Theoretical Analysis and Large-eddy Simulations of the Propagation of Land-surface Heterogeneity in the Atmosphere PDF Download
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Author: Michael Hintz
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Languages : en
Pages : 0
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Author: Michael Hintz
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Category :
Languages : en
Pages : 0
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Author: Sreenath Paleri
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Category :
Languages : en
Pages : 0
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The Earth's surface is heterogeneous at multiple scales owing to spatial variability in various properties. The atmospheric responses to these heterogeneities through fluxes of energy, water, carbon, and other scalars are scale-dependent and nonlinear. Observational studies and large eddy simulations have observed secondary circulations in the turbulent atmospheric boundary layer as coherent turbulent structures or thermally induced mesoscale circulations. However, they have been limited in their ability to represent or quantify these events over realistic and heterogenous land surfaces. Chequamegon Heterogeneous Ecosystem Energy-balance Study Enabled by a High-density Extensive Array of Detectors (CHEESEHEAD) was a field campaign designed to intensively sample and scale land surface properties and the lower atmospheric response to it across a heterogeneous northern Wisconsin landscape.In this dissertation, airborne eddy covariance measurements were used to spatially resolve larger scale (meso-[beta], [gamma]) stationary/slow-moving eddies tied to landscape heterogeneity. We evaluate the mesoscale flux contributions by applying wavelet analysis to the airborne flux measurements during the campaign. Large Eddy Simulations (LES) of the field campaign days were set up with an interactive land surface model, coupled with a soil and plant canopy model. The land surface and plant canopy models were initialized and constrained by measurements taken during the field campaign to investigate surface atmospheric feedbacks. Secondary circulations induced due to the surface heterogeneities are diagnosed from the 3D LES data using time and ensemble averaging. The dynamical evolution of the circulations during the summer and fall test cases, with differing atmospheric boundary layer stabilities, is also discussed.
Author: John David Albertson
Publisher:
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Category :
Languages : en
Pages : 390
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Author: Boris Galperin
Publisher: Cambridge University Press
ISBN: 0521430097
Category : Technology & Engineering
Languages : en
Pages : 626
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Originally published in 1993, this book was the first to offer a comprehensive review of large eddy simulations (LES) - the history, state of the art, and promising directions for research. Among topics covered are fundamentals of LES; LES of incompressible, compressible, and reacting flows; LES of atmospheric, oceanic, and environmental flows; and LES and massivelt parallel computing. The book grew out of an international workshop that, for the first time, brought together leading researchers in engineering and geophysics to discuss developments and applications of LES models in their respective fields. It will be of value to anyone with an interest in turbulence modelling.
Author: Gongbing Peng
Publisher: Springer Science & Business Media
ISBN: 9783540674221
Category : Science
Languages : en
Pages : 500
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In this book the authors consider the natural environment as an integrated system. The physical, chemical and biological processes that govern the behaviour of the environmental system can thus be understood through mathematical modelling, and their evolution can be studied by means of numerical simulation. The book contains a summary of various efficient approaches in atmospheric prediction, such as numerical weather prediction and statistical forecast of climate change, as well as other successful methods in land surface modelling. The authors explore new theories and methods in environment prediction such as systems analysis and information theory. Attention is given to new achievements in remote sensing tele-metering and geographic information systems.
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Languages : en
Pages : 0
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The major objective of this study was to better understand the physical mechanisms involved in the dispersion of materials in the ABL that develops above heterogeneous land surfaces, using large eddy simulations This project consisted of three tasks: (i) An evaluation of our LES model against observations; (ii) A systematic analysis of the impact of microscale and meso-scale heat patches and topographical features on the structure of the ABL; and (iii) An analysis of the impact of these landscape heterogeneities on the dispersion of materials in the ABL. All three tasks have been fully completed. Using radiosondes, a network of surface fluxes. and a volume imaging lidar deployed in FIFE, we showed that, overall, the LES model performs quite well. However, its subgrid-scale parameterization needs to be improved to increase eddy dissipation. Various simulations using the FIFE data sets as well as ideal conditions indicate that microscale heterogeneities of surface heat fluxes and topographical features have only a minor to modest impact on the CBL, but can significantly affect the structure of turbulence. Meso-scale heterogeneities not only affect the structure of turbulence, but they can also significantly affect the mean characteristics of the CBL. These heterogeneities can also significantly affect the dispersion of materials. The results of this research were published in major peer-reviewed journals, and were presented at various professional meetings. A fourth and last year of funding was also provided to make a preliminary analysis of the ability of RAMS to simulate the stable nocturnal boundary layer (SNBL), in preparation of a more complete study on the dispersion of materials in this type of boundary layer. which will be proposed as a continuation of this completed project.
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Category : Aeronautics
Languages : en
Pages : 380
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Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: Maria Vittoria Salvetti
Publisher: Springer
ISBN: 3030049159
Category : Technology & Engineering
Languages : en
Pages : 562
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This book gathers the proceedings of the 11th workshop on Direct and Large Eddy Simulation (DLES), which was held in Pisa, Italy in May 2017. The event focused on modern techniques for simulating turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structures, as Direct Numerical Simulation (DNS), Large-Eddy Simulation (LES) or hybrid models based on a combination of LES and RANS approaches. In light of the growing capacities of modern computers, these approaches have been gaining more and more interest over the years and will undoubtedly be developed and applied further. The workshop offered a unique opportunity to establish a state-of-the-art of DNS, LES and related techniques for the computation and modeling of turbulent and transitional flows and to discuss about recent advances and applications. This volume contains most of the contributed papers, which were submitted and further reviewed for publication. They cover advances in computational techniques, SGS modeling, boundary conditions, post-processing and data analysis, and applications in several fields, namely multiphase and reactive flows, convection and heat transfer, compressible flows, aerodynamics of airfoils and wings, bluff-body and separated flows, internal flows and wall turbulence and other complex flows.
Author: Nick Shingleton
Publisher:
ISBN:
Category : Boundary layer (Meteorology)
Languages : en
Pages : 100
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Author: Peter R. Voke
Publisher: Springer Science & Business Media
ISBN: 9780792331063
Category : Technology & Engineering
Languages : en
Pages : 454
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Book Description
It is a truism that turbulence is an unsolved problem, whether in scientific, engin eering or geophysical terms. It is strange that this remains largely the case even though we now know how to solve directly, with the help of sufficiently large and powerful computers, accurate approximations to the equations that govern tur bulent flows. The problem lies not with our numerical approximations but with the size of the computational task and the complexity of the solutions we gen erate, which match the complexity of real turbulence precisely in so far as the computations mimic the real flows. The fact that we can now solve some turbu lence in this limited sense is nevertheless an enormous step towards the goal of full understanding. Direct and large-eddy simulations are these numerical solutions of turbulence. They reproduce with remarkable fidelity the statistical, structural and dynamical properties of physical turbulent and transitional flows, though since the simula tions are necessarily time-dependent and three-dimensional they demand the most advanced computer resources at our disposal. The numerical techniques vary from accurate spectral methods and high-order finite differences to simple finite-volume algorithms derived on the principle of embedding fundamental conservation prop erties in the numerical operations. Genuine direct simulations resolve all the fluid motions fully, and require the highest practical accuracy in their numerical and temporal discretisation. Such simulations have the virtue of great fidelity when carried out carefully, and repre sent a most powerful tool for investigating the processes of transition to turbulence.
