Download or read book Dynamically Resolved Simulation of Atmospheric Features and Turbulence Using Advanced Models and Adaptive Algorithms written by David Scott McRae and published by . This book was released on 2005 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamically Resolved Simulation of Atmospheric Features and Turbulence Using Advanced Models and Adaptive Algorithms written by and published by . This book was released on 2008 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to resolve atmospheric features, such as gravity waves to the degree necessary for accurate optical turbulence prediction, we developed an adaptive version of MM5 that incorporates the NCSU Dynamic Solution Adaptive Grid Algorithm (DSAGA) and a new four-equation hybrid LES/RANS turbulence model that provides a new approach for the calculation of the index of refraction structure function Cn2, a quantitative measure of atmospheric optical turbulence. These four equations are used to model the turbulence kinetic energy, the variance of vorticity, the variance of potential temperature and its dissipation rate, respectively. The improvement in prediction of optical turbulence by the adaptive MM5 is documented by comparison with the models of Dewan and Jackson applied to unmodified MM5 output. By comparison with two sets of observations, the numerical results suggest that the adaptive MM5 Cn2 predictions approach binned observation variation in regions where the resolution has been improved by DSAGA, with little additional computational resources. However, predictions in both adaptive and fixed grid modes are degraded due to the fact that NWP codes, such as MM5, contain multiple types of numerical dissipation and in general use sponge layers at the upper boundary.
Download or read book Analysis of Inter scale Turbulence Chemistry Dynamics with Reduced Physics Simulations for Application to Large Eddy Simulation of Premixed Turbulent Combustion written by Paulo Lucena Kreppel Paes and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Large Eddy Simulation (LES) is a powerful formulation to model turbulent reacting flows with tradeoffs between complexity and resolution. The classical LES framework assumes that the evolution of the more energetic grid-filtered motions are dominated by the dynamical interactions that are explicitly resolved on an "effective grid" that incorporates implicit and/or explicit filtering at the smallest grid-resolvable scales by non-physical friction introduced by the numerical algorithm and modeled terms. The dynamical effects of the unresolved Sub-Filter-Scale (SFS) motions on the evolution of the Resolved-Scale (RS) motions are higher order modulations. However, the application of the classical LES framework to turbulent reacting flows is not clear since dynamically first-order chemical kinetics associated with heat release reside within mostly unresolved SFS thin flame regions. Consequently, key dynamics underlying the function of combustion devices often reside dominantly within unresolved SFS motions in contradiction to the fundamental requirement underlying accurate prediction of resolved-scale dynamics with LES. Furthermore, the topological structure of the flame is necessarily frontal in nature (i.e., sheet-like structure), which poses difficulties for an LES strategy that must model coherent structures that live partially in resolved and partially in subfilter scale fluctuations with a method that treats turbulence eddies as either resolved or subfilter scale. In my research program, we explore the introduction of new modeling elements embedded within current state-of-the-art LES frameworks to capture the impacts of the dynamically dominant inter-scale couplings between RS and SFS motions to improve the predictive accuracy of premixed turbulent combustion evolution at the resolved scales. We aim to systematically refine understanding of the inter-scale interactions between coherent structural features in physical space and in scale space in LES of premixed turbulent combustion. Given the complexity of the interaction between a flame and a complete range of turbulence eddy scales, we analyze reduced physics two-dimensional simulations of the interactions between single-scale vortex arrays and laminar premixed flames, with systematically increasing relative vortex strength creating higher complexity in flame corrugation. To characterize physical-scale space relationships, we apply the Fourier description using a newly developed procedure that removes the broadband Fourier spectral content associated with boundary discontinuities in the non-periodic directions of variables simulated within a finite domain without significant modification of the scales of interest in the original signals. This procedure allows for the analysis of any signal with the Fourier spectral decomposition regardless of the boundary conditions. Using Fourier-space filters, we identify characteristic coherent structural features concurrently in physical and Fourier space in response to flame-eddy interaction and their relative contributions to the SFS and RS variance content of the primary variables of interest. Momentum, energy and species concentrations display different distinct structural features that undergo systematic transition from weak to strong flame-vortex interactions. The primary variables within the dynamical system were classified based on the RS vs. SFS variance content, and distinct structural features in physical and Fourier space were identified for each class. We show that the SFS variance for all variables analyzed is associated with the SFS corrugated flame front, which in 2D Fourier space is associated with a coherent broadband "star-like" pattern that extends from the resolved to the flame subfilter scales. The directional dependences, magnitudes and phase relationships among the Fourier coefficients within the "legs" of the star reflect the power-law spectral representation of fronts and are shown to be closely connected with the direction and magnitude of flame-normal gradients of key variables within the corrugated flame front. We take advantage of the mathematical simplicity of the Fourier spectral description of the nonlinearities in the equations of motion to identify the dominant nonlinear couplings between SFS and RS fluctuations, and from these the SFS content involved in the dominant SFS-RS interactions. In Fourier space the nonlinear terms appear as sums of elemental scale interactions each of which have a well-defined geometrical relationship among wave vectors that form polygons in multidimensional Fourier space. Whereas the shape of the polygon is triangular within advective nonlinearities (triads), it is quadrangular for the chemical nonlinearities (quadrads). This elemental representation of key nonlinearities is used to develop a novel strategy to arrange and down-select the dominant nonlinear inter-scale couplings between SFS and RS motions, from which the corresponding SFS content associated with dynamically dominant RS-SFS dynamics are extracted. The procedure is applied to advective, triadic, and chemical, quadratic, nonlinearities within the LES-filtered governing equations. For primary variables that have most of its energy content at large scales and rapid drops in energy towards small scale, the large-scale features of the dynamically dominant SFS content are shown to be coupled with the smallest resolved scales leading to the corrugations and thickness of the RS flame front. In contrast, the dynamically dominant SFS content of intermediate species involved in heat release rate is shown to follow the smallest corrugations of the flame front reaction zone, which deviate from the RS flame centerline in regions with higher corrugations, such as the flame cusps. The distinct structural features of dynamically dominant SFS content are used for the development of simplified mathematical representations that could be applied within a modeling strategy that directly embeds the interaction between the modeled dominant SFS content and RS evolution within existing LES frameworks to improve the dynamical evolution of resolved-scale motions. From our analysis we develop a number of primary mathematical forms that encapsulate dominant SFS content of momentum, energy and key species variables within advective nonlinearities and show that these produce significant improvements in the time derivatives underlying evolution of the resolved scales. The analysis demonstrates the potential for incorporating directly key energetic and structural features of SFS that significantly impact the evolution of RS motions through key nonlinear dynamic couplings in LES frameworks employing highly simplified mathematical representations. This research lays the groundwork for a Galerkin-like modeling strategy that incorporates highly reduced numbers of basis functions that encapsulate previously determined dominant nonlinear couplings between subfilter-scale structure and resolved-scale evolution.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1997 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interstellar Turbulence written by José Franco and published by Cambridge University Press. This book was released on 1999-05-28 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This timely volume presents a series of review articles covering every aspect of interstellar turbulence--from accretion disks, molecular clouds, atomic and ionized media, through to spiral galaxies - based on a major international conference held in Mexico City.With advances in observational techniques and the development of more efficient computer codes and faster computers, research in this area has made spectacular progress in recent years. This book provides a comprehensive overview of the most important developments in observing and modelling turbulent flows in the cosmos. It provides graduate student and researchers with a state-of-the-art summary of observational, theoretical and computational research in interstellar turbulence.
Download or read book Towards Green Marine Technology and Transport written by Carlos Guedes Soares and published by CRC Press. This book was released on 2015-09-04 with total page 946 pages. Available in PDF, EPUB and Kindle. Book excerpt: Towards Green Marine Technology and Transport covers recent developments in marine technology and transport. The book brings together a selection of papers reflecting fundamental areas of recent research and development in the fields of ship hydrodynamics, marine structures, ship design, shipyard technology, ship machinery, maritime transportation,
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research Directions in Computational Mechanics written by National Research Council and published by National Academies Press. This book was released on 1991-02-01 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational mechanics is a scientific discipline that marries physics, computers, and mathematics to emulate natural physical phenomena. It is a technology that allows scientists to study and predict the performance of various productsâ€"important for research and development in the industrialized world. This book describes current trends and future research directions in computational mechanics in areas where gaps exist in current knowledge and where major advances are crucial to continued technological developments in the United States.
Download or read book Building Systems written by Leslie L. Christianson and published by . This book was released on 1989 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Symposium Papers, December 5-8, 1988, Allerton House, University of Illinois at Urbana-Champaign
Download or read book AIAA SDIO Annual Interceptor Technology Conference 92 2750 92 2775 written by and published by . This book was released on 1992 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1992 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2007 with total page 924 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Environmental Modeling written by Paolo Zannetti and published by Computational Mechanics. This book was released on 1996 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Atmospheric Sciences written by Board on Atmospheric Sciences and Climate and published by National Academies Press. This book was released on 1998-11-05 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technology has propelled the atmospheric sciences from a fledgling discipline to a global enterprise. Findings in this field shape a broad spectrum of decisions--what to wear outdoors, whether aircraft should fly, how to deal with the issue of climate change, and more. This book presents a comprehensive assessment of the atmospheric sciences and offers a vision for the future and a range of recommendations for federal authorities, the scientific community, and education administrators. How does atmospheric science contribute to national well-being? In the context of this question, the panel identifies imperatives in scientific observation, recommends directions for modeling and forecasting research, and examines management issues, including the growing problem of weather data availability. Five subdisciplines--physics, chemistry, dynamics and weather forecasting, upper atmosphere and near-earth space physics, climate and climate change--and their status as the science enters the twenty-first century are examined in detail, including recommendations for research. This readable book will be of interest to public-sector policy framers and private-sector decisionmakers as well as researchers, educators, and students in the atmospheric sciences.
Download or read book Journal of the Optical Society of America written by and published by . This book was released on 2001 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Performance Computing written by Heike Jagode and published by Springer Nature. This book was released on 2020-10-19 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed post-conference proceedings of 10 workshops held at the 35th International ISC High Performance 2020 Conference, in Frankfurt, Germany, in June 2020: First Workshop on Compiler-assisted Correctness Checking and Performance Optimization for HPC (C3PO); First International Workshop on the Application of Machine Learning Techniques to Computational Fluid Dynamics Simulations and Analysis (CFDML); HPC I/O in the Data Center Workshop (HPC-IODC); First Workshop \Machine Learning on HPC Systems" (MLHPCS); First International Workshop on Monitoring and Data Analytics (MODA); 15th Workshop on Virtualization in High-Performance Cloud Computing (VHPC). The 25 full papers included in this volume were carefully reviewed and selected. They cover all aspects of research, development, and application of large-scale, high performance experimental and commercial systems. Topics include high-performance computing (HPC), computer architecture and hardware, programming models, system software, performance analysis and modeling, compiler analysis and optimization techniques, software sustainability, scientific applications, deep learning.
Download or read book 43rd AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2005 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt:
