Download or read book Subfilter scale Turbulence Modeling for Large eddy Simulation of the Atmospheric Boundary Layer Over Complex Terrain written by Fotini Katopodes Chow and published by . This book was released on 2004 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Subgrid scale Turbulence Modeling for Improved Large eddy Simulation of the Atmospheric Boundary Layer written by Rica Mae Enriquez and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-eddy simulation (LES), as the name suggests, resolves the large eddies in the flow while modeling the effects of smaller motions (turbulence) on those larger eddies. Powerful computers make LES increasingly practical for analyzing a variety of atmospheric behavior in more detail, creating a need for more realistic turbulence models. Advances in describing atmospheric turbulence can impact many disciplines, e.g., weather and climate prediction, wind energy production, ocean dynamics, and, indeed, even computational fluid dynamics itself. Although the turbulence model can significantly affect the accuracy of the LES, simple turbulence models, which are known to be less accurate, are widely used. As an alternative, the Generalized Linear Algebraic Subgrid-Scale (GLASS) model, that actively couples momentum and heat transport, was developed. This model is more complete than conventional LES turbulence models because it accounts for additional transport processes. GLASS includes production, dissipation, pressure redistribution, and buoyancy terms. With the inclusion of an actively coupled turbulent heat flux model, GLASS is applicable to a range of atmospheric stability conditions for the unsaturated atmosphere. LES at various resolutions in a neutrally stratified boundary layer flow indicated that the GLASS model is a more physically complete subgrid-scale turbulence model that provides near-wall anisotropies and yields proper velocity profiles in the logarithmic layer. LES of the moderately convective boundary layer demonstrated that GLASS predicted the evolution of resolved quantities at least as well as the LESs with simple models, while including additional physics. Additional simulations of the stable boundary layer and the transitioning boundary layer highlight that GLASS can be applied to various stability conditions without the need of tuning model coefficients.

Download or read book Large eddy Simulation of the Nighttime Stable Atmospheric Boundary Layer written by Bowen Zhou and published by . This book was released on 2012 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: A stable atmospheric boundary layer (ABL) develops over land at night due to radiative surface cooling. The state of turbulence in the stable boundary layer (SBL) is determined by the competing forcings of shear production and buoyancy destruction. When both forcings are comparable in strength, the SBL falls into an intermittently turbulent state, where intense turbulent bursts emerge sporadically from an overall quiescent background. This usually occurs on clear nights with weak winds when the SBL is strongly stable. Although turbulent bursts are generally short-lived (half an hour or less), their impact on the SBL is significant since they are responsible for most of the turbulent mixing. The nighttime SBL can be modeled with large-eddy simulation (LES). LES is a turbulence-resolving numerical approach which separates the large-scale energy-containing eddies from the smaller ones based on application of a spatial filter. While the large eddies are explicitly resolved, the small ones are represented by a subfilter-scale (SFS) stress model. Simulation of the SBL is more challenging than the daytime convective boundary layer (CBL) because nighttime turbulent motions are limited by buoyancy stratification, thus requiring fine grid resolution at the cost of immense computational resources. The intermittently turbulent SBL adds additional levels of complexity, requiring the model to not only sustain resolved turbulence during quiescent periods, but also to transition into a turbulent state under appropriate conditions. As a result, LES of the strongly stable SBL potentially requires even finer grid resolution, and has seldom been attempted. This dissertation takes a different approach. By improving the SFS representation of turbulence with a more sophisticated model, intermittently turbulent SBL is simulated, to our knowledge, for the first time in the LES literature. The turbulence closure is the dynamic reconstruction model (DRM), applied under an explicit filtering and reconstruction LES framework. The DRM is a mixed model that consists of subgrid scale (SGS) and resolved subfilter scale (RSFS) components. The RSFS portion is represented by a scale-similarity model that allows for backscatter of energy from the SFS to the mean flow. Compared to conventional closures, the DRM is able to sustain resolved turbulence under moderate stability at coarser resolution (thus saving computational resources). The DRM performs equally well at fine resolution. Under strong stability, the DRM simulates an intermittently turbulent SBL, whereas conventional closures predict false laminar flows. The improved simulation methodology of the SBL has many potential applications in the area of wind energy, numerical weather prediction, pollution modeling and so on. The SBL is first simulated over idealized flat terrain with prescribed forcings and periodic lateral boundaries. A wide range of stability regimes, from weakly to strongly stable conditions, is tested to evaluate model performance. Under strongly stable conditions, intermittency due to mean shear and turbulence interactions is simulated and analyzed. Furthermore, results of the strongly stable SBL are used to improve wind farm siting and nighttime operations. Moving away from the idealized setting, the SBL is simulated over relatively flat terrain at a Kansas site over the Great Plains, where the Cooperative Atmospheric-Surface Exchange Study - 1999 (CASES-99) took place. The LES obtains realistic initial and lateral boundary conditions from a meso-scale model reanalysis through a grid nesting procedure. Shear-instability induced intermittency observed on the night of Oct 5th during CASES-99 is reproduced to good temporal and magnitude agreement. The LES locates the origin of the shear-instability waves in a shallow upwind valley, and uncovers the intermittency mechanism to be wave breaking over a standing wave (formed over a stagnant cold-air bubble) across the valley. Finally, flow over the highly complex terrain of the Owens Valley in California is modeled with a similar nesting procedure. The LES results are validated with observation data from the 2006 Terrain-Induced Rotor Experiment (T-REX). The nested LES reproduces a transient nighttime warming event observed on the valley floor on April 17 during T-REX. The intermittency mechanism is shown to be through slope-valley flow transitions. In addition, a cold-air intrusion from the eastern valley sidewall is simulated. This generates an easterly cross-valley flow, and the associated top-down mixing through breaking Kelvin-Helmholtz billows is analyzed. Finally, the nesting methodology tested and optimized in the CASES-99 and T-REX studies is transferrable to general ABL applications. For example, a nested LES is performed to model daytime methane plume dispersion over a landfill and good results are obtained.

Download or read book Large Eddy Simulations of Turbulence written by M. Lesieur and published by Cambridge University Press. This book was released on 2005-08-22 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large-Eddy Simulations of Turbulence is a reference for LES, direct numerical simulation and Reynolds-averaged Navier-Stokes simulation.

Download or read book Mountain Weather Research and Forecasting written by Fotini K. Chow and published by Springer Science & Business Media. This book was released on 2012-08-30 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides readers with a broad understanding of the fundamental principles driving atmospheric flow over complex terrain and provides historical context for recent developments and future direction for researchers and forecasters. The topics in this book are expanded from those presented at the Mountain Weather Workshop, which took place in Whistler, British Columbia, Canada, August 5-8, 2008. The inspiration for the workshop came from the American Meteorological Society (AMS) Mountain Meteorology Committee and was designed to bridge the gap between the research and forecasting communities by providing a forum for extended discussion and joint education. For academic researchers, this book provides some insight into issues important to the forecasting community. For the forecasting community, this book provides training on fundamentals of atmospheric processes over mountainous regions, which are notoriously difficult to predict. The book also helps to provide a better understanding of current research and forecast challenges, including the latest contributions and advancements to the field. The book begins with an overview of mountain weather and forecasting chal- lenges specific to complex terrain, followed by chapters that focus on diurnal mountain/valley flows that develop under calm conditions and dynamically-driven winds under strong forcing. The focus then shifts to other phenomena specific to mountain regions: Alpine foehn, boundary layer and air quality issues, orographic precipitation processes, and microphysics parameterizations. Having covered the major physical processes, the book shifts to observation and modelling techniques used in mountain regions, including model configuration and parameterizations such as turbulence, and model applications in operational forecasting. The book concludes with a discussion of the current state of research and forecasting in complex terrain, including a vision of how to bridge the gap in the future.

Download or read book Large eddy Simulation of Stably Stratified Atmospheric Boundary Layer Turbulence written by Sukanta Basu and published by . This book was released on 2004 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Large Eddy Simulation for Incompressible Flows written by P. Sagaut and published by Springer Science & Business Media. This book was released on 2006 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: First concise textbook on Large-Eddy Simulation, a very important method in scientific computing and engineering From the foreword to the third edition written by Charles Meneveau: "... this meticulously assembled and significantly enlarged description of the many aspects of LES will be a most welcome addition to the bookshelves of scientists and engineers in fluid mechanics, LES practitioners, and students of turbulence in general."

Download or read book Large eddy Simulation of the Development of Stably stratified Atmospheric Boundary Layers Over Cool Flat Surfaces written by and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The stable boundary layer (SBL) has received less attention in atmospheric field studies, laboratory experiments, and numerical modeling than other states of the atmospheric boundary layer. The low intensity and potential intermittency of turbulence in the SBL make it difficult to measure and characterize its structure. Large-eddy simulation (LES) offers an approach for simulating the SBL and, in particular, its evolution from the onset of surface cooling. Traditional approaches that involve Reynolds-averaged models of turbulence are not able to simulate the stochastic nature of the intermittent turbulence that is associated with the SBL. LES shows promise in this area through its explicit calculation of turbulent eddies at resolved scales. In the LES approach, the Navier-Stokes equations governing the flow are averaged (filtered) over some small interval, such as one or more cells of the computational grid. The grid size is small enough so that large eddies, which carry most of the turbulent energy, are explicitly calculated. The turbulence associated with the subgrid-scale (SGS) eddies is modeled. In the Reynolds-averaging approach, on the other hand, the turbulence model must account for all scales of turbulence. Thus the advantage of LES is that the choice of turbulence parameterization for the SGS turbulence is not nearly as critical as in the Reynolds-averaged approach. Complications faced by turbulence models, such as anisotropy and pressure-strain correlations, are associated mainly with large, energy-containing eddies. LES offers the potential for more realistic simulations since the more complicated features of turbulence are calculated explicitly. The ability of LES to simulate the stochastic behavior of turbulence makes this approach suitable for developing and testing stochastic models of turbulent diffusion. One of the goals of the present work is to provide stochastic datasets to be used in such studies.

Download or read book Conceptual Boundary Layer Meteorology written by April L. Hiscox and published by Academic Press. This book was released on 2022-08-27 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Conceptual Boundary Layer Meteorology: The Air Near Here explains essential boundary layer concepts in a way that is accessible to a wide number of people studying and working in the environmental sciences. It begins with chapters designed to present the language of the boundary layer and the key concepts of mass, momentum exchanges, and the role of turbulence. The book then moves to focusing on specific environments, uses, and problems facing science with respect to the boundary layer. Uses authentic examples to give readers the ability to utilize real world data Covers boundary layer meteorology without requiring knowledge of advanced mathematics Provides a set of tools that can be used by the reader to better understand land-air interactions Provides specific applications for a wide spectrum of environmental systems

Download or read book Dynamic Turbulence Modelling in Large Eddy Simulations of the Cloud Topped Atmospheric Boundary Layer written by M. P. Kirkpatrick and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of large eddy simulation, or LES, to study the atmospheric boundary layer dates back to the early 197Os when Deardorff (1972) used a three-dimensional simulation to determine velocity and temperature scales in the convective boundary layer. In 1974 he applied LES to the problem of mixing layer entrainment (Deardorff 1974) and in 1980 to the cloud-topped boundary layer (Deardorff 1980b). Since that time the LES approach has been applied to atmospheric boundary layer problems by numerous authors.

Download or read book Large Eddy Simulation of Stable Boundary Layer Turbulent Processes in Complex Terrain written by Eric D. Skyllingstad and published by . This book was released on 2005 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research was performed using a turbulence boundary layer model to study the behavior of cold, dense flows in regions of complex terrain. Results show that flows develop a balance between turbulent entrainment of warm ambient air and dense, cold air created by surface cooling. Flow depth and strength is a function of downslope distance, slope angle and angle changes, and the ambient air temperature.

Download or read book Direct and Large Eddy Simulation IV written by Bernard Geurts and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the proceedings of the 2001 DLES4 workshop. It describes and discusses state-of-the-art modeling and simulation approaches for complex flows. Fundamental turbulence and modeling issues but also elements from modern numerical analysis are at the heart of this field of interest.

Download or read book Direct and Large Eddy Simulation X written by Dimokratis G.E. Grigoriadis and published by Springer. This book was released on 2017-10-06 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses nearly all aspects of the state of the art in LES & DNS of turbulent flows, ranging from flows in biological systems and the environment to external aerodynamics, domestic and centralized energy production, combustion, propulsion as well as applications of industrial interest. Following the advances in increased computational power and efficiency, several contributions are devoted to LES & DNS of challenging applications, mainly in the area of turbomachinery, including flame modeling, combustion processes and aeroacoustics. The book includes work presented at the tenth Workshop on 'Direct and Large-Eddy Simulation' (DLES-10), which was hosted in Cyprus by the University of Cyprus, from May 27 to 29, 2015. The goal of the workshop was to establish a state of the art in DNS, LES and related techniques for the computation and modeling of turbulent and transitional flows. The book is of interest to scientists and engineers, both in the early stages of their career and at a more senior level.

Download or read book Similarity Models of Subfilter scale Energy and Temperature Variance for Large Eddy Simulations of the Atmospheric Boundary Layer written by Scott Thomas Salesky and published by . This book was released on 2010 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Large Eddy Simulation for Incompressible Flows written by Pierre Sagaut and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: First concise textbook on Large-Eddy Simulation, a very important method in scientific computing and engineering From the foreword to the third edition written by Charles Meneveau: "... this meticulously assembled and significantly enlarged description of the many aspects of LES will be a most welcome addition to the bookshelves of scientists and engineers in fluid mechanics, LES practitioners, and students of turbulence in general."

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2005 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book New Tools in Turbulence Modelling written by Olivier Metais and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical large-eddy simulation techniques are booming at present and will have a decisive impact on industrial modeling and flow control. The book represents the general framework in physical and spectral space. It also gives the recent subgrid-scale models. Topics treated include compressible turbulence research, turbulent combustion, acoustic predictions, vortex dynamics in non-trivial geometries, flows in nuclear reactors and problems in atmospheric and geophysical sciences. The book addresses numerical analysts, physicists, and engineers.