Description Of Hydrodynamic Processes Research Articles

Effects of dimensionality on the performance of hydrodynamic models for stratified lakes and reservoirs

Abstract. Numerical models are an important tool for simulating temperature, hydrodynamics, and water quality in lakes and reservoirs. Existing models differ in dimensionality by considering spatial variations of simulated parameters (e.g., flow velocity and water temperature) in one (1D), two (2D) or three (3D) spatial dimensions. The different approaches are based on different levels of simplification in the description of hydrodynamic processes and result in different demands on computational power. The aim of this study is to compare three models with different dimensionalities and to analyze differences between model results in relation to model simplifications. We analyze simulations of thermal stratification, flow velocity and substance transport by density currents in a medium-sized drinking-water reservoir in the subtropical zone, using three widely used open-source models: GLM (1D), CE-QUAL-W2 (2D) and Delft3D (3D). The models were operated with identical initial and boundary conditions over a 1-year period. Their performance was assessed by comparing model results with measurements of temperature, flow velocity and turbulence. Our results show that all models were capable of simulating the seasonal changes in water temperature and stratification. Flow velocities, only available for the 2D and 3D approaches, were more challenging to reproduce, but 3D simulations showed closer agreement with observations. With increasing dimensionality, the quality of the simulations also increased in terms of error, correlation and variance. None of the models provided good agreement with observations in terms of mixed layer depth, which also affects the spreading of inflowing water as density currents and the results of water quality models that build on outputs of the hydrodynamic models.

Математическое описание гидродинамических процессов в условиях нелинейной фильтрации. Критические градиенты давления

Математическое описание гидродинамических процессов в условиях нелинейной фильтрации. Критические градиенты давления

Review of Hydrodynamics and Water Quality: Modeling Rivers, Lakes, and Estuaries by Zhen-Gang JiHydrodynamics and Water Quality: Modeling Rivers, Lakes, and EstuariesWiley Interscience, John Wiley & Sons, Inc.978-0-470-13543-3

Management of surface water systems, including rivers, reservoirs, lakes, wetlands, and estuaries, requires technical tools that must be based on physical, chemical, biological, and social sciences. Some of these tools entail numerical hydrodynamic and water quality models, made possible these days by everincreasing computing prowess. This book attempts to describe physical, chemical, and biological concepts underlying these models. To that end, the book aims at providing an integrated treatment of hydrodynamics, sediment transport and processes, toxic fate and transport, water quality, and eutrophication in surface water systems. The emphasis in the book is on principles, basic processes, mathematical descriptions, and practical applications via case studies. Justifiably, it avoids long mathematical derivations. The book also presents case studies to illustrate the implementation of basic concepts and theories and technical approaches based thereon into mathematical models, as well as application of these models to address practical environmental and water resources problems. The subject matter of the book is logically divided into 10 chapters and three appendices. Chapter 1 provides an overview and develops the context for the material to be described in the book. Chapter 2 provides basic concepts and principles of hydrodynamics. Starting with a description of hydrodynamic processes, it goes on to discuss governing equations and their approximations in one-dimensional, two-dimensional and three-dimensional Cartesian coordinates. Equations in curvilinear coordinates are presented next, followed by a discussion of initial and boundary conditions. Then temperature and heat fluxes are presented. This discussion is integrated in the following section on hydrodynamic modeling, with case studies of Lake Ockeechobee and the St. Lucie Estuary and Indian River Lagoon. These case studies are very helpful to understand hydrodynamics and its practical application. Sediment transport is discussed in Chapter 3. Providing an overview, including sediment properties, problems associated with sediment, and sediment processes, it discusses sediment transport equations for both cohesive and noncohesive sediments, as well as wind waves and their impact on sediment transport. The chapter presents two case studies one on wind wave modeling and the other on sediment transport modeling in Lake Ockeechobee. The third case study is on sediment transport modeling for Blackstone River. These case studies clearly show how to set up a model, define initial and boundary conditions, prepare data