| Optimal Pulse Shapes for SHPB Tests on Soft Materials |
Dec 2011 |
20 pages |
| Authors:
Mike Scheidler; John Fitzpatrick; Reuben Kraft; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
 | For split Hopkinson pressure bar (SHPB) tests on soft materials, the goals of homogeneous deformation and uniform uniaxial stress in the specimen present experimental challenges, particularly at higher strain rates. It has been known for some time that attainment of these conditions is facilitated by reducing the thickness of the specimen or by appropriately shaping the loading pulse. Typically, both methods must be employed. Pulse shapes are often tailored to ... |
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| Laminated Composite Sandwich Plates with a Weak Compressible Core Impacted by Blast Loading |
03 Nov 2011 |
39 pages |
| Authors:
Terry Hause; Sudhakar Arepally; ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
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| The governing theory of asymmetric sandwich plates with a first-order compressible core impacted by a Friedlander-type of blast has been presented and simplified for the case of symmetric cross-ply and single-layered orthotropic facings. In all cases, it was mentioned that all four edges are simply supported and freely movable. Results were then presented for this simplified case and validated against results found in the literature from R. S. Alwar et ... |
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| Analytical Solutions for Predicting Underwater Explosion Gas Bubble Behaviour |
NOV 2010 |
46 pages |
| Authors:
Mark Riley; DEFENCE RESEARCH AND DEVELOPMENT ATLANTIC DARTMOUTH (CANADA)
|
| This study describes different analytical models that have previously been developed for predicting the radial growth and collapse of underwater explosion (UNDEX) gas bubbles in a free-field environment. The report describes the implementation of nine analytical gas bubble models, in the form of nonlinear differential equations, and a fourth-order Runge-Kutta solution method. Gas bubble radius time histories calculated with these models are compared to empirical models derived from published experimental ... |
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| PAR3D: Numerical Model for Incompressible Flow with Application to Aerosol Dispersion in Complex Enclosures |
SEP 2007 |
80 pages |
| Authors:
Robert S. Bernard; Phu V. Luong; Mario J. Sanchez; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
|
| Abstract: This report documents the development of the PAR3D numerical flow model, with emphasis on modifications incorporated to facilitate simulations of contaminant dispersion in complex buildings and other enclosures. PAR3D is a general-purpose computational fluid dynamics (CFD) code for predicting three-dimensional flow and transport in air, water, and other incompressible fluids. It includes a two-equation turbulence model with adjustments for buoyancy, as well as transport equations for suspended materials (contaminants), ... |
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| B and F Projection Methods for Nearly Incompressible Linear and Nonlinear Elasticity and Plasticity using Higher-order NURBS Elements |
AUG 2007 |
62 pages |
| Authors:
T. Elguedj; Y. Bazilevs; V. M. Calo; T. J. Hughes; TEXAS UNIV AT AUSTIN
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| This paper presents projection methods to treat the incompressibility constraint in small and large deformation elasticity and plasticity within the framework of Isogeometric Analysis. After reviewing some fundamentals of isogeometric analysis we investigate the use of higher-order Non-Uniform Rational B-Splines "NURBS" within the B projection method. The higher-continuity property of such functions is explored in nearly incompressible applications and shown to produce accurate and robust results. A new nonlinear F ... |
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| Ultra High Pressure Air Properties and CFD Code |
28 FEB 2007 |
25 pages |
| Authors:
Charles L. Merkle; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
|
| The research objectives are to develop effective procedures for computing fluid flow at ultra high pressures where fluids exhibit very different thermodynamic behavior than the perfect gas and incompressible fluid models that are commonly used in CFD simulations. Three issues to be addressed include: developing RANS algorithms for arbitrary fluid applications; developing efficient properties evaluation procedures for arbitrary fluids; and extending hybrid RANS-LES algorithms to high pressures. All three of ... |
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| Scaling of Water Flows and Obstacle Displacements in Shallow Underwater Explosion Field Tests |
10 FEB 2006 |
37 pages |
| Authors:
William W. McDonald; NAVAL SURFACE WARFARE CENTER INDIAN HEAD DIV MD
|
| This work develops a theory for scaling fluid and underwater obstacle motion caused by shallow explosive charges. The motivation is to be able to replicate full-scale test results in subscale experiments despite the fact that gravity remains the same in both tests. The scaling theory is based on the incompressible Euler equations and results for fluid motion are verified through computational example. The applicability of this scaling to obstacle motion ... |
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| Global Weak Solution of Planetary Geostrophic Equations with Inviscid Geostrophic Balance |
2006 |
13 pages |
| Authors:
Jian-Guo Liu; Roger Samelson; Cheng Wang; OREGON STATE UNIV CORVALLIS COLL OF OCEANIC AND ATMOSPHERIC SCIENCES
|
| A reformulation of the planetary geostrophic equations (PGEs) with inviscid balance equation is proposed and the existence of global weak solutions is established, provided that the mechanical forcing satisfies an integral constraint. There is only one prognostic equation for the temperature field and the velocity field is statically determined by the planetary geostrophic balance combined with the incompressibility condition. Furthermore, the velocity profile can be accurately represented as a functional ... |
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| Quasi-2D Unsteady Flow Procedure for Real Fluids |
02 NOV 2005 |
10 pages |
| Authors:
Bryan Campbell; Roger Davis; AEROJET SACRAMENTO CA
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| Details of the numerical solution techniques, including explicit, point-implicit, and fully implicit schemes, used in a new quasi two-dimensional procedure for the transient solution of real fluids in system lines and volumes are presented. The procedure is coupled with a real-fluid properties database so that both compressible and incompressible fluids may be considered using the same code. The procedure has been implemented in Matlab/Simulink(R) as well as Fortran95 to allow ... |
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| A Unified View of Global Instabilities of Compressible Flow Over Open Cavities |
30 JUN 2005 |
7 pages |
| Authors:
Tim Colonius; Guillaume Bres; CALIFORNIA INST OF TECH PASADENA DIV OF ENGINEERING AND APPLIED SCIENCE
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| We report progress in our ongoing effort to compute and understand the three-dimensional instabilities (resonance) of open cavity flows from incompressible to supersonic speeds. In particular, our work is aimed at regimes where significant interactions occur between the shear layer spanning the cavity and the recirculating flow within the cavity, as encountered in many experiments and numerical simulations reported in the literature. Complementary methodologies for extracting information about global instabilities ... |
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| Frontiers in Applied and Computational Mathematics `05' |
MAR 2005 |
69 pages |
| Authors:
Miura; AIR FORCE OFFICE OF SCIENTIFIC RESEARCH ARLINGTON VA
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| Partial contents: Mathematical Biology-A Newcomer to Applied Mathematics, Scale-Invariant Adaptation , Coupled Cell Systems: Theory and Examples, Effective Scientific Simulations, Simulating Rare Events in Lightware Systems with Importance Sampling, Sound Source Location, Industry-Driven Challenges in Applied Mathematics, Waves of Excitation in Nueral Field Models, Impact of a Solid into a Viscoelastic Micellar Fluid, Shocks in Driven Liquid Films, Modeling Network Interactions Between the Hypothelalamus and Pituitary, Chaotic Desynchronization of Multi-Strain ... |
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| Conceptual Design, Engineering Modeling, and Experimental Validation of Air Sampling System for Chemical Sensor Insertion into the U.S. Army Research Laboratory's (ARL) Silent Operating Aerial Reconnaissance (SOAR) Program |
FEB 2004 |
45 pages |
| Authors:
Michael L. Nair; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The U.S. Army Research Laboratory is interested in using a concept unmanned aerial vehicle (UAV) as a chemical weapons detection platform. This report details a preliminary effort to determine whether the UAV is capable of sustaining the needed air flow into a chemical weapons detector to ensure functionality. For this study, it was decided that a minimum volumetric flow rate of 1.4 liters/minute is required to satisfy the minimum flow ... |
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| Energy-Based Design Methodology for Air Vehicle Systems: Aerodynamic Correlation Study |
2004 |
5 pages |
| Authors:
Richard S. Figliola; CLEMSON UNIV SC
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| This fundamental study served to formulate and predict numerically incompressible airfoil and wing performance in terms entropy generation and develop a useful understanding of its role in design. This work is part of a larger effort to define system-level energy-based design across the spectrum of aircraft size and speed. Work was performed at both AFRL and at Clemson with the intent of developing in-house expertise at AFRL. |
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| Investigating the Three-Dimensional Effect on Crack Growth Behavior in an Incompressible Material |
08 JUL 2003 |
14 pages |
| Authors:
C. T. Liu; C. W. Smith; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| For presentation at the International Conference on Advanced Techniques in Experimental Mechanics in Nagoya, Japan, September 2003. |
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| Prostate Carcinoma Detection Using Combined Ultrasound, Elasticity, and Tissue Strain-Hardening Imaging |
JUL 2003 |
12 pages |
| Authors:
Stanislav Y. Emelianov; MICHIGAN UNIV ANN ARBOR
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| The underlying hypothesis of this study is that remote, non-invasive measurements of elasticity in prostate glands are possible and can provide unique examiner-independent information that can increase the detection and/or characterization of potentially malignant masses in the prostate not accessible to manual palpation. The purpose of this study is to develop ultrasound technology to produce high-resolution displacement and strain data throughout the prostate for remote evaluation of the strain-dependent elastic ... |
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| Advanced Radiation Theory Support Annual Report 2002, Final Report |
01 MAY 2003 |
150 pages |
| Authors:
J. Davis; J. Apruzese; Y. Chong; R. Clark; A. Dasgupta; NAVAL RESEARCH LAB WASHINGTON DC
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| This report describes the work of the Radiation Hydrodynamics Branch during FY 2002 in support of the DTRA PRS Program Critical issues covered are: (1) side-on and end-on x-ray imaging of wire and gas puff implosions, (2) multi- group radiative diffusion, (3) discussions of radiation transport that includes pitfalls inherent to radiation modeling of Z-pinch plasmas, (4) K-shell yield performance assessment of argon loads on DTRA machines, (5) Z-pinch-driven direct ... |
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| Investigating Three-Dimensional Effect on Crack Growth Behavior in an Incompressible Material |
11 FEB 2003 |
9 pages |
| Authors:
C. T. Liu; C. W. Smith; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| In order to obtain some insight into the three-dimensional effects on the crack growth behavior, a series of experiments on centrally perforated cylinders under internal pressure were conducted using the frozen stress methods. The inner surface of the cylinder has a star shape, which consists of six fins. Part-through cracks were cut at different locations near the fin tip region. The effect of crack location on the crack growth behavior ... |
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| MR Elastography System for Breast Cancer Detection |
OCT 2002 |
41 pages |
| Authors:
Robert J. Kline-Schoder; CREARE INC HANOVER NH
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| Early diagnosis of breast cancer, which is critical for favorable clinical outcomes, is difficult because tumors and healthy tissue respond similarly to X rays and ultrasound. One physical property that clearly distinguishes healthy from cancerous tissue is mechanical stiffness or hardness. Researchers have attempted to combine external mechanical stimulation and Magnetic Resonance Imaging (MRI) to quantitatively measure the Young's modulus of tissue throughout both the breast and the prostate. This ... |
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| High Resolution Measurements of Supersonic Shear Flow Mixing and Combustion |
OCT 2001 |
79 pages |
| Authors:
Werner J. Dahm; James F. Driscoll; MICHIGAN UNIV ANN ARBOR DEPT OF AEROSPACE ENGINEERING
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| An experimental investigation of compressibility effects on the large-scale structure scaling laws, and entrainment and mixing rates in supersonic, planar, turbulent, bluff-body wakes was conducted. The compressibility effects in supersonic wakes were found to differ significantly from those in supersonic mixing layers. Results at free stream Mach numbers 2 and 3 showed that the large-scale structure of incompressible turbulent wakes was recovered in supersonic wakes at downstream locations where the ... |
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| A Novel Technique for Percutaneous Vertebroplasty in the Treatment of Metastatically Involved Vertebral Bodies |
SEP 2001 |
18 pages |
| Authors:
Cari M. Whyne; SUNNYBROOK HEALTH SCIENCE CENTER TORONTO (ONTARIO)
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| Metastatic disease to the spine occurs in up to one third of all cancer patients. Over 50% of spinal metastases with neurologic manifestations in females are found to arise from primary breast neoplasms. Percutaneous vertebroplasty is a minimally invasive procedure designed to provide stability to structurally weakened vertebrae due to osteoporosis or lytic lesions. In percutaneous vertebroplasty, clinically significant complications occur predominantly in patients with spinal metastases. We proposed that ... |
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| Description of the Navy Coastal Ocean Model Version 1.0 |
31 DEC 2000 |
45 pages |
| Authors:
Paul J. Martin; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS
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| This report provides a description of the Navy Coastal Ocean Model (NCOM) Version 1.0. The model has a free surface and is based on the primitive equations and the hydrostatic, Boussinesq, and incompressible approximations. The model uses an Arakawa C grid, is leapfrog in time with an Asselin filter to suppress timesplitting, and uses second-order centered spatial finite differences. The propagation of surface waves and vertical diffusion is treated implicitly. ... |
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| Generalized Hydrodynamics with Viscoplasticity for Channeling in Saturated Sand |
22 JUN 2000 |
30 pages |
| Authors:
William G. Szymczak; Joel C. Rogers; NAVAL RESEARCH LAB WASHINGTON DC PHYSICAL ACOUSTICS BRANCH
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| In this report we review the "Generalized Formulation of Hydrodynamics" for a single incompressible species with free surfaces and consider methods to extend this formulation to the multiple species case. Constraints on the species volume fractions are imposed using successive redistribution. Formulations that include material strength and viscosity are described. A non-Newtonian viscous model, which approximates a Bingham plastic model, is described and ... |
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| Stress Intensity Factors for Cracks Within and Near to Bondlines in Soft Incompressible Materials |
16 JUN 2000 |
15 pages |
| Authors:
C. W. Smith; K. T. Gloss; D. M. Constantinescu; C. T. Liu; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| Using a polyurethane photoelastic material, thick test specimens of several configurations with bonded end tabs are examined for measuring stress intensity factors (SIFs) for cracks within and near to bondlines in bonded photoelastic models. Effects of specimen height, glued end tabs, bondline and crack size and location are studied and analyzed using a two parameter model for extracting the SIFs and results are compared with cracked, homogeneous model results. |
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| Fractal Geometry and Growth Rate Changes of Cryogenic Jets Near the Critical Point |
14 JUN 1999 |
16 pages |
| Authors:
B. Chehroudi; D. Talley; E. Coy; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| Injection of several pure fluids into a chamber with different ambient gases under supercritical temperature but sub- to supercritical condition based on the injectant thermodynamic critical conditions resulted in the following: the jet exhibits classical liquid-like jet second wind-induced type breakup until chamber pressure reaches near the critical point of the jet substance beyond which gas-like visual behavior is observed and no drops are found. For the first time, these ... |
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| Modeling of Interfacial Fracture in Photoelastic Specimens |
JUN 1998 |
13 pages |
| Authors:
Timothy C. Miller; SPARTA INC EDWARDS AFB CA
|
| Viewgraphs of presentation given on the modeling of interfacial fracture in photoelastic specimens. |
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| Large Eddy and Unstructured Grid Methods for Heat Transfer Applications in Propulsion Systems |
20 MAY 1998 |
34 pages |
| Authors:
Richard H. Pletcher; IOWA STATE UNIV AMES DEPT OF MECHANICAL ENGINEERING
|
| Large eddy simulation methods have been developed to compute compressible turbulent flows with heat transfer. The formulation employs preconditioning to permit efficient use in the low Mach number regime. Efficient algorithms have been developed for both vector and parallel processing computer systems. Simulation results have been obtained using a dynamic subgrid-scale model for a channel heated and cooled at temperature ratios as high as 3. Results were also obtained for ... |
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| Model Validations and Predictions for Water Barrier Defense |
12 MAY 1998 |
38 pages |
| Authors:
William G. Szymczak; Charles E. Higdon; NAVAL RESEARCH LAB WASHINGTON DC PHYSICAL ACOUSTICS BRANCH
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| Validations of a mathematic model and computational code for predicting shallow-depth explosion plume behavior are presented. The model is based on a generalized formulation of hydrodynamics and uses an incompressible liquid assumption. This formulation is well suited for predicting long-time bubble and plume dynamics. Initial conditions for the model are derived from spherically symmetric bubble theory, combined with empirical measurements. The effect of "fingering" of plumes occurring at the center ... |
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| Mode Mixity Determinations for Interfacial Cracking in Incompressible Materials Under Plane Strain Conditions |
22 APR 1998 |
8 pages |
| Authors:
Timothy C. Miller; SPARTA INC EDWARDS AFB CA
|
| When a crack experiences plane strain conditions and lies along the interface between incompressible materials, the near tip field equations are simplified by the vanishing of the bimaterial parameter, epsilon. Finite element models that use a mixed formulation can be used to characterize the complex stress intensity factor of these cracks completely. This is done by using J integral calculations and a regression of the ratio of bond line traction ... |
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| High Order Numerical Methods for Discontinuous or High Gradient Problems |
09 MAR 1998 |
10 pages |
| Authors:
Chi-Wang Shu; BROWN UNIV PROVIDENCE RI DIV OF APPLIED MATHEMATICS
|
| This project is about the design, analysis and application of high order accurate and nonlinearly stable finite difference (including finite volume), finite element and spectral algorithms for computing solutions of partial differential equations which are either discontinuous or with sharp gradients. Algorithm development, theoretical study about stability and convergence of the algorithms, investigation about efficient implementation including parallel implementations, and applications in compressible and incompressible gas dynamics and in semiconductor ... |
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| Modeling of Interfacial Fracture in Incompressible Materials with Varying Modulus Mismatch |
10 FEB 1998 |
13 pages |
| Authors:
T. C. Miller; SPARTA INC EDWARDS AFB CA
|
| Numerical modeling is used to evaluate the effects of modulus mismatch on interfacial fracture. Different modulus ratios are considered, as are different mode mixities. The magnitudes of the complex stress intensity factors are evaluated using the energy domain integral approach, and the phase angles are measured using extrapolation of bond line traction data to r = 0. The results indicate that moderate changes in the modulus ratio have only a ... |
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| Explosive Channeling in Submerged Soils |
1998 |
5 pages |
| Authors:
W. L. Fourney; D. J. Goodings; Z. S. Abu-Hassanein; MARYLAND UNIV COLLEGE PARK DEPT OF AEROSPACE ENGINEERING
|
| The goal of this task is to develop a methodology by which the geometry of a channel in the surf zone as produced by a line of explosive charges may be predicted. To achieve this goal, an NRL incompressible hydrocode is required which models the excavation by bubble expansion. If necessary, the initial conditions produced by shock wave effects could be provided by a compressible code. This incompressible code would ... |
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| DTIC Information for AFOSR Task 2304CP Lattice-Gas Theory and Computation for Complex Fluid Dynamics |
06 NOV 1997 |
6 pages |
| Authors:
J. Yepez; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
| Aid the Air Force modeling community by developing a "mid-level" approach to simulating the behavior of complex fluids, such as viscous incompressible fluids, hydrothermal fluids, inviscid fluids, multiphase fluids, and superfluids. Traditional approaches to complex fluid simulation include "low-level" molecular dynamics or "high-level" partial differential equation approximation schemes. MD suffers from insufficient spatial and temporal scales. The PDE schemes suffer from numerical instabilities and coarseness in the physical description. Lattice ... |
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| Numerical Simulations of Wall Jets |
10 JUL 97 |
30 pages |
| Authors:
Hermann F. Fasel; ARIZONA UNIV TUCSON DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| This document summarizes the three year investigation of transitional and turbulent wall jets using direct numerical simulation (DNS) and large eddy simulation (LES). Towards this end, a three-dimensional, incompressible Navier- Stokes code developed in our research group for DNS of boundary-layer transition was adapted to the wall jet geometry. The code is based on the spatial model and is fourth-order accurate. For the LES, a Smagorinsky based subgrid-scale turbulence model ... |
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| A Numerical Model for Breaking Waves: The Volume of Fluid Method |
FEB 97 |
56 pages |
| Authors:
Philip L. Liu; Pengzhi Lin; DELAWARE UNIV NEWARK CENTER FOR APPLIED COASTAL RESEARCH
|
| This report reviews a numerical model for calculating the evolution of a breaking wave. The model is the combination of a modified version of RIPPLE which was originally developed at Los Alamos National Laboratory (Kothe et al., 1991) and the kappa - epsilon turbulence model. In the model, finite difference solutions to the incompressible Reynolds equations for the mean flow field and the kappa - epsilon equations for the turbulent ... |
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| Compressible Turbulence Measurement in the Mixing Layer of an Adiabatic Normal Slot Injection into Supersonic Flow |
DEC 95 |
86 pages |
| Authors:
Christopher D. Whitcomb; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| In this study mean flow and compressible turbulence measurements were taken at a station x = 72W downstream of the injection, where W is the injector throat width, of an adiabatic 2-D Mach 1.6 normal slot injection into a Mach 2.9 flow. Data were collected using a conventional Pitot probe, a cone- static probe, and multiple overheat cross-wire anemometry. In addition, schlieren and shadowgraph flow visualization was used to investigate ... |
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| Theoretical Studies on Short-Pulse Ocular Damage |
AUG 95 |
28 pages |
| Authors:
Lihong Wang; ANALYTIC SCIENCES CORP SAN ANTONIO TX
|
| A theoretical analysis has been performed for the phase transitions from liquid to gas on the boundary of a spherical particle, submerged in a fluid such as water or ocular media, that is heated by absorption of sub-nanosecond laser pulses. This analysis was based on the conservation of mass and it utilized the general heat conduction equation for the principle of conservation of energy and the basic hydrodynamic equation for ... |
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| Pressure Updating Methods for the Steady-State Fluid Equations |
MAY 95 |
16 pages |
| Authors:
A. Fiterman; E. Turkel; V. Vatsa; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
|
| We consider the steady state equations for a compressible fluid. Since we wish to solve for a range of speeds we must consider the equations in conservation form. For transonic speeds these equations are of mixed type. Hence, the usual approach is to add time derivatives to the steady state equations and then march these equations in time. One then adds a time derivative of the density to the continuity ... |
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| Evaluation of Techniques for Computer Modeling and Real Time Control of a Horizontal Axis Wind Turbine Blade |
MAY 95 |
25 pages |
| Authors:
Alan Wesenberg; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| Wind power generating turbines operate under constant as well as rapidly changing conditions. With fixed pitch blades, many wind turbines are allowed to operate regardless of wind conditions as long as they are able to produce more electricity than it takes to get them started. However, the lifecycle of the turbine blades is often much shorter than expected because of the unsteady aerodynamic environment under which they rotate. Therefore, the ... |
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| Wavelets and Splines in Numerical Methods and Compression |
15 MAR 95 |
11 pages |
| Authors:
Daniel A. Williams; Louise A. Raphael; HOWARD UNIV WASHINGTON DC DEPT OF MATHEMATICS
|
| There were three major research explorations. (1) Wavelets: Necessary and sufficient conditions on the wavelet, scaling function and projection kernel for given rates of convergence of wavelet expansions in the supremum and L (P) (Rd) norms have been given. (2) Image compression is developed using quasi- interpolant multivariate box splines and multi-resolution analysis has been developed. (3) Shallow Water Theory: A mathematical justification for the "shallow water theory for time-dependent ... |
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| Response of Dual-Layered Structures Subjected to Shock Pressure Wave |
31 DEC 94 |
85 pages |
| Authors:
T. P. Brasek; Y. W. Kwon; Y. S. Shin; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL ENGINEERING
|
| The response of coated, metallic structures subjected to shock pressure waves is studied. The coating is either an elastic material or nearly incompressible rubber of variable stiffness separating the structure from an air or water medium. The stress, nodal velocity, and internal energy of the coated structure are compared to a system without a coating (homogeneous system) to examine the effect of various coating types and configurations on the response ... |
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| Numerical Investigation of Surface Curvature Effects in Compressible Turbulent Flows |
02 DEC 94 |
37 pages |
| Authors:
Linda D. Kral; John F. Donovan; MCDONNELL DOUGLAS AEROSPACE ST LOUIS MO
|
| The objective of this work has been to develop a direct numerical simulation capability for compressible, non-canonical wall-bounded flows which is directly applicable to actual flight vehicles. Data from the simulations is used to educe information about the organized motion. In the flow and bow they are affected by the extra strain rates due to concave wall curvature. A second- order finite volume approach and both fourth-order and sixth-order compact ... |
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| Response of Dual-Layered Structures Subjected to Shock Pressure Wave |
DEC 94 |
85 pages |
| Authors:
Thomas P. Brasek; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The response of coated, metallic structures subjected to shock pressure waves is studied. The coating is either an elastic material or nearly incompressible rubber of variable stiffness separating the structure from an air or water medium. The stress, nodal velocity, and internal energy of the coated structure are compared to a system without a coating (homogeneous system) to examine the effect of various coating types and configurations on the response ... |
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| A Fast Numerical Method for Isothermal Resin Transfer Mold Filling |
NOV 94 |
34 pages |
| Authors:
R. S. Maier; T. F. Rohaly; S. G. Advani; K. D. Fickie; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| An efficient numerical scheme is presented for simulating the isothermal flow in resin transfer molding (RTM). The problem involves transient, free surface flow of an incompressible fluid into a nondeforming porous medium. A new variant of the control volume finite element (CVFE) algorithm is explained in detail. It is shown how the pressure solutions at each time step can be obtained by adding a single row and column to the ... |
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| Mode I Large Strain Viscoelastic Crack Behavior in Nitrile Rubber Sheets |
OCT 94 |
41 pages |
| Authors:
Claudia J. Quigley; Joey L. Mead; ARMY RESEARCH LAB WATERTOWN MA MATERIALS DIRECTORATE
|
| A finite element analysis of a Mode I crack in a viscoelastic, hyperelastic, and incompressible material was performed under relaxation conditions. Loading of the finite element model was applied until the far field strain reached 50%; the viscoelastic material was then allowed to relax for 15 minutes. The numerical results were compared to experimental material behavior. The applied load and stretch ratio histories obtained from the finite element analysis agreed ... |
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| A Fast Numerical Method for Isothermal Resin Transfer Mold Filling |
13 MAY 94 |
22 pages |
| Authors:
R. S. Maier; T. F. Rohaly; S. G. Advani; K. D. Fickie; MINNESOTA UNIV MINNEAPOLIS
|
| An efficient numerical scheme is presented for simulating isothermal flow in resin transfer molding (RTM). The problem involves transient, free- surface flow of an incompressible fluid into a nondeforming porous medium. A new variant of the control volume finite element (CVFE) algorithm is explained in detail. It is shown how the pressure solutions at each time step can be obtained by adding a single row and column to the Cholesky ... |
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| The Effect of Constitutive Law Perturbations on Finite Antiplane Shear Deformations of a Semi-Infinite Strip |
SEP 1993 |
28 pages |
| Authors:
C. O. Horgan; L. E. Payne; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF APPLIED MATHEMATICS
|
| This paper is concerned with assessing the effects of small perturbations in the constitutive laws on antiplane shear deformation fields arising in the theory of nonlinear elasticity. The mathematical problem is governed by a second-order quasilinear partial differential equation in divergence form. Dirichlet (or Neumann) boundary-value problems on a semi- infinite strip, with nonzero data on one end only, are considered. Such problems arise in investigation of Saint-Venant end effects ... |
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| A Bifurcation Approach Modeling Cavitation in Anisotropic Nonlinearly Elastic Solids |
MAY 1993 |
172 pages |
| Authors:
Debra A. Polignone; VIRGINIA UNIV CHARLOTTESVILLE SCHOOL OF ENGINEERING AND APPLIED SCIENCE
|
| In this thesis, material anisotropy and the phenomena of void formation and growth (cavitation) in nonlinearly elastic incompressible solids are considered. We first discuss materials which are transversely isotropic in the contexts of linear and nonlinear hyperelasticity, and derive important constitutive restrictions on the nonlinear stored-energy function, W, by relating W to the associated infinitesimal elastic moduli. We then propose a class of stored-energy functions satisfying these conditions to model ... |
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| Numerical Methods for Explosion Plume Predictions |
12 MAR 93 |
48 pages |
| Authors:
W. G. Szymezak; A. B. Wardlaw; NAVAL SURFACE WARFARE CENTER SILVER SPRING MD
|
| A computational study has been conducted of the plume created by an underwater explosion. Calculations have been performed with a compressible and an incompressible method. The later method was found to be more economical in treating the relatively long-term phenomena associated with the explosion plume, which takes several seconds to form and decay. Both techniques suggest that the formation of an explosion plume can be divided into five different phases: ... |
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| Equibiaxial Testing of TP-14AX Carbon Black Rubber Sheets |
AUG 92 |
37 pages |
| Authors:
Robert P. Bamberg; Ronald R. Aghababian; Christopher Cavallaro; Arthur R. Johnson; ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB
|
| The classical inflation test for thin rubber disks was used to obtain equibiaxial stress-stretch data for a carbon black filled rubber (TP-14AX). Details of the experimental setup, test procedure, measured data, and material constants obtained from the data are reported. A review of how to use the measured test data with tensile stress-stretch data to obtain the material constants is presented. Complete results (data to material constants) for three test ... |
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| Basic Hydrodynamics |
04 DEC 91 |
10 pages |
| Authors:
G. C. Lauchle; PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
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| Basic hydrodynamic studies in turbomachinery and hydrodynamic drag reduction have been conducted. In the turbomachinery thrust area, the overall objective is to develop an improved understanding of the complex three- dimensional flows typical of incompressible rotor and stator flows; this effort has been primarily computational in nature. The second thrust area is axisymmetric turbulent flow drag reduction through microbubble injections. The third thrust area objective is to assess experimentally the ... |
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Reports by Keyword(s)
INCOMPRESSIBILITY
