LONGITUDINAL SOLUTE TRANSPORT IN OPEN-CHANNEL FLOW - A Numerical Simulation Study on Longitudinal Dispersion, Surface Storage Effects, Transverse Mixing, Uncertainties and Parameter-Transferring Problems PDF Download

Author: Wei Zhang
Publisher:
ISBN:
Category : Civil engineering
Languages : en
Pages :

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Civil Engineering

Author: Kenneth E. Bencala
Publisher:
ISBN:
Category : Hydrodynamics
Languages : en
Pages : 66

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Author: Tongbi Tu
Publisher:
ISBN: 9780438930575
Category :
Languages : en
Pages :

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Solute transport in natural flows is a complex process, which is affected by various factors, such as channel roughness, river geometry, upstream inflow, lateral inflow, solute loadings. These factors are often spatiotemporally heterogeneous and uncertain. As a result, the solute transport process by rivers and stream flows in natural environment is full of uncertainties and has been approached as a stochastic process. Traditional transport governing equations are at point scale and cannot appropriately represent the stochastic dynamics of the transport process when applied in a reach scale or beyond. Upscaled governing equations of solute transport process in open channel flows are proposed in this dissertation to account for the uncertainties/heterogeneity in the transport process. One- and two-dimensional solute transport models are developed by upscaling the stochastic partial differential equations through their one-to-one correspondence to the nonlocal Lagrangian-Eulerian Fokker-Planck equations. The resulting Fokker-Planck equations are linear and deterministic differential equations, and these equations can provide a comprehensive probabilistic description of the spatiotemporal evolutionary probability distribution of the underlying solute transport process by one single numerical realization, rather than requiring thousands of simulations in the Monte Carlo simulation. Moreover, the proposed governing equations can explicitly indicate the effect of the corresponding drifts on the uncertainty of the transport process. Consequently, the ensemble behavior of the solute transport process can also be obtained based on the probability distribution. To illustrate the capabilities of the proposed stochastic solute transport models, various steady and unsteady uncertain flow and solute loading conditions are applied. The Monte Carlo simulation with stochastic flow and solute transport model is used to provide the stochastic flow field for the solute transport process, and further to validate the numerical solute transport results provided by the derived Fokker-Planck equations. The comparison of the numerical results by the Monte Carlo simulation and the Fokker-Planck equation approach indicates that the proposed models can adequately characterize the ensemble behavior of the solute transport process under uncertain flow and solute loading conditions via the evolutionary probability distribution in space and time of the transport process.

Author: E. C. Tsivoglou
Publisher:
ISBN:
Category : Stream self-purification
Languages : en
Pages : 344

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Author: Quanquan Liang
Publisher:
ISBN:
Category :
Languages : en
Pages : 83

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Longitudinal dispersivities are evaluated for two-dimensional open channel flow using a new velocity profile developed by Gomez (2006) as an alternative to the traditional "law of the wall" logarithmic profile commonly used. The modified profile improves on the logarithmic profile by incorporating a zero velocity gradient at the surface as well as a non-zero bottom slope, which is necessary for steady uniform flow. Non-dimensional forms of dispersivities are calculated based on Taylor's (1954) dispersivity equation using numerical integration with a polynomial approximation to enable integration of the indefinite integrals in that expression. While the velocities predicted by the traditional and modified profiles are relatively similar, significantly larger eddy viscosities are predicted with the new profile, and these are associated with slightly smaller longitudinal dispersivities. Flume experiments are performed to provide detailed velocity profile measurements, Reynolds stresses, and turbulent kinetic energy distributions. These data are used to compare the two profiles and to evaluate bottom shear stress and shear velocity for a range of conditions, and to provide a database for further research applications. The present results are meant to provide a stronger theoretical basis on which additional factors can be built for making final determinations of longitudinal dispersivity in the field. Further experiments are needed to directly measure longitudinal dispersivity and to confirm the present calculations.

Author: Sergio Eiger
Publisher:
ISBN:
Category : Diffusion in hydrology
Languages : en
Pages : 448

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ISBN:
Category :
Languages : en
Pages :

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Author: James L. Martin
Publisher: CRC Press
ISBN: 1351439871
Category : Technology & Engineering
Languages : en
Pages : 820

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Hydrodynamics and Transport for Water Quality Modeling presents a complete overview of current methods used to describe or predict transport in aquatic systems, with special emphasis on water quality modeling. The book features detailed descriptions of each method, supported by sample applications and case studies drawn from the authors' years of experience in the field. Each chapter examines a variety of modeling approaches, from simple to complex. This unique text/reference offers a wealth of information previously unavailable from a single source. The book begins with an overview of basic principles, and an introduction to the measurement and analysis of flow. The following section focuses on rivers and streams, including model complexity and data requirements, methods for estimating mixing, hydrologic routing methods, and unsteady flow modeling. The third section considers lakes and reservoirs, and discusses stratification and temperature modeling, mixing methods, reservoir routing and water balances, and dynamic modeling using one-, two-, and three-dimensional models. The book concludes with a section on estuaries, containing topics such as origins and classification, tides, mixing methods, tidally averaged estuary models, and dynamic modeling. Over 250 figures support the text. This is a valuable guide for students and practicing modelers who do not have extensive backgrounds in fluid dynamics.

Author: Andrew Francis Burke Tompson
Publisher:
ISBN:
Category : Porous materials
Languages : en
Pages : 114

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Author: Thomas Ritschel
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Research of solute transport fundamentally contributes to our understanding of soil functions as most processes in soils are dynamically driven and related to the transient conditions produced by the transport of solutes. For this reason, especially the transport of contaminants is frequently studied with laboratory scale column outflow experiments in an open-flow mode. This thesis presents a complementary approach of conducting saturated column experiments that is characterized by the recirculation of the effluent into the inflow via a mixing vessel and is therefore referred to as closed-flow mode column experiment. Depending on the ratio of the volume of the mixing vessel and the water-filled pore space, a damped oscillating concentration emerges in the effluent and in the mixing vessel. Oscillation frequency, damping and amplitude are thereby governed by the properties of the porous medium and the target substance. It was shown by column experiments with quartz sand that the appearance of oscillations can be controlled by using different mixing vessel solute volumes. The breakthrough data obtained within these experiments was then used to validate a numerical model that was derived by coupling the numerical solution of a transport equation with the model describing the mixing vessel in a loop. This model was used for a comprehensive sensitivity analysis to illustrate the response of the breakthrough curve to changes in the dispersion and the parameters describing adsorption with respect to strength, rate and nonlinearity. Each process thereby produced unique responses that confirm the high information content of closed-flow breakthrough data, which has shown to intrinsically contain information on the water content and the pumping rate as well. Finally, a numerical analysis of inverse parameter determination revealed a massive decrease in parameter uncertainty under optimal conditions, which renders the approach also highly relevant for practical applications.