A5061783615- Combustion and flame dynamics
- Computational Fluid Dynamics and Aerodynamics
- Fluid Dynamics and Turbulent Flows
- Advanced Combustion Engine Technologies
- Fire dynamics and safety research
- Gas Dynamics and Kinetic Theory
- Wind and Air Flow Studies
- Combustion and Detonation Processes
- Particle Dynamics in Fluid Flows
- Sports Performance and Training
- Probabilistic and Robust Engineering Design
- Muscle activation and electromyography studies
- Aerodynamics and Acoustics in Jet Flows
- High-Velocity Impact and Material Behavior
- Energetic Materials and Combustion
- Lattice Boltzmann Simulation Studies
- Laser-Plasma Interactions and Diagnostics
- Experimental Learning in Engineering
- Cardiovascular and exercise physiology
- Seismic Imaging and Inversion Techniques
- Rocket and propulsion systems research
- Teaching and Learning Programming
- Advanced Adaptive Filtering Techniques
- Image and Signal Denoising Methods
- Balance, Gait, and Falls Prevention
Edwards Air Force Base
2024
Innovative Scientific Solutions (United States)
2018-2022
Center for Independent Living
2021
Northrop Grumman (Germany)
2020
Georgia Institute of Technology
2011-2018
Massachusetts General Hospital
2014
Harvard University
2014
Lockheed Martin (Canada)
2013
This paper presents a novel computational approach to characterize hot-spot formations due impact in polymer-bonded explosives. As the shock propagates through grain/binder interfaces, subsequent mechanical and thermal processes lead localized temperature spikes that can contribute ignition of material transition detonation. Hot-spot characteristics are affected by small variations microstructure explosive, therefore require an accurate treatment wave propagation over sharp density...
For large-eddy simulation of turbulent premixed reacting flows, major challenges stem from the inability to resolve flame in a computationally affordable manner. These are most evident combustors characterized by large domains and thin flames. In these applications, thickened model may be used extend artificially numerically resolvable size through thickening factor. Thicker flames exhibit suppressed wrinkling presence turbulence, so an efficiency factor increases speed without influencing...
This paper focuses on improving the grid convergence properties of large-eddy simulations. To isolate impact numerical filtering and associated errors inherently present in implicitly filtered simulation approaches, authors have developed a novel explicit approach suitable for any mesh topology filter kernel. Simulations bluff-body stabilized, premixed flame configuration sequence meshes are used to demonstrate this methodology. Grid assessment is also performed another approach, wherein...
The individual pursuit is a 4-km cycling time trial performed on velodrome. Parathletes with transtibial amputation (TTA) have lost physiological systems, but this may be offset by the reduced aerodynamic drag of prosthesis. This research was to understand effect unilateral TTA Olympic performance. A forward-integration model performance explored interplay between power loss and gains in parathletes TTA. calibrated 4:10.5 (baseline), then adjusted account for Conditions simulated were based...
The vortical structures of recirculation zones in turbulent nonreacting and premixed reacting flows around confined equilateral-triangle bluff bodies are investigated using large-eddy simulations. A three-dimensional flow structure is observed within the cases; includes both “spanwise” vortices that extend length zone “corner vortex structures” situated adjacent to bluff-body trailing edge spanwise walls. corner enhance mixing residence times fluid inside zone. Fluid circulated between...
Summary The low Mach number performance of the MacCormack scheme is examined. inherent dissipation in found to suffer from degradation accuracy observed with traditional, density‐based methods for compressible flows. Two specific modifications are proposed, leading formation generalized within a dual‐time framework (called GMC‐PC). first modification involves reformulating flux by splitting it into particle convection and acoustic parts, former terms treated using traditional discretization...
This study investigates the sensitivity of turbulent-reacting large-eddy simulations (LESs) to seven ubiquitous modeling parameters. A forward-propagating uncertainty-quantification technique is applied chemistry–turbulence interaction and subgrid parameters through solution a bluff-body stabilized, premixed flame. Both implicit- explicit-filtering approaches are used for LES, providing insight into role in both approaches. Uniformly distributed ranges provided parameters, various levels...
The three-dimensional structure and dynamics of the recirculation zone downstream confined, bluff-body-stabilized, turbulent, premixed flames are examined numerically. Non-reacting reacting large eddy simulations performed on a truncated, periodic domain full-span with spanwise walls using two mesh resolutions. influence size, shape, intensity vortical structures in examined. non-reacting results show that while mean flow field is nominally uniform, turbulent statistics sensitive to choice...
The individual pursuit is a 4km cycling time trial performed on velodrome. cyclist must choose pacing strategy to produce the fastest given his/her physiological constraints. PURPOSE: To improve an energy flow model (de Koning, et. al., 1999, J Sci Med Sport) account for torque decay and mechanical involving forward integration (Martin, 2006, Sports Exerc.) better track geometry. Combine two models determine optimal cyclist. METHODS: One (75 kg, 1.83m, 32 y/o) was tested mean cadence during...
Residual and solution filtering procedures are studied with respect to inhibiting the accumulation of small-scale (i.e., high wavenumber) content. Assessing each method in terms an ``equivalent residual equation" reveals fundamental differences their behaviors, such as how underlying can be constrained a target filter width. The (RF) approach paired dissipative kernel is shown restrict scale generation fluid equations via dispersive effects; meanwhile, (SF) -- artificial dissipation (AD), by...
Large-scale corner vortex structures (CVS) are observed experimentally inside the recirculation zone of a confined, turbulent, premixed, two-dimensional bluff-body-stabilized flame. These counter-rotating CVS contribute to spanwise non-uniformity velocity field under reacting conditions but not present for non-reacting conditions. To investigate structure and dynamics CVS, experiments performed that vary fuel type (propane vs. natural gas), inlet velocity, preheat temperature, equivalence...
The propagation of uncertainty in chemical kinetics through laminar and turbulent flames is studied using an off-the-shelf quantification framework demonstrated with a hydrogen-oxygen flame. For the flames, flame speed ignition delay time as function equivalence ratio found to be dominated by single parameter corresponding chain reaction involving hydroxyl molecular hydrogen. Turbulent one-dimensional Linear-Eddy Model (LEM) at two different Reynolds numbers Thin-Reaction Zone Broken...
This paper presents a computational approach to characterize hot spot formations due impact in Polymer-Bonded Explosives (PBXs). As the shock propagates through grain/binder interfaces, subsequent mechanical and thermal processes lead localized temperature spikes that can ignite material transition detonation. Hot characteristics are affected by small variations micro-structure of sample therefore require an accurate treatment wave propagation over sharp density gradients. For this purpose,...
This study investigates the sensitivity of turbulent-reacting large-eddy simulations (LESs) to seven ubiquitous modeling parameters. A forward-propagating uncertainty-quantification technique is ap...