Download or read book Time Integration Algorithms for the Computer Treatment of the Horizontal Advection in Air Pollution Models written by Zahari Zlatev and published by . This book was released on 2018 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: The horizontal advection is one of the most important physical processes in an air pollution model. While it is clear how to describe mathematically this process, the computer treatment of the arising first-order partial differential equation (PDE) causes great difficulties. It is assumed that the spatial derivatives in this equation are discretized either by finite differences or by finite elements. This results in a very large system of ordinary differential equations (ODEs). The numerical treatment of this system of ODEs is based on the application of a set of predictor-corrector (PC) schemes with different absolute stability properties. The PC schemes can be varied during the time-integration. Schemes, which are computationally cheaper, are selected when the stability requirements are not stringent. If the stability requirements are stringent, then schemes that are more time-consuming, but also have better stability properties, are chosen. Some norms of the wind velocity vectors are calculated and used in the check of the stability requirements. Reductions of the time-step size are avoided (or, at least, reduced considerably) when the PC schemes are appropriately varied. This leads to an increase of the efficiency of the computations in the treatment of large-scale air pollution models. The procedure is rather general and can also be used in the computer treatment of other large-scale problems arising in different fields of science and engineering.
Download or read book Computer Treatment of Large Air Pollution Models written by Zahari Zlatev and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Models are often the only way of interpreting measurements to in vestigate long-range transport, and this is the reason for the emphasis on them in many research programs". B. E. A. Fisher: "A review of the processes and models of long-range transport of air pollutants", Atmospheric Environment, 17(1983), p. 1865. Mathematical models are (potentially, at least) powerful means in the efforts to study transboundary transport of air pollutants, source-receptor relationships and efficient ways of reducing the air pollution to acceptable levels. A mathematical model is a complicated matter, the development of which is based on the use of (i) various mechanisms describing mathematically the physical and chemical properties of the studied phenomena, (ii) different mathematical tools (first and foremost, partial differenti al equations), (iii) various numerical methods, (iv) computers (especially, high-speed computers), (v) statistical approaches, (vi) fast and efficient visualization and animation techniques, (vii) fast methods for manipulation with huge sets of data (input data, intermediate data and output data).
Download or read book Large Scale Scientific Computing written by Svetozar D. Margenov and published by Springer. This book was released on 2003-06-30 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the thoroughly refereed post-proceedings of the Third International Conference on Large-Scale Scientific Computing, LSSC 2001, held in Sozopol, Bulgaria, in June 2001. The 7 invited full papers and 45 selected revised papers were carefully reviewed for inclusion in the book. The papers are organized in topical sections on robust preconditioning algorithms, Monte-Carlo methods, advanced programming environments for scientific computing, large-scale computations in air pollution modeling, large-scale computations in mechanical engineering, and numerical methods for incompressible flow.
Download or read book Large Scale Computations in Air Pollution Modelling written by Zahari Zlatev and published by Springer Science & Business Media. This book was released on 1999-03-31 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the NATO Advanced Research Workshop, Sofia, Bulgaria, 6-10 July 1998
Download or read book Numerical Time Integration for Air Pollution Models written by Jan G. Verwer and published by . This book was released on 1998 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "Due to the large number of chemical species and the three space dimensions, off-the-shelf stiff ODE integrators are not feasible for the numerical time integration of stiff systems of advection-diffusion-reaction equations [formula] from the field of air pollution modelling. This has led to the use of special time integration techniques. This paper is devoted to a survey of such techniques, encompassing stiff chemistry solvers, positive advection schemes, time or operator splitting, implicit-explicit methods and approximate matrix factorization solutions. Of great importance in practice is high performance computing due to the huge problem scales, in particular for global models. We will therefore also report on experiences with vector/parallel shared memory and massively parallel distributed memory architectures and clusters of workstations. The survey is not entirely unique to air pollution models and biased towards work done at CWI over approximately the last 5 years."
Download or read book Air Pollution II written by J. M. Baldasano and published by Computational Mechanics. This book was released on 1994 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last decade has shown an increase in public and government concern around environmental issues due to air pollution, in particular those generated by man-made processes seeking the comfort of modern society. Atmospheric pollution consists of the adverse effects on the environment of a variety of substances (contaminants) emitted into the atmosphere by natural and man-made processes. These phenomena are complicated by the fact that an apparently inert contaminant can be transformed by chemical reaction into an adverse one, during its transport through the atmosphere.
Download or read book Computational Challenges in the Numerical Treatment of Large Air Pollution Models written by I. Dimov and published by . This book was released on 2018 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The air pollution, and especially the reduction of the air pollution to some acceptable levels, is an important environmental problem, which will become even more important in the next 10-20 years. This problem can successfully be studied only when high-resolution comprehensive models are developed and used on a routinely basis. However, such models are very time-consuming, also when modern high-speed computers are available. Indeed, if an air pollution model is to be applied on a large space domain by using fine grids, then its discretization will always lead to huge computational problems. Assume, for example, that the space domain is discretized by using a (480×480) grid and that the number of chemical species studied by the model is 35. Then several systems of ordinary differential equations containing 8064000 equations have to be treated at every time-step (the number of time-steps being typically several thousand). If a three-dimensional version of the same air pollution model is to be used, then the above figure must be multiplied by the number of layers. It is extremely difficult to treat such large computational problems; even when the fastest computers that are available at present are used.There is an additional great difficulty which is very often underestimated (or even neglected) when large application packages are moved from sequential computers to modern parallel machines. The high-speed computers have normally a very complicated memory architecture and, therefore, the task of producing an efficient code for the particular high-speed computer that is available is both extremely hard and very laborious.The use of standard parallelization tools in the solution of the problems sketched above is discussed in this paper. Results obtained on different types of parallel computers are given. It is demonstrated that the new efficient parallel algorithms allow us to solve more problems and bigger problems.
Download or read book An Implicit explicit Approach for Atmospheric Transport chemistry Problems written by Jan G. Verwer and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "We investigate numerical algorithms for use in air pollution models. The emphasis lies on time integration aspects in connection with advection, vertical turbulent diffusion and stiff chemical transformations. The time integration scheme considered is a 2nd-order implicit-explicit BDF scheme which handles advection explicitly and vertical turbulent diffusion and chemistry implicitly and coupled. The investigation is divided into three parts. In the first part we propose a Gauss-Seidel technique for the implicit solution of the chemistry and vertical turbulent diffusion. For a hypothetical 1D model, based on a 66- species EMEP photochemical ozone chemistry scheme, this technique is shown to be significantly more efficient than the usual approach of using modified Newton with a linear band solver. For the stiff chemistry the Gauss-Seidel iteration is effectively explicit. For the diffusion the implicitness is retained, which gives rise to tridiagonal linear systems. In the second part we discuss stability and consistency properties of the implicit-explicit BDF scheme, assuming the 3rd-order upwind biased finite- difference discretization of the advection operator. In the third part we apply the implicit-explicit scheme to a hypothetical 3D model based on the same photochemical ozone chemistry. Here we employ vectorization over the horizontal grid. Grid-vectorization is of large practical interest as it leads to significantly higher efficiency on a vector computer. Dependent of the process at hand, parallelization is obtained either over the horizontal or over the vertical grid."
Download or read book Development of Advection Algorithms in Air Quality Models written by Khoi Huu Nguyen and published by . This book was released on 1999 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Atmospheric Chemistry written by Guy P. Brasseur and published by Cambridge University Press. This book was released on 2017-06-19 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematical modeling of atmospheric composition is a formidable scientific and computational challenge. This comprehensive presentation of the modeling methods used in atmospheric chemistry focuses on both theory and practice, from the fundamental principles behind models, through to their applications in interpreting observations. An encyclopaedic coverage of methods used in atmospheric modeling, including their advantages and disadvantages, makes this a one-stop resource with a large scope. Particular emphasis is given to the mathematical formulation of chemical, radiative, and aerosol processes; advection and turbulent transport; emission and deposition processes; as well as major chapters on model evaluation and inverse modeling. The modeling of atmospheric chemistry is an intrinsically interdisciplinary endeavour, bringing together meteorology, radiative transfer, physical chemistry and biogeochemistry, making the book of value to a broad readership. Introductory chapters and a review of the relevant mathematics make this book instantly accessible to graduate students and researchers in the atmospheric sciences.
Download or read book Numerical Treatment of Time Dependent Advection and Diffusion of Air Pollutants written by E. Runca and published by . This book was released on 1974 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1984 with total page 986 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Air Pollution Modeling written by P. Zannetti and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finishing this book is giving me a mixture of relief, satisfaction and frus tration. Relief, for the completion of a project that has taken too many of my evenings and weekends and that, in the last several months, has become almost an obsession. Satisfaction, for the optimistic feeling that this book, in spite of its many shortcomings and imbalances, will be of some help to the air pollution scientific community. Frustration, for the impossibility of incorporating newly available material that would require another major review of several key chap ters - an effort that is currently beyond my energies but not beyond my desires. The first canovaccio of this book came out in 1980 when I was invited by Computational Mechanics in the United Kingdom to give my first Air Pollution Modeling course. The course material, in the form of transparencies, expanded, year after year, thus providing a growing working basis. In 1985, the ECC Joint Research Center in Ispra, Italy, asked me to prepare a critical survey of mathe matical models of atmospheric pollution, transport and deposition. This support gave me the opportunity to prepare a sort of "first draft" of the book, which I expanded in the following years.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1973 with total page 1064 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Weather and Climate Prediction written by Thomas Tomkins Warner and published by Cambridge University Press. This book was released on 2010-12-02 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook provides a comprehensive yet accessible treatment of weather and climate prediction, for graduate students, researchers and professionals. It teaches the strengths, weaknesses and best practices for the use of atmospheric models. It is ideal for the many scientists who use such models across a wide variety of applications. The book describes the different numerical methods, data assimilation, ensemble methods, predictability, land-surface modeling, climate modeling and downscaling, computational fluid-dynamics models, experimental designs in model-based research, verification methods, operational prediction, and special applications such as air-quality modeling and flood prediction. This volume will satisfy everyone who needs to know about atmospheric modeling for use in research or operations. It is ideal both as a textbook for a course on weather and climate prediction and as a reference text for researchers and professionals from a range of backgrounds: atmospheric science, meteorology, climatology, environmental science, geography, and geophysical fluid mechanics/dynamics.
Download or read book Computational and Numerical Challenges in Environmental Modelling written by Zahari Zlatev and published by Elsevier. This book was released on 2006-05-02 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many large mathematical models, not only models arising and used in environmental studies, are described by systems of partial differential equations. The discretization of the spatial derivatives in such models leads to the solution of very large systems of ordinary differential equations. These systems contain many millions of equations and have to be handled over large time intervals by applying many time-steps (up to several hundred thousand time-steps). Furthermore, many scenarios are as a rule to be run. This explains the fact that the computational tasks in this situation are enormous. Therefore, it is necessary to select fast numerical methods; to develop parallel codes and, what is most important when the problems solved are very large to organize the computational process in a proper way.The last item (which is very often underestimated but, let us re-iterate, which is very important) is the major topic of this book. In fact, the proper organization of the computational process can be viewed as a preparation of templates which can be used with different numerical methods and different parallel devices. The development of such templates is described in the book. It is also demonstrated that many comprehensive environmental studies can successfully be carried out when the computations are correctly organized. Thus, this book will help the reader to understand better that, while (a) it is very important to select fast numerical methods as well as (b) it is very important to develop parallel codes, this will not be sufficient when the problems solved are really very large. In the latter case, it is also crucial to exploit better the computer architecture by organizing properly the computational process. - Use of templates in connection with the treatment of very large models - Performance of comprehensive environmental studies - Obtaining reliable and robust information about pollution levels - Studying the impact of future climatic changes on high pollution levels - Investigating trends related to critical levels of pollution
Download or read book Joint Conference on Applications of Air Pollution Meteorology written by and published by . This book was released on 1988 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:
