Download or read book Two phase Flow Modeling of Suspended Sediment Transport written by Blair Powell Greimann and published by . This book was released on 1998 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical and Numerical Modeling of Suspended Sediment Transport in Open Channels Using an Eulerian Eulerian Two phase Flow Approach written by Sanjeev Kumar Jha and published by . This book was released on 2009 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Multi dimensional Two phase Flow Modeling Framework for Sediment Transport Applications written by Zhen Cheng and published by . This book was released on 2016 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studying coastal processes is essential for the sustainability of human habitat and vibrancy of coastal economy. Coastal morphological evolution is caused by a wide range of coupled cross-shore and alongshore sediment transport processes associated with short waves, infra-gravity waves, and wave-induced currents. One of the key challenges was that the major transport occurs within bottom boundary layers and it is dictated by turbulence-sediment interactions and inter-granular interactions. Therefore, this study focuses on numerical investigations of sediment transport in the bottom wave boundary layers on continental shelves and nearshore zones, with emphasis on both fine sediment (mud) and sand transports. On the continental shelves, the sea floor is often covered with fine sediments (with settling velocity no more than a few mm/s). Wave-induced resuspension has been identified as one of the major mechanisms in the offshore delivery for fine sediments. A series of turbulence-resolving simulations were carried out to study the role of sediment resuspension/deposition on the bottom sediment transport. Specifically, we focus on how the critical shear stress of erosion and the settling velocity can determine the transport modes. At a given wave intensity associated with more energetic muddy shelves, three transport modes, namely the well-mixed transport (mode I), two-layer like transport with the formation of lutocline (mode II) and laminarized transport (mode III), are obtained by varying the critical shear stress of erosion or the settling velocity. A 2D parametric map is proposed to characterize the transition between transport modes as a function of the critical shear stress and the settling velocity at a fixed wave intensity. In addition, the uncertainties due to hindered settling and particle inertia effects on the transport modes were further studied. Simulation results confirmed that the effect of particle inertia is negligible for fine sediment in typical wave condition on continental shelves. On the other hand, the hindered settling with low gelling concentration can play a key role in sustaining a large amount of suspended sediments and results in the laminarized transport (mode III). Low gelling concentrations can also trigger the occurrence of gelling ignition, a state in which the erosion rate always exceeds the deposition rate. A sufficient condition for the occurrence of gelling ignition is hypothesized for a range of wave intensities as a function of sediment/floc properties and erodibility parameters. In the more energetic nearshore zones, the sea floor is often covered with sand (with settling velocity exceeds 1 cm/s). Based on the open-source CFD toolbox OpenFOAM, a multi-dimensional Eulerian two-phase modeling framework is developed for sediment transport applications. With closures of particle stresses and fluid-particle interactions, the model is able to resolve full sediment transport profiles without conventional bedload/suspended load assumptions. The turbulence-averaged model is based on a modified k-epsilon closure for the carrier flow turbulence and it was used to study momentary bed failure under sheet flow conditions. Model results revealed that the momentary bed failure and the resulting large transport rate were associated with a large erosion depth, which was triggered by the combination of large bed shear stresses and large horizontal pressure gradients. In order to better resolve turbulence-sediment interactions, the modeling framework was also extended with a 3D turbulence-resolving capability, where most of the turbulence-sediment interactions are directly resolved. The model is validated against a steady sheet flow experiment for coarse light particles. It is found that the drag-induced turbulence damping effect was more significant than the well-known density stratification for the flow condition and grain properties considered. Meanwhile, the turbulence-resolving model is able to reproduce bed intermittency, which was driven by turbulent ejection and sweep motions, similar to the laboratory observation. Finally, simulations for fine sand transport in oscillatory sheet flow demonstrate that the turbulence-resolving model is able to capture the enhanced transport layer thickness for fine sand, which may be related to the burst events near flow reversal. Several future research directions, including further improvements of the present modeling framework and science issues that may be significantly benefited from the present turbulence-resolving sediment transport framework, are recommended.
Download or read book An Evaluation of Modeling Sediment Transport as a Two Phase Flow written by Mahesh Lokare and published by . This book was released on 1995 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling Sediment Transport Using a Two phase Flow Approach written by Leslie J.C. Aquino and published by . This book was released on 2001 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Two phase Flow Approach for Sediment Transport written by Tian-Jian Hsu and published by . This book was released on 2002 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sedimentation and Sediment Transport written by A. Gyr and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is evident, that for a number of ecological and technical problems in rivers and lakes a better knowledge of sediment transport and sedimentation is needed together with the ability to predict and simulate sediment behaviour. On the other hand, a stagnation of research in these topics could be observed in the last decades. At the Symposium an attempt was made to present new results in mathematics and natural sciences relevant for the sediment problem. New strategies were discussed to tackle the complexity of the problem. Basic theoretical research and laboratory experiments alone are incomplete without a feedback from field observations and measurements. For that reason well-known researchers from both basic and engineering sciences were invited. Turbulence, non-local phenomena, stability, interaction, feedback systems, self-organization, two-phase flow and chaotic processes, numerical simulations as well as measurement techniques and field results were the keywords of the Symposium. This proceedings are a good source for those interested in the state of the art.
Download or read book Numerical Modeling of Sediment Transport Near the Bed Using a Two phase Flow Approach written by Andrea Emilia Gonzalez and published by . This book was released on 2008 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling and Practice of Erosion and Sediment Transport under Change written by Mohamed Meddi and published by MDPI. This book was released on 2019-09-17 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Climate and anthropogenic changes impact the conditions of erosion and sediment transport in rivers. Rainfall variability and, in many places, the increase of rainfall intensity have a direct impact on rainfall erosivity. Increasing changes in demography have led to the acceleration of land cover changes in natural areas, as well as in cultivated areas, and, sometimes, in degraded areas and desertified landscapes. These anthropogenized landscapes are more sensitive to erosion. On the other hand, the increase in the number of dams in watersheds traps a great portion of sediment fluxes, which do not reach the sea in the same amount, nor at the same quality, with consequences on coastal geomorphodynamics. This book is dedicated to studies on sediment fluxes from continental areas to coastal areas, as well as observation, modeling, and impact analysis at different scales from watershed slopes to the outputs of large river basins. This book is concentrated on a number of keywords: “erosion” and “sediment transport”, “model” and “practice”, and “change”. The keywords are briefly discussed with respect to the relevant literature. The contributions in this book address observations and models based on laboratory and field data, allowing researchers to make use of such resources in practice under changing conditions.
Download or read book Sediment Transport Dynamics written by Weiming Wu and published by CRC Press. This book was released on 2023-11-21 with total page 669 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the fundamentals of sediment transport in surface waters. It covers sediment properties, open channel flows, sediment particle settling, incipient motion, bed forms, bed load, suspended load, total load, cohesive sediments, water-sediment two-phase flows, hyperconcentrated flows, debris flows, wave-induced sediment transport, turbidity currents, and physical modeling. Besides the primary context of river sedimentation, this book extensively covers sediment transport under coexisting waves and currents in coasts and estuaries, hyperconcentrated and debris flows in rivers, as well as turbidity currents in lakes, reservoirs, channels, and the ocean. It includes a chapter on the water-sediment two-phase flow theory, which is considered the basis of many sediment transport models. It introduces some special topics have that emerged in recent years, such as the transport of mixed cohesive and noncohesive sediments, biofilm-coated sediments, and infiltrated sand within gravel and cobble beds. The text merges classical and new knowledge of sediment transport from various sources in English and non-English literature and includes important contributions made by many scientists and engineers from all over the world. It balances the breadth, depth, fundamental importance, practical applicability, and future advancement of the covered knowledge, and can be used as a text and reference book. The chapters are arranged in a useful sequence for teaching purposes. Certain homework problems are prepared, which also highlight the important topics for instructors to select. Solutions to homework problems are available from the author by request.
Download or read book Fluvial Hydrodynamics written by Subhasish Dey and published by Springer. This book was released on 2014-08-22 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt: The state-of-the-art in fluvial hydrodynamics can be examined only through a careful exploration of the theoretical development and applied engineering technology. The book is primarily focused, since most up-to-date research findings in the field are presented, on the research aspects that involve a comprehensive knowledge of sediment dynamics in turbulent flows. It begins with the fundamentals of hydrodynamics and particle motion followed by turbulence characteristics related to sediment motion. Then, the sediment dynamics is analysed from a classical perspective by applying the mean bed shear approach and additionally incorporating a statistical description for the role of turbulence. The work finally examines the local scour problems at hydraulic structures and scale models. It is intended to design as a course textbook in graduate / research level and a guide for the field engineers as well, keeping up with modern technological developments. Therefore, as a simple prerequisite, the background of the readers should have a basic knowledge in hydraulics in undergraduate level and an understanding of fundamentals of calculus.
Download or read book Two phase Modeling of Granular Sediment for Sheet Flows and Scour written by Laurent Olivier Amoudry and published by . This book was released on 2008 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Computational Fluid Dynamics for Emerging Engineering Processes written by Albert S. Kim and published by BoD – Books on Demand. This book was released on 2019-12-11 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: As researchers deal with processes and phenomena that are geometrically complex and phenomenologically coupled the demand for high-performance computational fluid dynamics (CFD) increases continuously. The intrinsic nature of coupled irreversibility requires computational tools that can provide physically meaningful results within a reasonable time. This book collects the state-of-the-art CFD research activities and future R
Download or read book Calculation of Suspended Sediment Transport by Combined Wave current Flows written by Palitha Nalin Wikramanayake and published by . This book was released on 1994 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stochastic Modeling of Suspended Sediment Transport in Regular and Extreme Flow Environments written by and published by . This book was released on 2008 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transport of sediments creates a variety of environmental impacts because it not only induces erosion and deposition problems, but also transfers contaminants or viruses adhered or coupled with the sediments. A better understanding of the fundamental sediment transport processes is significant for environmental researchers to provide practical and scientifically sound solutions to hydraulic engineering problems. Stochastic characteristics of sediment transport have been identified from experiment data. The trajectory of a sediment particle is stochastic due to the probabilistic nature of the flow and sediment conditions. The main goal of the study is to develop a stochastic model governing suspended sediment transport. In this research, several issues related to stochastic modelling of suspended sediment transport are discussed: the numerical scheme for the Fokker-Planck equation; suspended sediment transport in regular surface flows; and suspended sediment transport in extreme flow environments. A fourth-order accurate numerical scheme has been developed for the two-dimensional advection-diffusion (A-D) equation in a staggered-grid system. The first-order spatial derivatives are approximated by the fourth-order accurate finite-difference scheme, thus all truncation errors are kept to a smaller order of magnitude than those of the diffusion terms. For the time derivative, the fourth-order accurate Adams-Bashforth predictor-corrector method is applied. The stability analysis of the proposed scheme is carried out using the Von Neumann method. It is shown that the proposed algorithm has good stability. The proposed numerical scheme can provide more accurate results for long-time simulations validated against analytical and/or numerical solutions. A stochastic partial differential equation based model has been derived based on the law of conservation of mass and the Langevin equation of particle displacement to simulate suspended sediment transport in open-channel flows. The proposed model, explicitly expressing the randomness of sediment concentrations, has the advantage of capturing an instantaneous profile of sediment concentrations including not only the mean but also the variance compared with the deterministic A-D equation. As a result, the probability distribution of the sediment transport rate can be characterized based on a number of realizations obtained in the numerical experiments. The lattice approximation is applied to solve the SPDE of suspended sediment transport in open channel flow. The ensemble mean sediment concentration of the proposed SPDE, obtained by the Monte Carlo simulation, agrees well with that of the deterministic A-D equation. This study proposed a stochastic jump diffusion model in response to extreme flows to describe the movement of sediment particles in surface waters. The proposed approach classifies the movement of particles into three categories - a drift motion, a Brownian type motion due to turbulence in the flow field for example, and jumps due to occurrence of extreme events. In the proposed stochastic diffusion jump model, the occurrence of the extreme flow events is modeled as a Poisson process. The frequency of occurrence of the extreme events in the stochastic diffusion jump model can be explicitly accounted for in the evaluation of movement of sediment particles. The ensemble mean and variance of particle trajectory can be obtained from the proposed model. As such, the stochastic diffusion jump model, when coupled with an appropriate hydrodynamic model, can assist in developing a forecast model to predict the movement of particles in the presence of extreme flows.
Download or read book Modelling and Simulation of Diffusive Processes written by S.K. Basu and published by Springer Science & Business Media. This book was released on 2014-04-15 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book addresses the key issues in the modeling and simulation of diffusive processes from a wide spectrum of different applications across a broad range of disciplines. Features: discusses diffusion and molecular transport in living cells and suspended sediment in open channels; examines the modeling of peristaltic transport of nanofluids, and isotachophoretic separation of ionic samples in microfluidics; reviews thermal characterization of non-homogeneous media and scale-dependent porous dispersion resulting from velocity fluctuations; describes the modeling of nitrogen fate and transport at the sediment-water interface and groundwater flow in unconfined aquifers; investigates two-dimensional solute transport from a varying pulse type point source and futile cycles in metabolic flux modeling; studies contaminant concentration prediction along unsteady groundwater flow and modeling synovial fluid flow in human joints; explores the modeling of soil organic carbon and crop growth simulation.
Download or read book NBS Special Publication written by and published by . This book was released on 1980 with total page 964 pages. Available in PDF, EPUB and Kindle. Book excerpt:
