| Influence of Structural Flexibility on Flapping Wing Propulsion |
Jun-2009 |
180 pages |
| Authors:
Aaron M McClung; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
|
 | The influence of structural deformations on the aerodynamic response of a flapping wing configuration was examined using Navier-Stokes based simulation. Two deformation modes, torsion and bending, were considered for an elastic axis along the leading edge of the wing. Both deformation modes influence the velocity and acceleration profile of the wing surface, altering the unsteady aerodynamic phenomena produced by the dynamic wing motion. The spanwise feathering rotation, or torsional response, ... |
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| Interdisciplinary Research Programs in Geophysical Fluid Dynamics |
Jun-2009 |
6 pages |
| Authors:
John A Whitehead; Neil J Balmforth; Philip J Morrison; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF PHYSICAL OCEANOGRAPHY
|
| The Geophysics Fluid Dynamics (GFD) program consists of a summer study school often weeks duration each summer. The primary aim ol the program is to visit a different specific area of GFD each summer, review fundamentals, and to help each other to conduct original research. Participants are approximately ten graduate student fellows, visiting graduate students and both visiting and returning scientists. The first two weeks consist of principal lectures in ... |
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| Flow Simulations: The Lagrangian Averaged Navier-stokes Equations and Optimization |
19-May-2009 |
11 pages |
| Authors:
Kamran Mohseni; COLORADO UNIV AT BOULDER DEPT OF AEROSPACE ENGINEERING SCIENCES
|
| This project had two objectives in using Lagrangian techniques and their application in flows. The first research thrust area was to develop a modeling technique that will allow for efficient computation of compressible flows which could include simulations involving both shock and turbulent behavior. Spatial averaging of the nonlinear convective term was applied to the Burgers and Euler equations. The second research thrust area was the development of Lagrangian averaging ... |
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| Comprehensive Environmental Measurements from Autonomous Profiling Floats |
12-May-2009 |
3 pages |
| Authors:
Thomas B Sanford; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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| The PI attended three ONR workshops to discuss and help define the future integrated observational program for the Quantifying, Predicting and Exploiting Uncertainty (QPEU), more specifically to help formulate an experiment to study the Kuroshio intrusion, nonlinear internal waves (NLIWs), internal tides, inertial waves, and turbulence mixing resulting from the Kuroshio-topography interaction. The resulting plan is briefly discussed. |
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| High Reynolds Number Turbulence |
07-May-2009 |
10 pages |
| Authors:
Alexander J Smits; PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| The objectives of the grant are to provide a systematic study to fill the gap between existing research on low Reynolds number turbulent flows to the kinds of turbulent flows encountered on full-scale vehicles. We are specifically interested in (1) the behavior of wakes at high Reynolds numbers with increasing complexity, varying from axisymmetric wakes, to wakes typical of submarine shapes that include the effects of a sail, fins, and ... |
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| Non-linear Internal Wave Evolution in the South China Sea: 2005 Field Program |
01-May-2009 |
6 pages |
| Authors:
Robert Pinkel; SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA MARINE PHYSICAL LAB
|
| This program funded by the Office of Naval Research under grant N00014-05-1-0140 is a 2005 field program (SCS05), where our primary challenge was to see if the waves arriving at the western slopes of the South China Sea were in fact, propagating trans-basin from generating sites to the east. |
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| Implicit and P-Multi-Grid Algorithms for High-Order Spectral Difference Method on Unstructured Grids |
May-2009 |
6 pages |
| Authors:
Z J Wang; IOWA STATE UNIV AMES DEPT OF AEROSPACE ENGINEERING
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| The development of high-order methods (order of accuracy 2nd order) on unstructured grids is widely viewed as a major pacing item in computational fluid dynamics (CFD). Efficient high-order methods capable of handling complex geometries are required to compute vortex dominated flows, and to perform large eddy simulation and direct numerical simulation with complex configurations, and to predict aeroacoustic noise generation and propagation. The primary objective of the present research is ... |
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| Considerations for Modeling Flow Control Structures in ADaptive Hydraulics (ADH) |
May-2009 |
8 pages |
| Authors:
Charlie Berger; Gaurav Savant; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| This System-Wide Water Resources Program (SWWRP) technical note presents the incorporation of reversible flow-control structures to the two-dimensional (2-D) Shallow- Water (SW2) module of ADaptive Hydraulics (ADH). The SW2 module can model the obstruction to flow directly; however, the grid detail required for evaluating flow field impacts is cumbersome for the user to readily generate. This technical note details a quick and easy method to describe the structure and model ... |
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| Collaborative Research: Lagrangian Modeling of Dispersion in the Stable Boundary Layer and Canopy Environments |
16-Apr-2009 |
16 pages |
| Authors:
Peter P Sullivan; Jeffrey C Weil; Edward G Patton; COLORADO UNIV AT BOULDER COOPERATIVE INST FOR RESEARCH IN ENVIRONMENTAL SCIENCES
|
| The objective of this research was to improve our understanding of dispersion in the planetary boundary layer (PBL) by extending our Lagrangian particle dispersion model (LPDM) to the stable boundary layer (SBL) and to PBLs interacting with vegetation canopies. The LPDM was driven by large-eddy simulations (LESs). For the SBL, dispersion simulations of a weakly stable PBL demonstrated the slow dispersion rate caused by the stable stratification and showed that ... |
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| Towards High-Reynolds-Number Quiet Flow in Hypersonic Wind Tunnels |
13-Apr-2009 |
32 pages |
| Authors:
Steven P Schneider; PURDUE UNIV LAFAYETTE IN AEROSPACES SCIENCES LAB
|
| This grant was initially focused on developing high-Reynolds-number quiet 0-ow in the Boeing/AFOSR Mach-6 Quiet Tunnel at Purdue. Reliable quiet 0-ow was achieved at freestream unit Reynolds numbers of more than 3 million per foot, beginning in Sept. 2006. The facility became the only operational hypersonic quiet tunnel, anywhere in the world. Tunnel noise was then shown to have a substantial effect on: (a) roughness-induced transition for the X-51A forebody ... |
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| Biologically Inspired Polymer Microfibrillar Arrays for Mask Sealing |
Apr-2009 |
21 pages |
| Authors:
Eugene Cheung; Metin Sitti; Burak Aksak; CARNEGIE-MELLON UNIV PITTSBURGH PA
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| Previous work to develop a microfibrillar array to improve mask sealing performance demonstrated increased wet and dry adhesion on rigid and soft smooth substrates using spatulate fibers. The current effort modeled and characterized dry fibrillar adhesion to substrates that more closely approximate human skin. The models for adhesion to soft, textured substrates revealed that the resulting adhesion was simply a fraction of the adhesion to a smooth, rigid substrate. The ... |
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| Chemical Modeling for Large-Eddy Simulation of Turbulent Combustion |
31-Mar-2009 |
41 pages |
| Authors:
Heinz Pitsch; LELAND STANFORD JUNIOR UNIV CA
|
| In the present project the focus was on developing advanced combustion models for large-eddy simulations (LES) and to develop automatic chemistry reduction techniques and reduced chemical mechanisms for JP-8 surrogate fuels. The aim of the combustion LES modeling part was to advance the models for non-premixed and premixed combustion towards a generalized combustion model that covers all combustion regimes. Towards this end, for the premixed regime, a dynamic model for ... |
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| Interface Conditions for Hybrid RANS/LES Simulations of Complex and Compressible Flows |
06-Mar-2009 |
31 pages |
| Authors:
Ugo Piomelli; Elias Balaras; MARYLAND UNIV COLLEGE PARK DEPT OF MECHANICAL ENGINEERING
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| We have demonstrated the applicability of synthetic turbulence coupled with the controlled-forcing method to generate eddies at the interface between RANS and LES in hybrid calculations. We obtained shorter transition regions and improved model accuracy. Realistic turbulence can be generated within 5 boundary-layer thicknesses of the RANS/LES interface even in cases in which the data supplied by the RANS is inaccurate, or the assumptions on which the forcing is based ... |
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| Periodic Control of Turbulent Boundary Layers |
03-Mar-2009 |
21 pages |
| Authors:
John Kim; Jason L Speyer; AIR FORCE OFFICE OF SCIENTIFIC RESEARCH ARLINGTON VA
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| Over the last two and a half years, control strategies were developed to reduce viscous drag in turbulent boundary layers, in particular, by expanding on the recent discovery that simple two dimensional, streamwise sinusoidal waves traveling upstream sustain a channel flow with sublaminar drag. This simple open-loop control of wall-bounded blowing and suction modifies the Reynolds shear stress distribution to directly reduce drag. This reduction is predicted by linear theory ... |
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| The Distribution of Breaking and Non-Breaking Wave Impact Forces |
Mar-2009 |
40 pages |
| Authors:
Anne M Fullerton; Ann Marie Powers; Don C Walker; Susan Brewton; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD HYDROMECHANICS DIRECTORATE
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| The magnitude of wave impact loads varies greatly, depending upon whether the wave is breaking, as well as on the wave height, length, steepness, and the geometry and immersion of the impacted structure. This report describes an experiment that was performed to characterize the distribution of breaking and non-breaking wave impact loads over a surface, similar to those performed in 2005 with non-breaking wave impact loads and those performed in ... |
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| Using the Advanced Research Version of the Weather Research and Forecast Model in Support of ScanEagle Unmanned Aircraft System Test Flights |
Mar-2009 |
42 pages |
| Authors:
Robert Flanigan; Jeffrey E Passner; Robert E Jr; Dumais; Stephen Kirby; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM COMPUTATIONAL AND INFORMATION SCIENCE DIRECTORATE
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| The U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) supported unmanned aircraft flights in a specified airspace domain at Yuma Proving Ground (YPG) in November and December 2007. The Battlefield Environment Division of the Computational and Information Sciences Directorate (CISD), Army Research Laboratory (ARL), was asked to provide real-time meteorological modeling support and weather products such as low-level wind and turbulence forecasts at YPG to help determine areas and ... |
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| Satellite Reentry Control Via Surface Area Amplification |
Mar-2009 |
128 pages |
| Authors:
Salvador Aleman; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This project endeavors to find whether it is feasible to use an increase in surface area as a way of increasing the drag on an orbiting object, thus decreasing its orbital lifetime. The surface area increase can be achieved by an apparatus that deploys a balloon. The balloon will act as a parachute that will decrease the potential energy of the object through atmospheric drag. This is most effective by ... |
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| Computational Analysis of Geometric Effects on Strut Induced Mixing in a Scramjet Combustor |
Mar-2009 |
74 pages |
| Authors:
Matthew G Bagg; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| In order to increase the fuel-air mixing in a scramjet combustion section, the Air Force Institute of Technology and the Air Force Research lab investigated methods to increase the mixing efficiency. Previous experimental work identified the advantages of using a strut upstream of a cavity flame holder to increase the fuel-air mixture. In this paper a computational investigation of strut injectors in a supersonic flow with a cavity flame holder ... |
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| Static Stability Assessment of an ELCAS(M) Based Barge Crane |
Mar-2009 |
44 pages |
| Authors:
Erick T Huang; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
| This effort performs an engineering assessment to quantify the lift capacity of a temporary barge crane for cargo transfer in calm water at the waterfront. The assessment addresses two basic aspects concerning the effectiveness and operational safety of a barge crane: (a) the barge capacity to accommodate a mobile crane and (b) the crane boom capacity on a floating platform. Prospective barges were assessed for their capacity against capsizing in ... |
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| Least-Squares Finite Element Formulation for Fluid-Structure Interaction |
Mar-2009 |
276 pages |
| Authors:
Cody C Rasmussen; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| Fluid-structure interaction problems prove difficult due to the coupling between fluid and solid behavior. Typically, different theoretical formulations and numerical methods are used to solve fluid and structural problems separately. The least-squares finite element method is capable of accurately solving both fluid and structural problems. This capability allows for a simultaneously coupled fluid structure interaction formulation using a single variational approach to solve complex and nonlinear aeroelasticity problems. The least-squares ... |
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| An Investigation of Shock Wave Physics via Hybrid CFD-BGK Solution Methods for Nonequilibrium Flows |
Mar-2009 |
92 pages |
| Authors:
Brook I Bentley; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| The Unified Flow Solver, a hybrid continuum-rarefied code, is used to investigate the internal structure of a normal shock wave for a Mach range of 1.55 to 9.0 for Argon, and 1.53 to 3.8 for diatomic Nitrogen. Reciprocal shock thickness, density, temperature, heat flux, and the velocity distribution function are calculated for a one-dimensional shock wave and compared with experimental data from Alsmeyer and DSMC results from Bird. Using the ... |
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| Coastal Jets and Their Interactions Along the Central California Coastline |
Mar-2009 |
85 pages |
| Authors:
Liam J Lynam; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis research focuses on the cause of strong southerly winds around the Monterey Peninsula and particularly on the effects of winter storms that produced strong southerly winds. The high-wind events from 2005 through 2008 were analyzed. During this period, 16 cases were identified that met the criteria of high winds around the Monterey Peninsula. From the 16 cases, three cases were chosen to complete a detailed analysis of the ... |
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| Development of Non-Uniform Radiation Solution Methods for Atmospheric Re-entry Using Detailed Thermal Modeling |
Mar-2009 |
68 pages |
| Authors:
Jeffrey R Komives; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The line-by-line accurate spectral radiation solver SPRADIAN was integrated with the multi-temperature hypersonic flow-solver NH7Air for the purpose of predicting the radiation incident on the surface of a hypersonic re-entry vehicle. Atomic and molecular radiation mechanisms are considered for chemical species present in an Earth atmosphere re-entry. A new numerical method of radiation propagation is presented that is capable of accurately predicting the radiation propagation through a non-uniform radiation field. ... |
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| Factors of Safety for Richardson Extrapolation |
Mar-2009 |
65 pages |
| Authors:
Fred Stern; Tao Xing; IOWA UNIV IOWA CITY IIHR - HYDROSCIENCE AND ENGINEERING
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| A factor of safety (FS) method for quantitative estimates of grid/time uncertainties for CFD solutions is derived to remove the deficiencies of GCI, corrected GCI(sub C), and correction factor (CF) methods, i.e., unreasonably small uncertainty when CF 1 (estimated order of accuracy greater than theoretical) and lack of statistical analysis to prove 95% confidence for the estimated uncertainties to bound the true error. The approach follows the CF method but ... |
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| Nonlinear Dynamics and Control of Three-Dimensional Separated Flows |
28-Feb-2009 |
6 pages |
| Authors:
George Haller; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MECHANICAL ENGINEERING
|
| Our objective in this project was to derive a mathematically exact theory of unsteady fluid flow separation. We have obtained analytic formulae for the location and shape of separation profiles in terms of measurable, wall-based physical quantities. These formulae can now be used to design feedback controllers that alter, destroy, or create separation. Our main achievements are as follows: (1) We have developed a mathematical theory of unsteady three-dimensional separation ... |
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| Hybrid LES of Detonations in Reacting Multi-Phase Mixtures |
28-Feb-2009 |
166 pages |
| Authors:
Suresh Menon; Franklin Genin; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| A Large-Eddy Simulation (LES) methodology adapted to the resolution of high Reynolds number turbulent flows in supersonic conditions was proposed and developed. A novel numerical scheme was designed, that switches from a low-dissipation central scheme for turbulence resolution to a flux difference splitting scheme in regions of discontinuities. A state-of-the-art closure model was extended in order to take compressibility effects and the action of shock / turbulence interaction into account. ... |
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| Efficient Simulation and Novel Modeling by Using Generic Three-Dimensional Exact Solutions to Analyze Transport Dynamics in Turbulent Vortices |
28-Feb-2009 |
17 pages |
| Authors:
Sukalyan Bhattacharya; TEXAS TECH UNIV LUBBOCK
|
| In this project, we have formulated an alternative boundary-layer theory. This new analysis will be able to mathematically describe flow-separation unlike the classical theory. In our research, we have partially validated the developed theory and concluded that approach has considerable potential to account for flow-separation. The effective description of separated flow can potentially lead to a fast simulation-algorithm for aerodynamic computation. Our estimate predicts that this semianalytical scheme will compute ... |
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| Towards High-Reynolds Number Quiet Flow in Hypersonic Tunnels |
23-Feb-2009 |
17 pages |
| Authors:
Doyle D Knight; Hadassah Naiman; RUTGERS - THE STATE UNIV NEW BRUNSWICK NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| The report summarizes a research program focused on two main issues related to the achievement of high Reynolds number quiet flow in hypersonic tunnels, namely, 1) automated optimal design of quiet hypersonic tunnels, and 2) tunnel startup in the presence of blunt models. In the former case, a fully automated optimal design methodology was developed to determine the optimal shape of the supersonic nozzle to achieve laminar flow on the ... |
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| Stochastic Analysis and Control of Transonic Helicopter Aerodynamics and Supersonic Projectiles |
02-Feb-2009 |
6 pages |
| Authors:
Sivaguru S Sritharan; WYOMING UNIV LARAMIE
|
| The main goal of this project is to develop a systematic mathematical theory for the robust real time feedback control and stochastic analysis of unsteady transonic aerodynamics of helicopter rotor blades, supersonic ballistic projectiles and propagation of blast waves in the presence of adverse external disturbances. The proposed work builds upon similar scientific advances by the principal investigator in the context of incompressible fluid dynamics, magneto-hydrodynamics and combustion models during ... |
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| Eddy-Mean Flow Interactions in Western Boundary Current Jets |
Feb-2009 |
267 pages |
| Authors:
Stephanie N Waterman; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
|
| This thesis examines eddy-mean flow interactions in western boundary current jets via theoretical studies of eddy-mean flow interactions in idealized configurations and an observational analysis to characterize eddy-mean flow interactions in the Kuroshio Extension. Theoretical studies are made of the mechanism by which eddies drive recirculation gyres through nonlinear rectification, and the role that eddies play in the downstream evolution of a baroclinic jet subject to mixed instabilities. The observational ... |
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| Mathematical Fluid Dynamics of Plasma Flow Control Over High Speed Wings |
Feb-2009 |
42 pages |
| Authors:
David Marshall; Alexander V Fedorov; Victor R Soloviev; V M Krivtsov; V G Soudakov; TELEDYNE SCIENTIFIC AND IMAGING LLC THOUSAND OAKS CA
|
| Develop theoretical models and computational tools for SDBD flow control applications. |
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| Integrated Computational/Experimental Study of Turbulence Modification and Mixing Enhancement in Swirling Jets |
07-Jan-2009 |
30 pages |
| Authors:
J Naughton; D Stanescu; S Heinz; R Semaan; M Stoellinger; C Zemtsop; WYOMING UNIV LARAMIE
|
| Swirling jet flows have been studied experimentally and computationally and the results have been compared with theory. Three-component Laser Doppler Anemometry (LDA) measurements have been carried out for swirling jets of various strengths and swirl distributions. Radial profiles of velocity have been obtained from the jet exit to 50 diameters downstream. The experimental results are consistent with previous results and with similarity theory for weakly swirling turbulent jets. However, the ... |
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| Stochastic Nonlinear Aeroelasticity |
Jan-2009 |
41 pages |
| Authors:
Philip S Beran; Ned J Lindsley; Jose Camberos; Mohammad Kurdi; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| This report documents the culmination of in-house work in the area of uncertainty quantification and probabilistic techniques for aeroelasticity. The work was divided into different project areas, including: accurate analysis of limit-cycle oscillations for simple aeroelastic systems with variability; probabilistic prediction of flutter in systems with distributed variability (random fields); optimization of nonlinear dynamic systems (deterministic with intent to transition to risk-quantified optimization), and incorporation of sensitivities into probabilistic analyses. ... |
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| Transition Delay in Hypervelocity Boundary Layers by Means of CO2/Acoustic Instability Interactions |
08-Dec-2008 |
52 pages |
| Authors:
Graham Candler; Ivett A Leyva; Stuart Laurence; Amy W Beierholm; Hans G Hornung; Ross Wagnild; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| A novel method to delay transition in hypervelocity flows over slender bodies by injecting CO2 into the boundary layer of interest is investigated. The results presented here consist of both experimental and computational data. The experimental data was obtained at Caltech's T5 reflected shock tunnel, while the computational data was obtained at the University of Minnesota. The experimental model was a 5 degree sharp cone, chosen because of its relevance ... |
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| Simulation of Flow Past a Sphere using the Fluent Code |
Dec-2008 |
35 pages |
| Authors:
D A Jones; D B Clarke; DEFENSE SCIENCE AND TECHNOLOGY ORGANIZATION VICTORIA (AUSTRALIA) MARITIME PLATFORMS DIV
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| We use the commercial computational fluid dynamics code Fluent to simulate the flow around a sphere in several different flow regimes; steady-state laminar flow at a Reynolds number (Re) of 100, time-dependent laminar flow at Re = 300, and turbulent flow at Re = 10,000 and Re = 1,000,000. These simulations provide a test of the ability of the code to accurately reproduce typical flow structures observed in generic bluff ... |
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| Integration of Microwave Plasma Ignition Into a Multi-Fuel Engine |
Oct-2008 |
14 pages |
| Authors:
James Smith; WEST VIRGINIA UNIV MORGANTOWN
|
| The purpose of this effort was to demonstrate the successful integration of a Quarter-Wave Coaxial Cavity Resonator Plasma Igniter into a multi-fuel engine. The grantee successfully accomplished the objective by demonstrating successful engine operation with both gasoline and jet fuel. Microwave frequency stimulation of the highly ionized combustion mixture, and generation of reactive oxygen species can potentially result in more complete combustion, preventing in-cylinder build-up of deposits and achieving improved ... |
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| HyPAq: Software for the Transient Analysis of Hypersonic Vehicles in Abaqus |
Oct-2008 |
42 pages |
| Authors:
Nigel S Smith; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AIR VEHICLES DIV
|
| The Defence Science and Technology Organisation (DSTO) has embarked upon a research and development program fro air breathing hypersonic vehicles. Part of this program involves the selection and development of software tools useful in the aerothermo-structural design of these vehicles. HyPAq is a hypersonic package for Abaqus - a set of programs and subroutines to be used in conjunction with that particular finite element analysis code. HyPAq interpolates pressures and ... |
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| A Framework for Uncertainty Quantification in Nonlinear Multi-Body System Dynamics |
22-Sep-2008 |
9 pages |
| Authors:
D Negrut; M Datar; D Gorsich; D Lamb; WISCONSIN UNIV-MADISON DEPT OF MECHANICAL ENGINEERING
|
| This paper outlines a methodology for determining the statistics associated with the time evolution of a nonlinear multi-body dynamic system operated under input uncertainty. The focus is on the dynamics of ground vehicle systems in environments characterized by multiple sources of uncertainty: road topography, friction coefficient at the road/tire interface and aerodynamic force loading. Drawing on parametric maximum likelihood estimation, the methodology outlined is general and can be applied to ... |
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| FY07 NRL DoD High Performance Computing Modernization Program Annual Reports |
05-Sep-2008 |
109 pages |
| Authors:
Portia A Shingler; Beth A Howell; NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR COMPUTATIONAL SCIENCE
|
| These reports summarize the accomplishments of the NRL Principal Investigators who received computer allocations on the DoD High Performance Computing Modernization Program Shared Resource Center in FY07. |
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| RDHWT/MARIAH II Hypersonic Wind Tunnel Research Program |
01-Sep-2008 |
165 pages |
| Authors:
M L Laster; C C Limbaugh; J L Jordan; AEROSPACE TESTING ALLIANCE (ATA) ARNOLD AFB TN
|
| The U.S. Air Force sponsored and the USAF Arnold Engineering Development Center directed the Radiantly Driven Hypersonic Wind Tunnel (RDHWT)/ Magnetohydrodynamic Accelerator Research Into Advanced Hypersonics (MARIAH II) Program. This report primarily covers the research for the period from January 2001 through July 2004. The scope of the research program was to develop enabling technologies for a medium-scale hypersonic wind tunnel (MSHWT) that would provide a Mach 8 to 15 ... |
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| Morphing Aircraft Structures: Research in AFRL/RB |
01-Sep-2008 |
35 pages |
| Authors:
Brian Sanders; Shiv Joshi; Jayanth Kudva; Geoffrey J Frank; Franklin E Eastep; Bryan Cannon; Matthew P Snyder; Jason C Bowman; Gregory W Reich; Terrence Weisshaar; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| This report reviews research in several different areas related to morphing aircraft structures undertaken in AFRL/RBSA. The first is an aeroelastic analysis of a folding-wing vehicle to determine the flutter boundaries of the wing at different fold angles. The second is the development of a simulation tool to study both the flight stability of a morphing vehicle during the morphing process, and the kinematic stability of the morphing mechanism subject ... |
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| Mechanical Response of an Al-PTFE Composite to Uniaxial Compression Over a Range of Strain Rates and Temperatures |
01-Sep-2008 |
28 pages |
| Authors:
Daniel T Casem; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Compressive stress-strain curves were generated for a pressed and sintered mixture of polytetrafluoroethylene and aluminum powders. Experiments were performed at strain rates ranging from 0.001 to 8000/s using a servo-hydraulic load frame and a split Hopkinson pressure bar. High-rate experiments were also performed over a temperature range of 22-78 C. The data is fit to the Johnson-Cook and Modified Johnson-Cook constitutive equations and also to a Zerilli-Armstrong equation adapted for ... |
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| The Key Role of Surface Tension in the Theory of Bubble-Assisted Explosion/Combustion Triggering |
01-Sep-2008 |
20 pages |
| Authors:
Michael Grinfeld; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| We have revised the classical and widely accepted theory of (Bowden, F. P.; Yoffe, A. D. The Initiation and Growth of Explosion in Liquids and Solids; Cambridge University Press: New York, NY, 1952) explaining the initiation of explosion/combustion by means of adiabatic compression of the dissolved gaseous bubbles within condensed liquid substances. The main thrust of our study is to explore the role of surface tension at the interface liquid ... |
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| Simulation of Compressible Multi-Phase Turbulent Reacting Flows |
01-Sep-2008 |
53 pages |
| Authors:
Suresh Menon; Franklin Genin; GEORGIA INST OF TECH ATLANTA SCHOOL OF AEROSPACE ENGINEERING
|
| Simulation of multi-phase, turbulent reacting flow is in itself a very complex task but when such flows occur in the presence of strong, unsteady shocks additional complexity can arise. Shock interactions with shear turbulence can change turbulent structures and shock induced heating can trigger ignition, combustion and turbulent flame propagation. In this research, a new and an efficient large-eddy simulation (LES) strategy has been developed to investigate turbulent flows in ... |
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| Mass Remaining During Evaporation of Sessile Drop |
01-Sep-2008 |
35 pages |
| Authors:
James E Danberg; SCIENCE APPLICATIONS INTERNATIONAL CORP (SAIC) ABINGDON MD
|
| A theory to predict the evaporation rate of HD (mustard agent) for the special case of a glass substrate has been developed. This is an important reference case for the wind tunnel and field test measurements of the HD evaporation rate. The HD drop is treated as a spherical segment with a constant base diameter characterized by the variation of the droplet shape factor (height to base diameter) or contact ... |
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| Wave Climate and Littoral Sediment Transport Study for Virginia Beach, VA - Rudee Inlet to Cape Henry, Hydraulic Model Study |
01-Sep-2008 |
145 pages |
| Authors:
Michael J Briggs; Edward F Thompson; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
|
| The Norfolk District is preparing an Environmental Assessment for the use of sand sources off the coast of Cape Henry for future maintenance of the Virginia Beach, VA, shoreline. The primary purpose is to maintain a buffer for hurricane protection for structures landward of the existing beach. The Cape Henry Borrow Area is being considered as a sand source. The plan borrow scenario involves removing approximately 34.2 M cu yd ... |
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| A High-Order, Adaptive, Discontinuous Galerkin Finite Element Method for the Reynolds-Averaged Navier-Stokes Equations |
01-Sep-2008 |
184 pages |
| Authors:
Todd A Oliver; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF AERONAUTICS AND ASTRONAUTICS
|
| This thesis presents high-order, discontinuous Galerkin (DG) discretizations of the Reynolds-Averaged Navier-Stokes (RANS) equations and an output-based error estimation and mesh adaptation algorithm for these discretizations. In particular, DG discretizations of the RANS equations with the Spalart-Allmaras (SA) turbulence model are examined. The dual consistency of multiple DG discretizations of the RANS-SA system is analyzed. The approach of simply weighting gradient dependent source terms by a test function and integrating ... |
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| Navier-Stokes Predictions of Dynamic Stability Derivatives: Evaluation of Steady-State Methods |
Sep-2008 |
44 pages |
| Authors:
Paul Weinacht; James DeSpirito; Sidra I Silton; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The prediction of the dynamic stability derivatives-roll-damping, Magnus, and pitch-damping moments-were evaluated for three spin-stabilized projectiles using steady-state computational fluid dynamic (CFD) calculations. Roll-damping CFD predictions were found to be very good across the Mach number range investigated. Magnus moment predictions were very good in the supersonic flight regime; however, the accuracy varied in the subsonic and transonic flight regime. The best Magnus moment prediction in the subsonic flight regime ... |
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| Factors of Safety for Richardson Extrapolation for Industrial Applications |
Sep-2008 |
18 pages |
| Authors:
Fred Stern; Tao Xing; IOWA UNIV IOWA CITY IIHR - HYDROSCIENCE AND ENGINEERING
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| Improved factors of safety for quantitative estimates for grid and time convergence uncertainties for CFD solutions are proposed for situations when Richardson extrapolation estimated order of accuracy P(sub k) is larger than the theoretical order of accuracy P(sub k(th)) and correction factor 1C(sub k)2. The improved uncertainty estimates are shown to provide more reasonable intervals of uncertainty for P(sub k) P(sub k(th)) (1C(sub k)2). |
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| Dynamic Multiscale Simulation of Polyelectrolyte Nanoassemblies |
21-Aug-2008 |
11 pages |
| Authors:
Satish Kumar; MINNESOTA UNIV MINNEAPOLIS
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| The goal of this project is to develop a fundamental understanding of how fluid flows, electric fields, and surface patterning affect polyelectrolyte adsorption, self-assembly, and transport near solid surfaces. Polyelectrolytes are charged polymers whose behavior is central to Army-relevant technologies (e.g., biochemical sensors, surface functionalization) but poorly understood. Brownian dynamics simulations---a coarse-grained simulation method suitable for describing non-equilibrium polymer behavior---have been applied to study polyelectrolyte adsorption in shear flow, polyelectrolyte ... |
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Fluid Mechanics
