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Finite Element Simulation in Surface and Subsurface Hydrology provides an introduction to the finite element method and how the method is applied to problems in surface and subsurface hydrology. The book presents the basic concepts of the numerical methods and the finite element approach; applications to problems on groundwater flow and mass and energy transport; and applications to problems that involve surface water dynamics. Computational methods for the solution of differential equations; classification of partial differential equations; finite difference and weighted residual integral techniques; and The Galerkin finite element method are discussed as well. The text will be of value to engineers, hydrologists, and students in the field of engineering.
The mixed explicit-implicit Galerkin finite element method developed previously by the authors is shown to be ideally suited for a wide class of problems arising in subsurface hydrology. These problems include confined saturated flow, unconfined flaw under free surface conditions subject to the Dupuit assumption, flow in aquifers which are partly confined and partly unconfined, axisymmetric flow to a well with storage, and flow in saturated-unsaturated soils. A single computer program, entitled FLUMP, can now handle all of these problems. The mixed explicit-implicit solution strategy employed in the program insures a high level of accuracy and computation efficiency in most cases. It eliminates many of the difficulties that groundwater hydrologists have been encountering in trying to simulate extensive aquifer systems by finite elements. Some of the outstanding features of this solution strategy include an automatic control of time step size, reclassification of nodes from explicit to implicit during execution, automatic adjustment of the implicit time weighting factor, and the treatment of boundary conditions and source terms as arbitrary functions of time of the state of the system. Five examples are presented to demonstrate the versatility and power of this new approach. A purely physical derivation of the finite element equations which does not rely on the Galerkin formalism is also included in one of the appendices.
Computational Subsurface Hydrology: Fluid Flows offers practicing engineers and scientists a theoretical background, numerical methods, and computer codes for the modeling of fluid flows in subsurface media. It will also serve as a text for senior and graduate courses on fluid flows in subsurface media in disciplines such as civil and environmental engineering, agricultural engineering, geosciences, soil sciences, and chemical engineering. Computational Subsurface Hydrology: Fluid Flows presents a systematic derivation of governing equations and boundary conditions of subsurface fluid flow. It discusses a variety of numerical methods, expounds detailed procedures for constructing finite element methods, and describes precise implementation of computer codes as they are applied to subsurface flows. Four computer codes to simulate vertically integrated horizontal flows (FEWA), saturated flows with moving phreatic surfaces in three dimensions (3DFEWA), variably saturated flows in two dimensions (FEMWATER), and variable flows in three dimensions (3DFEMWATER) are attached to this book. These four computer codes are designed for generic applications to both research and practical problems. They could be used to simulate most of the practical, real-world field problems. If you would like a copy of the diskettes containing the four, basic general purpose computer codes referred to in Computational Subsurface Hydrology: Fluid Flows, please email Gour-Tsyh Yeh at the following address : [email protected]
This book is the edited proceedings of the Fifth International Conference on Finite Elements in Water Resources, held at the University of Vermont, USA in June 1984. This Conference cont inues the successful series started at Princeton University in 1976, followed by the Conference in Imperial College, London, UK in 1978, the third Conference at the University of Mississippi, USA in 1980 and the fourth at the University of Hannover, Germany in 1982. The objective of this Conference is to provide engineers and scientists interested in water resources with the state-of-t- art on finite element modelling. The Proceedings review the basic theory and applications of the technique in groundwater and seepage, transport phenomena, viscous flow, river, lake and ocean modelling. The fundamentals of the numerical techniques employed in finite elements are also discussed. Many applications illus trate the versatility and generality of the Finite Element Method for the simulation of a wide range of problems in water resources. More recent schemes, in particular, boundary elements, are also presented, together with a series of advanced numerical techniques. The Conference has become an internationally accepted forum for the presentation of new developments of finite elements in water resources techniques. Because of this, a large number of abstracts were submitted to the Organizing Committee and it is our only reg ret that it was impossible to accept all these contributions. The overwhelming response to our Call for Papers has ensured the high quality of these proceedings.
FEFLOW is an acronym of Finite Element subsurface FLOW simulation system and solves the governing flow, mass and heat transport equations in porous and fractured media by a multidimensional finite element method for complex geometric and parametric situations including variable fluid density, variable saturation, free surface(s), multispecies reaction kinetics, non-isothermal flow and multidiffusive effects. FEFLOW comprises theoretical work, modeling experiences and simulation practice from a period of about 40 years. In this light, the main objective of the present book is to share this achieved level of modeling with all required details of the physical and numerical background with the reader. The book is intended to put advanced theoretical and numerical methods into the hands of modeling practitioners and scientists. It starts with a more general theory for all relevant flow and transport phenomena on the basis of the continuum approach, systematically develops the basic framework for important classes of problems (e.g., multiphase/multispecies non-isothermal flow and transport phenomena, discrete features, aquifer-averaged equations, geothermal processes), introduces finite-element techniques for solving the basic balance equations, in detail discusses advanced numerical algorithms for the resulting nonlinear and linear problems and completes with a number of benchmarks, applications and exercises to illustrate the different types of problems and ways to tackle them successfully (e.g., flow and seepage problems, unsaturated-saturated flow, advective-diffusion transport, saltwater intrusion, geothermal and thermohaline flow).
Any numerical subsurface model is comprised of three components: a theoretical basis to translate our understanding phenomena into partial differential equations and boundary conditions, a numerical method to approximate these governing equations and implement the boundary conditions, and a computer implementation to generate a generic code for research as well as for practical applications. Computational Subsurface Hydrology: Reactions, Transport, and Fate is organized around these themes. The fundamental processes occurring in subsurface media are rigorously integrated into governing equations using the Reynolds transport theorem and interactions of these processes with the surrounding media are sophisticatedly cast into various types of boundary conditions using physical reasoning. A variety of numerical methods to deal with reactive chemical transport are covered in Computational Subsurface Hydrology: Reactions, Transport, and Fate with a particular emphasis on the adaptive local grid refinement and peak capture using the Lagrangian-Eulerian approach. The topics on coupled fluid flows and reactive chemical transport are unique contributions of this book. They serve as a reference for research as well as for practical applications with a computer code that can be purchased from the author. Four computer codes to simulate vertically integrated horizontal solute transport (LEMA), contaminant transport in moving phreatic aquifers in three dimensions (3DLEMA), solute transport in variably saturated flows in two dimensions (LEWASTE), and solute transport under variably saturated flows in three dimensions (3DLEWASTE) are covered. These four computer codes are designed for generic applications to both research and practical problems. They could be used to simulate most of the practical, real-world field problems. Reactive chemical transport and its coupling with fluid flows are unique features in this book. Theories, numerical implementations, and example problems of coupled reactive transport and flows in variably saturated media are presented. A generic computer code, HYDROGEOCHEM 3.0, is developed. A total of eight example problems are used to illustrate the application of the computational model. These problems are intended to serve as examples for setting up a variety of simulations that one may encounter in research and field-site applications. Computational Subsurface Hydrology: Reactions, Transport, and Fate offers practicing engineers and scientists a theoretical background, numerical methods, and computer codes for modeling contaminant transport in subsurface media. It also serves as a textbook for senior and graduate course on reactive chemical transport in subsurface media in disciplines such as civil and environmental engineering, agricultural engineering, geosciences, soil sciences, and chemical engineering. Computational Subsurface Hydrology: Reactions, Transport, and Fate presents a systematic derivation of governing equations and boundary conditions of subsurface contaminant transport as well as reaction-based geochemical and biochemical processes. It discusses a variety of numerical methods for moving sharp-front problems, expounds detail procedures of constructing Lagrangian-Eulerian finite element methods, and describes precise implementation of computer codes as they are applied to subsurface contaminant transport and biogeochemical reactions.