1,476 research outputs found
Employing per-component time step in DSMC simulations of disparate mass and cross-section gas mixtures
A new approach to simulation of stationary flows by Direct Simulation Monte
Carlo method is proposed. The idea is to specify an individual time step for
each component of a gas mixture. The approach consists of modifications mainly
to collision phase and recommendation on choosing time step ratios. It allows
softening the demands on the computational resources for cases of disparate
collision diameters of molecules and/or disparate molecular masses. These are
the cases important in vacuum deposition technologies. Few tests of the new
approach are made. Finally, the usage of new approach is demonstrated on a
problem of silver nanocluster diffusion in carrier gas argon in conditions of
silver deposition experiments.Comment: The goal of submission is to find native English speaker willing to
help me polish the paper. This is paper draft sent to Communications in
Computational Physics. It is recommended to publication. The need of
polishing was one of editors decision. See Additional data for MS Word source
fil
Optical measurement methods in thermogasdynamics
A review is presented of a number of optical methods of flow measurements. Consideration is given to such spectroscopic methods as emission and absorption techniques, electron beam-stimulated fluorescence, and light scattering - Rayleigh, Raman and Mie - methods. The following visualization methods are also discussed: shadow photography, schlieren photography, interferometry, holographic interferometry, laser anemometry, particle holography, and electron-excitation imaging. A large bibliography is presented and the work is copiously illustrated with figures and photographs
A Low Diffusion Particle Method for Simulating Compressible Inviscid Flows
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76416/1/AIAA-2007-4259-747.pd
Quantum Thermodynamics
Quantum thermodynamics is an emerging research field aiming to extend
standard thermodynamics and non-equilibrium statistical physics to ensembles of
sizes well below the thermodynamic limit, in non-equilibrium situations, and
with the full inclusion of quantum effects. Fuelled by experimental advances
and the potential of future nanoscale applications this research effort is
pursued by scientists with different backgrounds, including statistical
physics, many-body theory, mesoscopic physics and quantum information theory,
who bring various tools and methods to the field. A multitude of theoretical
questions are being addressed ranging from issues of thermalisation of quantum
systems and various definitions of "work", to the efficiency and power of
quantum engines. This overview provides a perspective on a selection of these
current trends accessible to postgraduate students and researchers alike.Comment: 48 pages, improved and expanded several sections. Comments welcom
National Aeronautics and Space Administration (NASA)/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program 1988, volume 1
The 1988 Johnson Space Center (JSC) National Aeronautics and Space Administration (NASA)/American Society for Engineering Education (ASEE) Summer Faculty Fellowship Program was conducted by the University of Houston and JSC. The 10-week program was operated under the auspices of the ASEE. The program at JSC, as well as the programs at other NASA Centers, was funded by the Office of University Affairs, NASA Headquarters, Washington, D.C. The objectives of the program, which began in 1965 at JSC and in 1964 nationally, are (1) to further the professional knowledge of qualified engineering and science faculty members; (2) to stimulate an exchange of ideas between participants and NASA; (3) to enrich and refresh the research and teaching activities of participants' institutions; and (4) to contribute to the research objectives of the NASA Centers
Challenges to Computational Aerothermodynamic Simulation and Validation for Planetary Entry Vehicle Analysis
Challenges to computational aerothermodynamic (CA) simulation and validation of hypersonic flow over planetary entry vehicles are discussed. Entry, descent, and landing (EDL) of high mass to Mars is a significant driver of new simulation requirements. These requirements include simulation of large deployable, flexible structures and interactions with reaction control system (RCS) and retro-thruster jets. Simulation of radiation and ablation coupled to the flow solver continues to be a high priority for planetary entry analyses, especially for return to Earth and outer planet missions. Three research areas addressing these challenges are emphasized. The first addresses the need to obtain accurate heating on unstructured tetrahedral grid systems to take advantage of flexibility in grid generation and grid adaptation. A multi-dimensional inviscid flux reconstruction algorithm is defined that is oriented with local flow topology as opposed to grid. The second addresses coupling of radiation and ablation to the hypersonic flow solver - flight- and ground-based data are used to provide limited validation of these multi-physics simulations. The third addresses the challenges of retro-propulsion simulation and the criticality of grid adaptation in this application. The evolution of CA to become a tool for innovation of EDL systems requires a successful resolution of these challenges
Director's discretionary fund report for fiscal year 1994
This technical memorandum contains brief technical papers describing research and technology development programs sponsored by the Ames Research Center Director's Discretionary Fund during fiscal year 1991 (October 1993 through September 1994). An appendix provides administrative information for each of the sponsored research programs
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