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Hypersonic Viscous Flow Over Slender Cones

Description: Note presenting viscous self-induced pressures on 3 degree semivertex angle cones measured over a free-stream Mach number range and viscous-interaction parameter range. Results regarding the experiment, comparison between theory and experiment, and hole-size effect are provided.
Date: September 1958
Creator: Talbot, Lawrence; Koga, Toyoki & Sherman, Pauline M.
Partner: UNT Libraries Government Documents Department
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The Viscosity of Solids

Description: Preface: This bulletin is a second contribution to the general investigation of the physical contents of rocks, the experiments concerning which follow a general plan devised by Mr. Clarence King.
Date: 1891
Creator: Barus, Carl
Partner: UNT Libraries Government Documents Department
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Frequency-dependent viscous flow in channels with fractal rough surfaces

Description: The viscous dynamic permeability of some fractal-like channels is studied. For our particular class of geometries, the ratio of the pore surface area-to-volume tends to {infinity} (but has a finite cutoff), and the universal scaling of the dynamic permeability, k({omega}), needs modification. We performed accurate numerical computations of k({omega}) for channels characterized by deterministic fractal wall surfaces, for a broad range of fractal dimensions. The pertinent scaling model for k({ome… more
Date: May 1, 2010
Creator: Cortis, A. & Berryman, J.G.
Partner: UNT Libraries Government Documents Department
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Deformation mechanisms in crystalline solids and Newtonian viscous behavior

Description: The three principal mechanisms of plastic flow in crystalline solids at elevated temperature are crystal slip, grain boundary sliding, and diffusional flow. All three mechanisms involve the diffusion of atoms as the rate-controlling process, either in the lattice or in the grain boundary. Under the correct conditions of microstructure, temperature, and stress, each mechanism can lead to Newtonian-viscous behavior. That is, the strain rate increases linearly with the applied stress. In the case … more
Date: November 4, 1999
Creator: Ruano, O A; Sherby, O D & Wadsworth, J
Partner: UNT Libraries Government Documents Department
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Simulations of hydrodynamic interactions among immersed particles in stokes flow using a massively parallel computer

Description: In this paper, a massively parallel implementation of the boundary element method to study particle transport in Stokes flow is discussed. The numerical algorithm couples the quasistatic Stokes equations for the fluid with kinematic and equilibrium equations for the particles. The formation and assembly of the discretized boundary element equations is based on the torus-wrap mapping as opposed to the more traditional row- or column-wrap mappings. The equation set is solved using a block Jacobi … more
Date: May 1, 1995
Creator: Ingber, M. S.; Womble, D. E. & Mondy, L. A.
Partner: UNT Libraries Government Documents Department
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Variable High Order Multiblock Overlapping Grid Methods for Mixed Steady and Unsteady Multiscale Viscous Flows

Description: Flows containing steady or nearly steady strong shocks in parts of the flow field, and unsteady turbulence with shocklets on other parts of the flow field are difficult to capture accurately and efficiently employing the same numerical scheme even under the multiblock grid or adaptive grid refinement framework. On one hand, sixth-order or higher shock-capturing methods are appropriate for unsteady turbulence with shocklets. On the other hand, lower order shock-capturing methods are more effecti… more
Date: December 12, 2007
Creator: Sjogreen, B & Yee, H C
Partner: UNT Libraries Government Documents Department
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Nanoscale manipulation of Ge nanowires by ion hammering

Description: Nanowires generated considerable interest as nanoscale interconnects and as active components of both electronic and electromechanical devices. However, in many cases, manipulation and modification of nanowires are required to realize their full potential. It is essential, for instance, to control the orientation and positioning of nanowires in some specific applications. This work demonstrates a simple method to reversibly control the shape and the orientation of Ge nanowires by using ion beam… more
Date: January 1, 2009
Creator: Picraux, Samuel T; Romano, Lucia; Rudawski, Nicholas G; Holzworth, Monta R; Jones, Kevin S & Choi, S G
Partner: UNT Libraries Government Documents Department
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A Tightly Coupled Particle-Fluid Model for DNA-Laden Flows in Complex Microscale Geometries

Description: We present a stable and convergent method for the computation of flows of DNA-laden fluids in microchannels with complex geometry. The numerical strategy combines a ball-rod model representation for polymers tightly coupled with a projection method for incompressible viscous flow. We use Cartesian grid embedded boundary methods to discretize the fluid equations in the presence of complex domain boundaries. A sample calculation is presented showing flow through a packed array microchannel in 2D.
Date: November 18, 2004
Creator: Trebotich, D; Miller, G H; Colella, P; Graves, D T; Martin, D F & Schwartz, P O
Partner: UNT Libraries Government Documents Department
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Retained gas sampler visualization guide

Description: In a series of experiments performed in Phase II of the retained gas sampler visualization task, the effect of sampler tip geometry on waste sampling process has been investigated. From flow visualizations, which were captured on video, it is clear that disturbances on the surrounding fluid and the fluid entering the sampler were reduced as the tip changed from a flat to a sharper truncated cone shape. It has been shown, throughout this report, that deformation and disturbance of the waste is d… more
Date: September 1, 1994
Creator: Shekarriz, A.
Partner: UNT Libraries Government Documents Department
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Time-Accurate Computation of Viscous Flow Around Deforming Bodies Using Overset Grids

Description: Dynamically evolving boundaries and deforming bodies interacting with a flow are commonly encountered in fluid dynamics. However, the numerical simulation of flows with dynamic boundaries is difficult with current methods. We propose a new method for studying such problems. The key idea is to use the overset grid method with a thin, body-fitted grid near the deforming boundary, while using fixed Cartesian grids to cover most of the computational domain. Our approach combines the strengths of ea… more
Date: April 2, 2001
Creator: Fast, P & Henshaw, W D
Partner: UNT Libraries Government Documents Department
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A 2-D Pore-Network Model of the Drying of Single-Component Liquids in Porous Media

Description: The drying of liquid-saturated porous media is typically approaching using macroscopic continuum models involving phenomenological coefficients. Insight on these coefficients can be obtained by a more fundamental study at the pore- and pore-network levels. In this report, a model based on pore-network representation of porous media that accounts for various process at the pore-scale is presented. These include mass transfer by advection and diffusion in the gas phase, viscous flow in liquid and… more
Date: January 20, 2000
Creator: Yortsos, Yanic C.; Yiotis, A. G.; Stubos, A. K. & Boundovis, A. G.
Partner: UNT Libraries Government Documents Department
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Acoustic Wave Equations for a Linear Viscous Fluid and An Ideal Fluid

Description: The mathematical description of acoustic wave propagation within a time- and space-varying, and moving, linear viscous fluid is formulated as a system of coupled linear equations. This system is rigorously developed from fundamental principles of continuum mechanics (conservation of mass, balance of linear and angular momentum, balance of entropy) and various constitutive relations (for stress, entropy production, and entropy conduction) by linearizing all expressions with respect to the small-… more
Date: July 1, 2002
Creator: ALDRIDGE, DAVID F.
Partner: UNT Libraries Government Documents Department
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Mathematical Modeling of Charged Liquid Droplets: Numerical Simulation and Stability Analysis

Description: The goal of this thesis is to study of the evolution of 3D electrically charged liquid droplets of fluid evolving under the influence of surface tension and electrostatic forces. In the first part of the thesis, an appropriate mathematical model of the problem is introduced and the linear stability analysis is developed by perturbing a sphere with spherical harmonics. In the second part, the numerical solution of the problem is described with the use of the boundary elements method (BEM) on a… more
Date: May 2006
Creator: Vantzos, Orestis
Partner: UNT Libraries
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Nonstandard Analysis and Shock Wave Jump Conditions in a One-Dimensional Compressible Gas

Description: Nonstandard analysis is a relatively new area of mathematics in which infinitesimal numbers can be defined and manipulated rigorously like real numbers. This report presents a fairly comprehensive tutorial on nonstandard analysis for physicists and engineers with many examples applicable to generalized functions. To demonstrate the power of the subject, the problem of shock wave jump conditions is studied for a one-dimensional compressible gas. It is assumed that the shock thickness occurs on a… more
Date: May 25, 2007
Creator: Roy S. Baty, F. Farassat, John A. Hargreaves
Partner: UNT Libraries Government Documents Department
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GILA User's Manual

Description: GILA is a finite element code that has been developed specifically to attack the class of transient, incompressible, viscous, fluid dynamics problems that are predominant in the world that surrounds us. The purpose for this document is to provide sufficient information for an experienced analyst to use GILA in an effective way. The GILA User's Manual presents a technical outline of the governing equations for time-dependent incompressible flow, and the explicit and semi-implicit projection meth… more
Date: June 1, 2003
Creator: CHRISTON, MARK A.
Partner: UNT Libraries Government Documents Department
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Melt fracture revisited

Description: In a previous paper the author and Demay advanced a model to explain the melt fracture instability observed when molten linear polymer melts are extruded in a capillary rheometer operating under the controlled condition that the inlet flow rate was held constant. The model postulated that the melts were a slightly compressible viscous fluid and allowed for slipping of the melt at the wall. The novel feature of that model was the use of an empirical switch law which governed the amount of wall s… more
Date: July 16, 2003
Creator: Greenberg, J. M.
Partner: UNT Libraries Government Documents Department
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Residual stresses in Mo/Si and Mo2C/Si multilayers

Description: The authors report a study of the residual stresses and residual stress relaxation in Mo/Si and Mo{sub 2}C/Si EUV multilayers. The multilayers were fabricated by magnetron sputter deposition, and stress measured using the substrate curvature laser scanning technique. It was found that Mo{sub 2}C/Si multilayers exhibit higher compressive stress than Mo/Si of comparable period and layer thickness ratio. the multilayers sputtered at 0.5 mT Ar pressure have higher compressive stress than those sput… more
Date: April 1, 1999
Creator: Barbee, T. W. & Nguyen, T. D.
Partner: UNT Libraries Government Documents Department
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Interfacial Dynamics of Abelian Domains: Differential Geometric Methods

Description: The equation: ReF`(T,Z)ZF`(T,Z) = 1 for conformal maps f(t,z) is important in interfacial dynamics. We extend the results by Gustafsson on existence and uniqueness of solutions of this equation from the case when f(t,z) is a rational function of z to the case when the spatial derivative f`(t,z) is rational.
Date: December 1997
Creator: Owczarek, Robert M. & Makaruk, Hanna E.
Partner: UNT Libraries Government Documents Department
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A Cell-Centered Adaptive Projection Method for the IncompressibleNavier-Stokes Equations in Three Dimensions

Description: We present a method for computing incompressible viscousflows in three dimensions using block-structured local refinement in bothspace and time. This method uses a projection formulation based on acell-centered approximate projection, combined with the systematic use ofmultilevel elliptic solvers to compute increments in the solutiongenerated at boundaries between refinement levels due to refinement intime. We use an L_0-stable second-order semi-implicit scheme to evaluatethe viscous terms. Res… more
Date: September 25, 2007
Creator: Martin, D.F.; Colella, P. & Graves, D.T.
Partner: UNT Libraries Government Documents Department
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An analysis of lift forces on aerosols in a wall bounded turbulent shear flow

Description: This paper describes work that will lead to a better understanding of the role of lift forces in the deposition of aerosols on the walls bounding a turbulent shear flow. After providing some background information about aerosol trajectories that has been obtained from computer simulations, new results for the lift force in the relevant parameter ranges are presented.
Date: December 31, 1992
Creator: Cherukat, P. & McLaughlin, J. B.
Partner: UNT Libraries Government Documents Department
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Simulations of non-uniform embossing:the effect of asymmetric neighbor cavities on polymer flow during nanoimprint lithography.

Description: This paper presents continuum simulations of viscous polymer flow during nanoimprint lithography (NIL) for embossing tools having irregular spacings and sizes. Simulations varied non-uniform embossing tool geometry to distinguish geometric quantities governing cavity filling order, polymer peak deformation, and global mold filling times. A characteristic NIL velocity predicts cavity filling order. In general, small cavities fill more quickly than large cavities, while cavity spacing modulates p… more
Date: August 1, 2007
Creator: Schunk, Peter Randall; King, William P. (Georgia Institute of Technology, Atlanta, GA); Sun, Amy Cha-Tien & Rowland, Harry D. (Georgia Institute of Technology, Atlanta, GA)
Partner: UNT Libraries Government Documents Department
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Modeling Complex Biological Flows in Multi-Scale Systems using the APDEC Framework

Description: We have developed advanced numerical algorithms to model biological fluids in multiscale flow environments using the software framework developed under the SciDAC APDEC ISIC. The foundation of our computational effort is an approach for modeling DNA-laden fluids as ''bead-rod'' polymers whose dynamics are fully coupled to an incompressible viscous solvent. The method is capable of modeling short range forces and interactions between particles using soft potentials and rigid constraints. Our met… more
Date: June 24, 2006
Creator: Trebotich, D
Partner: UNT Libraries Government Documents Department
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A Numerical Algorithm for Complex Biological Flow in Irregular Microdevice Geometries

Description: We present a numerical algorithm to simulate non-Newtonian flow in complex microdevice components. The model consists of continuum viscoelastic incompressible flow in irregular microscale geometries. Our numerical approach is the projection method of Bell, Colella and Glaz (BCG) to impose the incompressibility constraint coupled with the polymeric stress splitting discretization of Trebotich, Colella and Miller (TCM). In this approach we exploit the hyperbolic structure of the equations of moti… more
Date: December 15, 2003
Creator: Nonaka, A; Miller, G H; Marshall, T; Liepmann, D; Gulati, S; Trebotich, D et al.
Partner: UNT Libraries Government Documents Department
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