| Measuring the Spatial Distribution of Ripples Using REMUS AUV |
10 OCT 2007 |
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| Authors:
Wayne R. Geyer; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF APPLIED OCEAN PHYSICS AND ENGINEERING
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 | The long term goal of this work is to increase our understanding of bedform geometry and processes associated with bedforms on the continental shelf. To do this we have been developing novel measurement techniques, conducting observations of both the spatial and temporal variability of ripples and developing a variety of model approaches. |
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| Anchoring-Induced Texture & Shear Banding of Nematic Polymers in Shear Cells |
01-Oct-2007 |
28 pages |
| Authors:
Qi Wang; Hong Zhou; M G Forest; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MATHEMATICS
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 | We numerically explore texture (resolved by the second-moment of the orientational distribution) and shear banding of nematic polymers in shear cells, allowing for one-dimensional morphology in the gap between parallel plates. We solve the coupled Navier-Stokes and Doi-Marrucci-Greco orientation tensor model, considering both confined orientation in the plane of shear and full orientation tensor degrees of freedom, and both primary flow and vorticity (in the full tensor model) components. This ... |
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| A CFD Study of the Aerodynamics of a 6x6x8 Foot Cargo Container Suspended Beneath a Helicopter. Part 1: Aerodynamics of the Stationary Container |
OCT 2007 |
78 pages |
| Authors:
Johannes N. Theron; Earl P. Duque; Luigi Cicolani; NORTHERN ARIZONA UNIV FLAGSTAFF
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| This report is the first of several on a study of the unsteady aerodynamics of the CONEX cargo container This work is in support of an effort to develop a model of the CONEX unsteady aerodynamics for use in simulations of helicopter-slung-load dynamics It is known from the literature on cargo container aerodynamics that instability is caused by unsteady flow effects such as vortex shedding and flow structure lags and ... |
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| Vortex-Induced Vibration: Universal Phenomena in Diverse Systems |
OCT 2007 |
14 pages |
| Authors:
Charles H. Williamson; CORNELL UNIV ITHACA NY OFFICE OF SPONSORED PROGRAMS
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| The long-term goals of the research under this award have been to discover and understand generic phenomena in a whole class of vortex-induced vibration systems. We discover, using novel controlled damping, that the immense scatter in the classical Griffin plot (peak amplitude versus mass-damping) over 3 decades, can now be collapsed beautifully if one renormalises the axes, taking into account the effect of Reynolds number, which was previously not considered. ... |
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| An Experimental Investigation Into The Effect Of Plasma On The Flow Features Of An Axisymmetric Jet |
OCT 2007 |
387 pages |
| Authors:
Richard E. Huffman; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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| The main goal of the research presented was to determine the differences between a plasma field and neutral field flow structure (both mean and turbulent effects) for varying Mach number. The overall objective was to describe the effect of radio frequency capacitively coupled plasma on the flow features of compressible axisymmetric jets in Nitrogen. Three flows were investigated: perfectly expanded jets, highly underexpanded jets, and jets created by a constant-diameter ... |
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| Development of a Simple Soil Moisture Model in the Hydrologic Simulator GSSHA |
OCT 2007 |
9 pages |
| Authors:
Charles W. Downer; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| The purpose of this System-Wide Water Resources Program (SWWRP) technical note is to describe the development and application of simplified unsaturated zone modeling in the Gridded Surface Subsurface Hydrologic Analysis model (GSSHA) (Downer et al. 2005). This new method was developed to increase the applicability of the GSSHA model to high resolution coupled surface-water/groundwater simulations of large basins that may be limited by excessive simulation times or accuracy of methods ... |
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| A Primer for the Linkage Between Unstructured Water Quality Model CE-QUAL-ICM and Structured Three-Dimensional Hydrodynamic Model CH3D-WES |
OCT 2007 |
59 pages |
| Authors:
Sung-Chan Kim; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| This Water Quality Research Program (WQRP) Technical Note (TN) describes the linkages between water quality model CE-QUAL-ICM (ICM) and three-dimensional hydrodynamic model CH3D-WES: CH3D. This TN also presents a primer for the linkages through a set of MATLAB programs. The created linkage files enable seamless operation from CH3D to ICM. |
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| Numerical and Experimental Investigation of Microchannel Flows with Rough Surfaces (Postprint) |
OCT 2007 |
10 pages |
| Authors:
T. C. Lilly; J. A. Duncan; S. L. Nothnagel; S. F. Gimelshein; N. E. Gimelshein; A. D. Ketsdever; I. J. Wysong; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| A conical surface roughness model applicable to particle simulations has been developed. The model has been experimentally validated for channel flows using helium and nitrogen gases at Reynolds numbers from 0.01 to 10 based on inlet conditions. To efficiently simulate gas-surface interaction, molecular collisions with the actual rough surface are simulated by collisions with a randomly positioned conical hole having a fixed opening angle. This model requires only one surface ... |
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| Characterization of Iodine Quenching and Energy Transfer Rate Constants for Supersonic Flow Visualization Applications |
28 SEP 2007 |
28 pages |
| Authors:
Michael C. Heaven; EMORY UNIV ATLANTA GA DEPT OF CHEMISTRY
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| Planar laser induced fluorescence (PLIF) imaging is being used to study the fluid dynamics of supersonic gas mixing in the nozzle from a chemical oxygen iodine laser (COIL). PLIF images are recorded using laser excitation of the I(sub2) B-X transition. Data for the temperature dependences of the I(sub2)(B) quenching rate constants are needed for the quantitative interpretation of the PLIF data. A Mach 2.6 supersonic nozzle system has been used ... |
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| Operating Characteristics of Cylindrical and Annular Helicon Sources (Preprint) |
22 SEP 2007 |
18 pages |
| Authors:
Brian E. Beal; Fabian Mak; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACECRAFT PROPULSION BRANCH
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| The power required to create an ionized plasma is a significant energy loss mechanism in typical electric propulsion systems. The use of wave-driven helicon sources is one approach that has been considered as a means of reducing this loss due to the reportedly low ionization cost found in these devices. In order to extend the benefits of the helicon ionization mechanism to the widest possible array of devices, a program ... |
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| Towed Array Hydrodynamic Research in the Naval Research Enterprise Intern Program (NREIP) |
20 SEP 2007 |
24 pages |
| Authors:
William L. Keith; Kimberly M. Cipolla; Jane Leous; Elizabeth Scales; NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
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| This memo reproduces a presentation describing the towed array hydrodynamic tests performed by the Naval Undersea Warfare Center (NUWC) Division, Newport, RI, under the Naval Research Enterprise Intern Program. The tests, conducted in June 2007 at the Naval Surface Warfare Center's David Taylor Model Basin in Carderock, MD, were designed to measure the turbulent boundary layer velocity profiles, mean wall shear stress, and wall pressure fluctuations on an experimental towed ... |
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| Multi-Objective and Multidisciplinary Design Optimisation (MDO) of UAV Systems using Hierarchical Asynchronous Parallel Evolutionary Algorithms |
17 SEP 2007 |
100 pages |
| Authors:
L. Damp; L. F. Gonzalez; K. Srinivas; SYDNEY UNIV (AUSTRALIA) SCHOOL OF AEROSPACE MECHANICAL AND MECHATRONIC ENGINEERING
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| Project report from basic science initiative to use Hierarchical Asynchronous Parallel Evolutionary Algorithms for MDO of a UAV system using high fidelity analysis tools. Two production UAV wings were examined for aerodynamic and structural properties. Optimization was performed over 48 design variables. |
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| Modeling of Hurricane Impacts |
01 SEP 2007 |
28 pages |
| Authors:
Dano Roelvink; Ad Reniers; Ap van Dongeren; Jaap van Thiel de Vries; UNESCO-THE INST FOR WATER EDUCATION DELFT (NETHERLANDS)
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| This fourth interim report describes ongoing development and validation of the XBeach model as part of the MORPHOS project and other activities over the period March-August 2007 (period extended due to late approval to continue) |
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| Tomographic Reconstruction of Atmospheric Turbulence with the Use of Time-Dependent Stochastic Inversion |
01-Sep-2007 |
11 pages |
| Authors:
Sergey N Vecherin; Vladimir E Ostashev; A Ziemann; D K Wilson; K Arnold; M Barth; NEW MEXICO STATE UNIV LAS CRUCES DEPT OF PHYSICS
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| Acoustic travel-time tomography allows one to reconstruct temperature and wind velocity fields in the atmosphere. In a recently published paper [S. Vecherin et al., J. Acoust. Soc. Am. 119, 2579 (2006)], a time-dependent stochastic inversion TDSI was developed for the reconstruction of these fields from travel times of sound propagation between sources and receivers in a tomography array. TDSI accounts for the correlation of temperature and wind velocity fluctuations both ... |
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| Turbulence Instrumentation for Stratospheric Airships |
01-Sep-2007 |
83 pages |
| Authors:
Mark L Duell; Lawrence M Saupe; Brent E Barbeau; Kris D Robinson; George Y Jumper; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| Both commercial and high altitude aircraft such as the U-2 may encounter turbulence in flight. The turbulence seems to be associated with buoyancy waves generated by flow over mountains that can break into turbulence. The exact nature of the wave breaking is not fully understood, and forecast models need to be examined to determine their ability to forecast turbulence. The High Altitude Airship is designed to investigate these phenomena. In ... |
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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
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| 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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| Physical and Chemical Processes in Flames |
SEP 2007 |
19 pages |
| Authors:
Chung K. Law; PRINCETON UNIV NJ DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| The objective of the present program was to study the structure and response of laminar premixed and nonpremixed flames with emphases on effects of high pressure, flame/flow unsteadiness, and chemistry. Studies on flame dynamics show strong coupling between the intrinsic flamefront hydrodynamic cellular instabilities and the diffusional/thermal cellular or pulsating instabilities, for mixture Lewis numbers that are respectively smaller or larger than unity. Linear and nonlinear stability analyses on diffusion ... |
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| A Compendium of Resistance, Sinkage and Trim, and Longitudinal Wave Cut Measurements Obtained on Model 5365 |
SEP 2007 |
41 pages |
| Authors:
Toby Ratchliffe; Anne Fullerton; James Rice; Don Walker; Lauren Russell; Thomas Fu; DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD DEPT OF HYDROMECHANICS
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| Model 5365 is a 1/8.25th scale representation of the R/V Athena. This report documents both a new set of resistance, sinkage and trim, and longitudinal wave cut experiments as well as historical calm water resistance and sinkage and trim data which have been obtained on this model over the past few decades. The new resistance data were obtained in October and November of 2006 on Carriage 2 at the Naval ... |
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| Using Computational Fluid Dynamics-Rigid Body Dynamic (CFD-RBD) Results to Generate Aerodynamic Models for Projectile Flight Simulation |
SEP 2007 |
34 pages |
| Authors:
Mark Costello; Stephen Gatto; Jubaraj Sahu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| A method to efficiently generate a complete aerodynamic description for projectile flight dynamic modeling is described. At the core of the method is an unsteady, time-accurate computational fluid dynamics simulation that is tightly coupled to a rigid projectile flight dynamic simulation. A set of short time snippets of simulated projectile motion at different Mach numbers is computed and employed as baseline data. For each time snippet, aerodynamic forces and moments ... |
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| New Outlook on the High-Pressure Behavior of Pentaerythritol Tetranitrate |
SEP 2007 |
26 pages |
| Authors:
Jennifer A. Ciezak; Timothy A. Jenkins; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| To gain insight into the high-pressure behavior of pentaerythritol tetranitrate (C(CH2ONO2)4), single crystal Raman spectroscopy results were obtained for hydrostatic/quasi-hydrostatic and non-hydrostatic compression in a diamond anvil cell. Detailed analyses of the pressure-induced changes in the single-crystal/neon hydrostatic media revealed the splitting of several vibrational modes and many intensity fluctuations, which provide strong evidence for a pressure-induced symmetry modification from S4 to D2 rather than a high-pressure phase transition. Near ... |
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| Electrothermal-Chemical Plasma Ignition of Gun-Propelling Charges: The Effect of Pulse Length |
SEP 2007 |
24 pages |
| Authors:
Lang-Mann Chang; Stephen L. Howard; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| An experimental investigation was conducted on the effect of plasma pulse length on gun-charge ignition. The investigation began with visualization of open-air, capillary-generated plasma jet flows and concluded with plasma interaction with a JA2 propelling charge in a 25-mm gun chamber. The plasma energy utilized by the capillary was about 1.1 kJ. With plasma pulse lengths of 0.3 and 1 ms, the resultant flow fields observed were profoundly different in ... |
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| Evaluation of 5-cm Agent Fate Wind Tunnel Velocity Profiles |
SEP 2007 |
44 pages |
| Authors:
James E. Danberg; SCIENCE APPLICATIONS INTERNATIONAL CORP SAN DIEGO CA
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| Velocity profiles measured in 5-cm Agent Fate wind tunnels have been evaluated for conformance to specified profiles. These facilities are used to determine evaporation and desorption rates of chemical warfare agents (CWA) from various surface materials. The specified profiles represent an atmospheric boundary layer for velocity conditions of 6, 3, and 0.5 m/s at a height of 2 m. The 5-cm tunnels are designed to duplicate the part of this ... |
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| Thrust Breakdown Characteristics of Conventional Propellers |
SEP 2007 |
51 pages |
| Authors:
Scott D. Black; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD PROPULSION AND FLUID SYSTEMS DIV
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| Historically, the Burrill diagram has been used early in the propeller design process to estimate the inception of thrust loss due to cavitation. That data was based on a systematic series of propeller tested in a uniform inflow. This report develops an alternative set of curves based on five modern propeller designs to estimate thrust breakdown for both uniform inflow and for a range of non-uniformities. |
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| Axial Waterjet (AxWJ) Model 5662: Hull Resistance and Model-Scale Powering with LDV Nozzle Design |
SEP 2007 |
72 pages |
| Authors:
Dominic S. Cusanelli; Scott A. Carpenter; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
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| This report is a partial documentation of the first series of model-scale tests conducted 12/06-2/07, to evaluate the Axial Waterjet (AxWJ), Model 5662, on the Joint High Speed Sealift (JHSS) hull platform. This document contains calm water resistance and model-scale powering test results only. Bare hull effective powers were determined for the AxWJ hull at three displacement conditions. Appended effective power was determined for the AxWJ hull with the LDV ... |
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| Computational Fluid Dynamics Results for a 25-mm Projectile |
SEP 2007 |
24 pages |
| Authors:
Karen Heavey; Jubaraj Sahu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Computational fluid dynamics approaches were used to compute the flow fields of a 25-mm projectile, modeled with and without a jet cavity. Steady-state numerical results have been obtained for a series of cases at Mach number 0.756, at 0 deg angle of attack, with jet pressures of 3, 6, and 12 atm. Full three-dimensional computations were performed using a two-equation realizable k-epsilon turbulence model. Force and moment data have been ... |
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| Comparative Study of Aerodynamic Interference During AFT Dispense of Munitions |
SEP 2007 |
173 pages |
| Authors:
Matthew G. Burkinshaw; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| Based on forthcoming USAF needs, an investigation was launched to further the understanding of aft dispense of munitions in a high-speed environment. A computational fluid dynamics (CFD) study was performed followed by a wind tunnel experiment. The study consisted of a strut-mounted cone simulating a parent vehicle and a sting mounted cone-cylinder store situated directly behind the cone. The CFD modeled the test objects inside a supersonic wind tunnel in ... |
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| Structure and Dynamics of the Thermohaline Staircases in the Beaufort Gyre |
SEP 2007 |
77 pages |
| Authors:
Ana L. Wilson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| This study explores the dynamics of diffusive convection which occurs when cold, fresh water overlies warm and salty. The primary convective regime in the Arctic region is characterized by the spontaneous formation of well mixed layers separated by thin high-gradient interfaces known as thermohaline staircases. Data analysis and analytical considerations are used to estimate the vertical heat/salt mixing rates and their dependencies on the large-scale environmental parameters. Based on the ... |
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| Controllability of Non-Newtonian Fluids Under Homogeneous Flows |
SEP 2007 |
65 pages |
| Authors:
Lynda M. Wilson; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| The ability to control a viscoelastic field is an essential concept that defines some important restrictions and potentials of the influenced material. This thesis investigates the controllability of three popular constitutive models under homogeneous extensional and shear flows via the Lie bracket method. The constitutive models are as follows: the Phan-Thien-Tanner model; the Johnson-Segalman model; and the Doi model. The effect of extensional flow on these models and the effect ... |
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| Lagrangian Observations of Rip Currents |
SEP 2007 |
59 pages |
| Authors:
Jonathan D. Morrison; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| A comprehensive field rip-current experiment (RCEX) was conducted from 14 April to 18 May 2007 in Sand City, California, on Monterey Bay. Lagrangian observations were made with inexpensive ($150), handheld, Differential Global Positioning Systems (DGPS) mounted on surf zone drifters. The inexpensive DGPS requires post-processing to achieve O(0.4m) position accuracy and O(0.01m/s) velocity accuracy. Thirty drifters were constructed and deployed in well-developed, rip-currents to map the circulation patterns for the ... |
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| White Sands Missile Range 2007 Urban Study: Flow and Stability Around a Single Building Volume 1: Field Study Overview |
SEP 2007 |
46 pages |
| Authors:
Gail Vaucher; Manuel Bustillos; Robert Brice; Sean D'Arcy; Ron Cionco; Felicia Chamberlain; Joseph Trammel; Saba Luces; Richard Padilla; Jimmy Yarbrough; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
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| In this Field Study Overview, we (1) describe the foundational scientific and engineering aspects of the airflow and stability field study and (2) provide an administrative report on the field study execution with its associated research application drills The six mission objectives driving this project were derived from three general areas: urban atmosphere research, technology advancements and research applications The preliminary results section summarizes the objective successes. The technical report ... |
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| Internal Tide Generation by Steep Topography |
SEP 2007 |
5 pages |
| Authors:
Eric Kunze; Thomas Sanford; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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| The purpose of this proposal was to support Dr. Eric Kunze, Applied Physics Laboratory, University of Washington (now at University of Victoria) and Dr. Pascale Lelong (via a subcontract to Northwest Research Associates, Seattle, Washington) to numerically explore an alternative solution method to Baines' (1982) internal tide generation theory for arbitrary 1-D topography h(x). The solution method uses characteristic coordinates along which signals of frequency omega propagate. |
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| Efficient High-Order Accurate Methods using Unstructured Grids for Hydrodynamics and Acoustics |
31 AUG 2007 |
49 pages |
| Authors:
Dimitri J. Mavriplis; Dan Stanescu; WYOMING UNIV LARAMIE
|
| The objective of this project has been the development of high-order accurate simulation techniques for fluid flow problems of interest to the US Navy, such as hydrodynamics and acoustics. Efficient solution techniques for high-order Discontinuous Galerkin methods have been investigated from both a theoretical and practical standpoint. An h-p multigrid solution strategy which delivers optimal convergence rates which are independent of both the order of accuracy p of the discretization, ... |
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| Experimental Analysis of the Vorticity and Turbulent Flow Dynamics of a Pitching Airfoil at Realistic Flight Conditions |
31 AUG 2007 |
153 pages |
| Authors:
Rodney D. Bowersox; Dipankar Sahoo; TEXAS A AND M UNIV COLLEGE STATION
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| The primary objective of this research proposal was improved understanding of the fundamental vorticity and turbulent flow physics for a dynamically stalling airfoil at realistic helicopter flight conditions. To meet this objective, an experimental program using high-resolution particle image velocimetry was performed. High-resolution planar contours of the instantaneous and mean velocity field on a dynamically pitching NACA 0012 airfoil operating in the Texas A&M University large-scale wind tunnel are planned. ... |
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| Computational Methods for Feedback Controllers for Aerodynamics Flow Applications |
15 AUG 2007 |
92 pages |
| Authors:
Stefan G. Siegel; Juergen J. Seidel; Thomas E. McLaughlin; Kelly Cohen; Selin Aradag; James R. Forsythe; William Z. Strang; COBALT SOLUTIONS LLC SPRINGFIELD OH
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| This report covers the final results of the STTR: "Computational Methods for Feedback Controllers for Aerodynamics Flow Applications." It is intended to be a comprehensive summary of the project. The goal of the project was to provide a robust, easy to use computational tool for developing feedback controllers for aerodynamic flow applications - i.e. a tool to develop closed loop flow control methods. The two major partners of the STTR ... |
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| Turbulent Mixing and Combustion for High-Speed Air-Breathing Propulsion Application |
12 AUG 2007 |
126 pages |
| Authors:
Paul E. Dimotakis; CALIFORNIA INST OF TECH PASADENA DEPT OF AERONAUTICS
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| Work was completed on mixing, chemical-reaction, and combustion processes in turbulent, subsonic, and supersonic flows. Research included high-speed internal flows of interest to scramjet mixing and combustion, aimed at flow-control and flame holding issues. The control authority and mixing in subsonic and transonic flows affected by mass injection and heat release was quantified. In parallel, Large Eddy Simulation (LES) with Sub-Grid Scale (SGS) modeling of these flows was conducted with ... |
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| Experiments in Sound and Structural Vibrations Using an Air-Analog Model Ducted Propulsion System |
AUG 2007 |
104 pages |
| Authors:
Scott C. Morris; NOTRE DAME UNIV IN DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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| The prediction of the radiated acoustic signature of underwater structures has been and will continue to be of great importance for the Navy. New and innovative designs of maneuvering and propulsion systems present challenging problems for the prediction of radiated acoustics. The present research focused on the development of structural acoustic experiments that use air as the working fluid. The test specimens were designed using very light weight structures such ... |
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| Unsteady Flow Computations of a Finned Body in Supersonic Flight |
AUG 2007 |
29 pages |
| Authors:
Jubaraj Sahu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report describes a multidisciplinary computational study undertaken to compute the flight trajectories and simultaneously predict the unsteady free flight aerodynamics of a finned projectile at supersonic speeds with the use of an advanced unstructured time-accurate Navier-Stokes computational technique. Actual flight trajectories are computed with an advanced coupled computational fluid dynamics (CFD)-rigid body dynamics (RBD) technique. In addition, our goal is to be able to extract the aerodynamic coefficients from ... |
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| Unsteady Low-Reynolds Number Aerodynamics for Micro Air Vehicles (MAVs) |
AUG 2007 |
9 pages |
| Authors:
Michael V. Ol; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| This report documents recent progress in in-house research in the AFRL Air Vehicles Directorate on unsteady aerodynamics at low Reynolds number. The application is the aerodynamics and flight dynamics of agile Micro Air Vehicles, to include flapping-wings. Experiments included quantitative and qualitative flowfield velocimetry on the Selig SD7003 airfoil, undergoing a range of harmonic and ramp motions in two degrees of freedom - that is, pitch and plunge. Relevant classical ... |
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| Laboratory Characterization of Solid Grade SW Brick |
AUG 2007 |
88 pages |
| Authors:
Erin M. Williams; Stephen A. Akers; Paul A. Reed; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| Personnel of the Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center, conducted a laboratory investigation to characterize the strength and constitutive property behavior of solid Grade SW brick. A total of 37 mechanical property tests were successfully completed, consisting of two hydrostatic compression tests, four unconfined compression (UC) tests, 12 triaxial compression tests (TXC), two constant mean normal stress tests, four direct pull (DP) tests, two uniaxial ... |
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| Laboratory Characterization of Gray Masonry Concrete |
AUG 2007 |
99 pages |
| Authors:
Erin M. Williams; Stephen A. Akers; Paul A. Reed; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| Personnel of the Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center, conducted a laboratory investigation to characterize the strength and constitutive property behavior of a gray masonry concrete. A total of 38 mechanical property tests were successfully completed: two hydrostatic compression tests, four unconfined compression (UC) tests, 16 triaxial compression (TXC) tests, two uniaxial strain tests, two uniaxial strain load/biaxial strain unload tests, five uniaxial strain load/constant ... |
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| The Effect of Steady Fluid Motion on One-Dimensional Wave Propagation (Postprint) |
AUG 2007 |
13 pages |
| Authors:
Barry Kiel; Reza Kashani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Reduced order modeling of thermoacoustic instabilities involves the coupled modeling of the wave propagation in the combustion chamber and the unsteady heat release. In many combustion systems the Mach number is low enough that the effect of the fluid motion on the wave propagation can be ignored. Ignoring the fluid motion results in the use of the wave equation to model the wave motion in the combustion chamber. In a ... |
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| Non-Reacting and Combusting Flow Investigation of Bluff Bodies in Cross Flow (Postprint) |
AUG 2007 |
13 pages |
| Authors:
Barry Kiel; Kyle Garwick; Amy Lynch; James R. Gord; Terrence Meyer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| This paper is the first in a series of papers studying the behavior of bluff body stabilized flames. In this research a combination of Laser Doppler Velocimetry (LDV), and High Speed Imaging are used to investigate these flames. LDV data taken over several non-combusting operating conditions detail the recirculation zone behind the bluff body as well as the effect of inlet conditions on the Karman Street vortex shedding that occurs. ... |
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| Improved Correlations for Augmentor Static Stability (Postprint) |
AUG 2007 |
12 pages |
| Authors:
Barry V. Kiel; Darin A. Knaus; Patrick J. Magari; Roger W. Hill; Scott D. Phillips; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
|
| Flame stability is critical to the operational performance of combustion systems in propulsion and power generation. Current predictive tools for flame stability are based on decades-old empirical correlations that have limited applicability for modern combustor designs. Recent advances in computational fluid dynamics (CFD) and advanced combustion diagnostics have provided new insight into the fundamental processes that occur in these flows. Reacting-flow CFD has yet to mature to a level where ... |
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| High Performance Damping with Carbon Nanotube-Polymer Composites |
20 JUL 2007 |
28 pages |
| Authors:
Kon-Well Wang; Charles Bakis; PENNSYLVANIA STATE UNIV UNIVERSITY PARK OFFICE OF SPONSORED PROGRAMS
|
| The overall goal of this research project is to investigate the characteristics of carbon nanotube (CNT) filler-based polymers and provide guidelines to advance the state of the art of structural damping enhancement utilizing CNT fillers. Our major efforts have been focused on: (1) To perform tests to observe the damping effect of composites with CNT fillers; (2) To develop a micromechanical constitutive model to analyze the effects of the stick-slip ... |
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| Inverse Analysis of Cavitation Impact Phenomena on Structures |
02 JUL 2007 |
32 pages |
| Authors:
S. G. Lambrakos; N. E. Tran; NAVAL RESEARCH LAB WASHINGTON DC
|
| A general methodology is presented for in situ detection of cavitation impact phenomena on structures based on inverse analysis of luminescent emissions resulting from the collapsing of bubbles onto surfaces. Following an inverse-analysis approach, luminescent emission signatures are correlated with the general structure of asymmetric bubble collapse onto a surface. This method suggests applications for detection of cavitation that can occur within different types of dynamic water environments of structures. ... |
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| Development of Algorithms for Nonlinear Physics on Type-II Quantum Computers |
JUL 2007 |
12 pages |
| Authors:
George Vahala; COLLEGE OF WILLIAM AND MARY WILLIAMSBURG VA
|
| Using CAP resources we have been able to uncover lattice geometry effects in the entropic lattice Boltzmann algorithm that had not been expected from lower grid resolution runs. In the entropic formulation, one is working with a generalized BGK collision operator that has within it the germs of detailed balance. Thus, the unconditionally stable algorithm is achieved with a variable transport coefficient, not unlike Large Eddy Simulations (LES) in CFD. ... |
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| Laboratory Study of Wind Effect on Runup over Fringing Reefs. Report 1. Data Report |
JUL 2007 |
83 pages |
| Authors:
Zeki Demirbilek; Okey G. Nwogu; Donald L. Ward; ENGINEER RESEARCH AND DEVELOPMENT CENTER CHAMPAIGN IL CONSTRUCTION ENGINEERING RESEARCH LAB
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| The report describes experimental data obtained from a wind-wave flume study conducted August-September 2006 at the University of Michigan in Ann Arbor, MI. The study objectives were two-fold: to quantify wind effects on wave runup on fringing reefs of the Pacific Island of Guam and to obtain detailed wave data along a complex reef system consisting of steep slopes and shallow areas for validating wave breaking, dissipation, wave setup and ... |
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| Performance Characterization of the Free Molecule Micro-Resistojet Utilizing Water Propellant (Postprint) |
JUL 2007 |
12 pages |
| Authors:
R. H. Lee; A. M. Bauer; M. D. Killingsworth; T. C. Lilly; J. A. Duncan; Andrew D. Ketsdever; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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| Advances in micro-technology manufacturing and capability have led to an increased interest in micro and nanosatellites. A propulsion system has been designed to meet the on-orbit attitude control requirements for nanospacecraft. The Free Molecule Micro-Resistojet (FMMR), a low cost, low power, high propellant storage density, and green propulsion system, has been analyzed in this study to determine its ability to provide a slew maneuver for a typical 10 kg nanosatellite. ... |
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| Sea Clutter Generation and Target Detection |
JUL 2007 |
26 pages |
| Authors:
Stefano M. Canta; Danilo Erricolo; ILLINOIS UNIV AT CHICAGO CIRCLE COLL OF ENGINEERING
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| Propagation model for the electromagnetic field that accounts for the clutter and metallic objects in the sea. Computationally fast, and the complete work will include electromagnetic propagation models and vector antennas. |
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| Effect of Stress and Strain Path on Cavity Closure During Hot Working of an Alpha/Beta Titanium Alloy (Preprint) |
Jul-2007 |
31 pages |
| Authors:
S L Semiatin; P D Nicolaou; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| The effect of strain path and stress state on deformation and cavitation during hot working of Ti-6Al-4V was established via torsion-compression and reversed-torsion tests. Measurements of the cavity area fraction and the size of individual cavities revealed that the rate of cavity closure during the change in strain path following torsion is approximately twice as large in compression compared to reversed torsion. The observations were interpreted in the context of ... |
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Fluid Mechanics
