Download or read book A Radial Lagrangian Streamtube ensemble Modeling Approach and Its Applications to Reactive Transport Experiments in the Subsurface written by Jie Shang and published by . This book was released on 2003 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Upscaling Subsurface Reactive Transport with the Lamella Approach written by Ahmed Ali Mahmoud Ali and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Upscaling mixing-limited reactions is one of the ongoing problems in in-situ reactive transport within the groundwater due to the intrinsic challenges in characterizing such reactions. Previous techniques did not completely solve it; the classic macrodispersion (Eulerian) model overestimates the mixing and hence the reaction zone, while the Lagrangian particle tracking does not introduce a straightforward approach to evaluate the mixing zone extent, and also the streamtube technique does not capture the actual mixing zone and ignores the intra-tube mixing. The lamella approach is a new tool that overcomes the abovementioned shortcomings by decoupling the transport and reactions within a Lagrangian frame of reference tracking the reaction front only. The approach depends on dividing the mixing front (between displacing-displaced solutions) into approximately linear patches (lamellae, in 2-D) on which the mixing-limited reactions take place and are characterized in terms of transport impacts and reactions on them. Here the approach is applied to the 2-D radial flow for testing the equilibrium reaction network and the kinetic bimolecular reaction cases, also applied to the fractal radial domain to test the bimolecular equilibrium reaction. The theoretical reaction rate found via the simplified lamella approach is compared with explicit simulation using a finite elements (COMSOL) framework fitted with the representative multicomponent equilibrium reaction network and good matching is obtained implying the successfulness of the lamella tool.
Download or read book Lagrangian Modeling of Reactive Transport in Heterogeneous Porous Media written by Guillem Solé Marí and published by . This book was released on 2020 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid flow, solute transport, and chemical reactions in porous media are highly relevant for multiple applications and in several fields of knowledge. Aquifers are a typical example of porous media, but many others exist, like for instance biological tissues or wastewater treatment filters. Modeling and simulation of transport processes in porous media can be done through Lagrangian methods, which have certain advantages with respect to classical Eulerian methods. Among these advantages, a key one is that the solution of the advective transport term does not generate any numerical dispersion or instabilities, not even in those cases that are strongly dominated by advection, as opposed to what happens with classical Eulerian methods. However, the incorporation of chemical reaccions in the Lagrangian modeling context involves additional challenges and considerations with respect to conservative transport modeling. In this thesis, which is presented as a compendium of publications, new techniques are developed for modeling reactive transport of solutes in porous media from a Lagrangian perspective. Throghout the thesis, two different types of numerical particles are studied: mass-particles and fluid-particles. In both cases, continuum-scale dispersion (or at least part of it) is represented by random walks of numerical particles. Also in both cases, reactive transport simulations require interaction between nearby particles, either for directly computing reactions (when mass-particles are used) or for exchanging solutes (in the fluid-particle case). For this reason, a large part of this thesis revolves around the study of kernel functions, whose purpose is to mathematically represent the support volume of (and interaction between) particles. In this thesis it is shown that these functions, optimized using statistical theories of Kernel Density Estimation (KDE), may be used to simulate all kinds of nonlinear reactions with the mass-particle method known as Random Walk Particle Tracking (RWPT). Then, a new approach is developed for locally optimizing the particles' support volume (represented by the kernel bandwidth), such that it adapts its size and shape in time and space to minimize error. Thereafter, this technique is implemented in a hybrid manner in combination with a spatial discretization (binning) to improve its computational efficiency and to allow the incorporation of boundary conditions. Regarding fluid-particles, in this thesis it is shown that two methods that exist in Lagrangian modeling literature (Smoothed Particle Hydrodynamics or SPH, and Mass Transfer Particle Tracking) are mathematically equivalent, and they only differ in the choice of kernel used for the solute exchange between particles, which simulates dispersive transport. Finally, a novel Lagrangian fluid-particle method is developed, with an algorithm based on Multi-Rate Interaction by Exchange with the Mean (MRIEM), which enables to account for local-scale concentration fluctuation effects, as well as their generation, transport and decay. The method is shown capable of reproducing experimental results of reactive transport in a porous medium with locally mixing-limited conditions.
Download or read book Lagrangian Transport in Geophysical Jets and Waves written by Roger M. Samelson and published by Springer Science & Business Media. This book was released on 2006-11-24 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written jointly by a specialist in geophysical fluid dynamics and an applied mathematician, this is the first accessible introduction to a new set of methods for analysing Lagrangian motion in geophysical flows. The book opens by establishing context and fundamental mathematical concepts and definitions, exploring simple cases of steady flow, and touching on important topics from the classical theory of Hamiltonian systems. Subsequent chapters examine the elements and methods of Lagrangian transport analysis in time-dependent flows. The concluding chapter offers a brief survey of rapidly evolving research in geophysical fluid dynamics that makes use of this new approach.
Download or read book Reactive Transport Modeling Approach and Its Initial Saltcake Dilution Chemical Modeling written by Yasuo Onishi and published by . This book was released on 2002 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lagrangian Modeling of the Atmosphere written by John Lin and published by American Geophysical Union. This book was released on 2013-05-28 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 200. Trajectory-based (“Lagrangian”) atmospheric transport and dispersion modeling has gained in popularity and sophistication over the previous several decades. It is common practice now for researchers around the world to apply Lagrangian models to a wide spectrum of issues. Lagrangian Modeling of the Atmosphere is a comprehensive volume that includes sections on Lagrangian modeling theory, model applications, and tests against observations. Published by the American Geophysical Union as part of the Geophysical Monograph Series. Comprehensive coverage of trajectory-based atmospheric dispersion modeling Important overview of a widely used modeling tool Sections look at modeling theory, application of models, and tests against observations
Download or read book Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: DE-FG02-06ER64213: Development of Modeling Methods and Tools for Predicting Coupled Reactive Transport Processes in Porous Media at Multiple Scales Investigators: T. Prabhakar Clement (PD/PI) and Mark O. Barnett (Auburn), Chunmiao Zheng (Univ. of Alabama), and Norman L. Jones (BYU). The objective of this project was to develop scalable modeling approaches for predicting the reactive transport of metal contaminants. We studied two contaminants, a radioactive cation [U(VI)] and a metal(loid) oxyanion system [As(III/V)], and investigated their interactions with two types of subsurface materials, iron and manganese oxyhydroxides. We also developed modeling methods for describing the experimental results. Overall, the project supported 25 researchers at three universities. Produced 15 journal articles, 3 book chapters, 6 PhD dissertations and 6 MS theses. Three key journal articles are: 1) Jeppu et al., A scalable surface complexation modeling framework for predicting arsenate adsorption on goethite-coated sands, Environ. Eng. Sci., 27(2): 147-158, 2010. 2) Loganathan et al., Scaling of adsorption reactions: U(VI) experiments and modeling, Applied Geochemistry, 24 (11), 2051-2060, 2009. 3) Phillippi, et al., Theoretical solid/solution ratio effects on adsorption and transport: uranium (VI) and carbonate, Soil Sci. Soci. of America, 71:329-335, 2007.
Download or read book Particle and Streamline Numerical Methods for Conservative and Reactive Transport Simulations in Porous Media written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactive transport modeling has become an important tool to study and understand the transport and fate of solutes in the subsurface. However, the accurate simulation of reactive transport represents a formidable challenge because of the characteristics of flow, transport and chemical reactions that govern the migration of solutes in geological formations. In particular, solute transport in natural porous media is advection-controlled and dispersion is higher in the direction of flow than in the transverse direction. Both characteristics create difficulties for traditional numerical schemes that result in numerical dispersion and/or spurious oscillations. While these errors can often be tolerated in conservative transport simulations, they can be amplified in presence of chemical reactions resulting in much larger errors or unstable solutions. In this thesis, new Lagrangian based methods to simulate conservative and reactive transport in porous media are investigated. First, the derivation of a new meshless approximation based on smoothed particle hydrodynamics (SPH) to simulate conservative multidimensional solute transport, including advection and anisotropic dispersion, is presented. Second, a hybrid scheme that combines some of the advantages of streamline-based simulations and meshless methods and that allows simulating longitudinal and transverse dispersion without requiring a background grid is also derived. The numerical properties of both methods are analyzed analytical and numerically. Furthermore, both formulations are compared with existing numerical techniques in a set of two- and three-dimensional benchmark problems. It is demonstrated that the proposed schemes provide accurate and efficient solutions of physical transport processes in heterogeneous porous media and overcome most of the issues in existing numerical formulations. The new methods have the potential to remove or minimize numerical dispersion and grid orientation effects and, in the case o.
Download or read book The Lagrangian Stochastic Advective reactive Approach to Modeling Solute Transport in Hydrological Systems written by Archana Gupta and published by . This book was released on 2000 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Lagrangian Reactive Transport Simulator with Successive Paths and Stationary states written by R. B. Knapp and published by . This book was released on 1989 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: A geochemical software package which models static, single-path kinetic water-rock interactions, EQ3/6 [Wolery, 1979], has been modified to incorporate successive-paths and stationary states under high Peclet number transport conditions in a Lagrangian reference frame [Lichtner, 1988]. These modifications permit calculation of reactive transport with reasonable computational requirements. Results from the new option in EQ3/6 have been compared with analytical results for the simple HCl - SiO2 system; excellent agreements were achieved. Results have also been compared with published results [Lichtner, 1988] for a portion of the Al2O3 - HCl - K2O - SiO2 system. The results are in good qualitative and, in some cases, good quantitative agreement. However, the values of some variables differ substantially; these differences can be attributed to use of a different set of Al and Si aqueous species.
Download or read book A Lagrangian Reactive Transport Simulator with Successive Paths and Stationary states written by and published by . This book was released on 1989 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: A geochemical software package which models static, single-path kinetic water-rock interactions, EQ3/6 has been modified to incorporate successive-paths and stationary states under high Peclet number transport conditions in a Lagrangian reference frame. These modifications permit calculation of reactive transport with reasonable computational requirements. Results from the new option in EQ3/6 have been compared with analytical results for the simple HCl-SiO2 system; excellent agreements were achieved. Results have also been compared with published results for a portion of the Al2O3-HCl-K2O-SiO2 system. The results are in good qualitative and, in some cases, good quantitative agreement. However, the values of some variables differ substantially; these differences can be attributed to use of a different set of Al and Si aqueous species. 16 refs., 12 figs., 3 tabs.
Download or read book Smoothed Particle Hydrodynamics Model for Reactive Transport and Mineral Precipitation written by Paul Meakin and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A new Lagrangian particle model based on smoothed particle hydrodynamics was used to simulate pore scale precipitation reactions. The side-by-side injection of reacting solutions into two halves of a two-dimensional granular porous medium was simulated. Precipitation on grain surfaces occurred along a narrow zone in the middle of the domain, where the reacting solutes mixed to generate a supersaturated reaction product. The numerical simulations qualitatively reproduced the behavior observed in related laboratory experiments.
Download or read book Subsurface Multiphase Flow and Multicomponent Reactive Transport Modeling Using High Performance Computing written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical modeling has become a critical tool to the Department of Energy for evaluating the environmental impact of alternative energy sources and remediation strategies for legacy waste sites. Unfortunately, the physical and chemical complexity of many sites overwhelms the capabilities of even most "state of the art" groundwater models. Of particular concern are the representation of highly-heterogeneous stratified rock/soil layers in the subsurface and the biological and geochemical interactions of chemical species within multiple fluid phases. Clearly, there is a need for higher-resolution modeling (i.e. more spatial, temporal, and chemical degrees of freedom) and increasingly mechanistic descriptions of subsurface physicochemical processes. We present research being performed in the development of PFLOTRAN, a parallel multiphase flow and multicomponent reactive transport model. Written in Fortran90, PFLOTRAN is founded upon PETSc data structures and solvers and has exhibited impressive strong scalability on up to 4000 processors on the ORNL Cray XT3. We are employing PFLOTRAN in the simulation of uranium transport at the Hanford 300 Area, a contaminated site of major concern to the Department of Energy, the State of Washington, and other government agencies where overly-simplistic historical modeling erroneously predicted decade removal times for uranium by ambient groundwater flow. By leveraging the billions of degrees of freedom available through high-performance computation using tens of thousands of processors, we can better characterize the release of uranium into groundwater and its subsequent transport to the Columbia River, and thereby better understand and evaluate the effectiveness of various proposed remediation strategies.
Download or read book Reactive Transport in Soil and Groundwater written by Gunnar Nützmann and published by Springer Science & Business Media. This book was released on 2006-02-08 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, the authors focus on the improvement of the scientific base for the development of environmental risk indicators measured by the presence of pollutants in water and porous media. In pursuit of a correct and complete numerical approach, they deliver insight into the understanding of integrated process, and also of modeling capabilities.
Download or read book HST3D written by Kenneth L. Kipp and published by . This book was released on 1987 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Soil Physics Companion written by A.W. Warrick and published by CRC Press. This book was released on 2001-12-28 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: An authoritative reference on soil physics, Soil Physics Companion is lavishly illustrated with graphs, charts, line drawings, and equations. The book provides a valuable source of material and reference for most contemporary topics of soil physics and the vadose zone - arguably the most comprehensive volume available. In addition to being a reliab
Download or read book Air Water and Soil Quality Modelling for Risk and Impact Assessment written by Adolf Ebel and published by Springer Science & Business Media. This book was released on 2007-05-02 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the proceedings of the NATO Advanced Research Workshop on Air, Water and Soil Quality Modelling for Risk and Impact Assessment. The aim of the workshop was to further joint environmental compartment modelling and applications of control theory to environmental management. It provides an overview of ongoing research in this field regarding assessment of environmental risks and impacts.
