under gravity.

Pumping And Horsepower, R P. Harington

Journal of the Department of Agriculture, Western Australia, Series 4

WATER is vital to the survival of plants and animals and its availability will influence the site of the homestead and the farm layout generally.

This article describes some of the factors involved in the installation of a pumping outfit for domestic and stock requirements.

The Coexistence Of Eight Liquid Phases, Herbert A. Goeden

Bachelors’ Theses

For years chemists have been attempting to produce multiple immiscible liquid phase systems. The author has discovered a system of eight liquid phases in equilibrium. The eighth layer is a silicone oil. In order to utilize the silicone oil it was necessary to change two of the seven phases previously recorded.

The Coexistence Of Eight Liquid Phases, Herbert A. Goeden

Bachelors’ Theses

For years chemists have been attempting to produce multiple immiscible liquid phase systems. The author has discovered a system of eight liquid phases in equilibrium. The eighth layer is a silicone oil. In order to utilize the silicone oil it was necessary to change two of the seven phases previously recorded.