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 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 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 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 Modeling of Fluid Solid Two Phase Geophysical Flows written by Zhenhua Huang and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid-solid two-phase flows are frequently encountered in geophysical flow problems such as sediment transport and submarine landslides. It is still a challenge to the current experiment techniques to provide information such as detailed flow and pressure fields of each phase, which however is easily obtainable through numerical simulations using fluid-solid two-phase flow models. This chapter focuses on the Eulerian-Eulerian approach to two-phase geophysical flows. Brief derivations of the governing equations and some closure models are provided, and the numerical implementation in the finite-volume framework of OpenFOAM® is described. Two applications in sediment transport and submarine landslides are also included at the end of the chapter.

Download or read book Three dimensional Numerical Analysis of Flow Structure and Sediment Transport Process in Open Channels written by Esteban Sánchez Cordero and published by . This book was released on 2019 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research project focuses on the analysis and prediction of flow structures and sediment transport process in open channels by using three-dimensional numerical models. The numerical study was performed using the open source computational fluid dynamics (CFD) solver based on the finite volume method (FVM) – OpenFOAM. Turbulence is treated by means of the two main methodologies; i.e. Large Eddy Simulation (LES) and Reynolds-Averaged Navier–Stokes (RANS). The free surface is tracked using the Volume of Fluid method (VOF). In addition, a new multi-dimensional model for sediment transport based on the Eulerian two-phase mathematical formulation is applied. The results obtained from the different numerical configurations are verified and validated against experimental data sets published in important research journals. The main characteristics of the flow structures are studied by using three set-up cases in steady and unsteady-state (transient) hydraulic flow conditions. On the other hand, the new multi-dimensional model for sediment transport is applied to predict the local scour caused by submerged wall jet test-case. Non-uniform structured elements are used in the grid configuration of the computational domains. A mesh sensitivity analysis is performed in each test-case study in order to obtain independent grid results. This analysis provides a balance between accuracy and optimal computational time. The results demonstrate that the three-dimensional numerical configurations satisfactorily reproduce the temporal variation of the different variables under study with correct trends and high correlation with the experimental values. Regarding the analysis and prediction of the flow structures, the results show the importance of the turbulence approach in the numerical configuration. On the other hand, the results of the new multi-dimensional two-phase model allow to analyze the full dynamics for sediment transport (concentration profile). Although the numerical results are satisfactory, the application of three-dimensional numerical models in field-scale cases requires a high computational resource.

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 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 Two dimensional Flow Modeling written by Robert C. MacArthur and published by . This book was released on 1982 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multi dimensional Modeling of Sediment Transport written by William H. McAnally and published by . This book was released on 1983 with total page 5 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 Treatise on Geomorphology written by and published by Academic Press. This book was released on 2013-02-27 with total page 6392 pages. Available in PDF, EPUB and Kindle. Book excerpt: The changing focus and approach of geomorphic research suggests that the time is opportune for a summary of the state of discipline. The number of peer-reviewed papers published in geomorphic journals has grown steadily for more than two decades and, more importantly, the diversity of authors with respect to geographic location and disciplinary background (geography, geology, ecology, civil engineering, computer science, geographic information science, and others) has expanded dramatically. As more good minds are drawn to geomorphology, and the breadth of the peer-reviewed literature grows, an effective summary of contemporary geomorphic knowledge becomes increasingly difficult. The fourteen volumes of this Treatise on Geomorphology will provide an important reference for users from undergraduate students looking for term paper topics, to graduate students starting a literature review for their thesis work, and professionals seeking a concise summary of a particular topic. Information on the historical development of diverse topics within geomorphology provides context for ongoing research; discussion of research strategies, equipment, and field methods, laboratory experiments, and numerical simulations reflect the multiple approaches to understanding Earth’s surfaces; and summaries of outstanding research questions highlight future challenges and suggest productive new avenues for research. Our future ability to adapt to geomorphic changes in the critical zone very much hinges upon how well landform scientists comprehend the dynamics of Earth’s diverse surfaces. This Treatise on Geomorphology provides a useful synthesis of the state of the discipline, as well as highlighting productive research directions, that Educators and students/researchers will find useful. Geomorphology has advanced greatly in the last 10 years to become a very interdisciplinary field. Undergraduate students looking for term paper topics, to graduate students starting a literature review for their thesis work, and professionals seeking a concise summary of a particular topic will find the answers they need in this broad reference work which has been designed and written to accommodate their diverse backgrounds and levels of understanding Editor-in-Chief, Prof. J. F. Shroder of the University of Nebraska at Omaha, is past president of the QG&G section of the Geological Society of America and present Trustee of the GSA Foundation, while being well respected in the geomorphology research community and having won numerous awards in the field. A host of noted international geomorphologists have contributed state-of-the-art chapters to the work. Readers can be guaranteed that every chapter in this extensive work has been critically reviewed for consistency and accuracy by the World expert Volume Editors and by the Editor-in-Chief himself No other reference work exists in the area of Geomorphology that offers the breadth and depth of information contained in this 14-volume masterpiece. From the foundations and history of geomorphology through to geomorphological innovations and computer modelling, and the past and future states of landform science, no "stone" has been left unturned!

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 Two dimensional Modeling of Flow Field and Non equilibrium Sediment Transport Over Irregular Domains and Topographies written by Jean-Fernand Krou and published by . This book was released on 2010 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Application of a Two dimensional Sediment Transport Model in a Cumberland Plateau Mountainous Stream Reach with Complex Morphology and Coarse Substrate written by and published by . This book was released on 2008 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among river engineers there is growing recognition that the success of a stream restoration project is dependent on the accurate prediction of sediment transport along a reach. To aid the design process, several numerical one- and multi-dimensional models have been developed to quantify in-stream sediment transport and hydraulic characteristics, and multiple sampling techniques have been proposed to establish the upstream sediment supply. However, the governing physical boundaries and variables (i.e., Manning's 'n' variable, energy slope, and upstream sediment supply) required to initiate a sediment transport simulation are time consuming and difficult to measure in the field, and the estimation of these variables based on best professional judgment can lead to inaccurate predictions of sediment transport, resulting in the design of unstable projects. Thus, there exists a demand to understand the model sensitivity to key input parameters (i.e., Manning's n value and sediment rating curves), and their effects on sediment transport simulations, especially when input parameters must be estimated and results can not be verified easily. The goal of this study was to evaluate the performance of CCHE2D, a two-dimensional sediment transport model, in a Cumberland Plateau mountainous stream reach with complex morphology and coarse substrate. The model was utilized to simulate sediment transport through a single hydrograph. Bed elevation change along a reach (100-m scale), was evaluated by comparing the deviation between simulated and measured elevations at multiple monitoring points before and after the simulated flood event. The study objective included testing the sensitivity of overall bed change at a reach, local, and point scales to two key model inputs parameters, the Manning's n value and sediment supply. Despite the relative stability observed along the site, simulated results show the model overestimated aggradation at a reach, local, and point scales. Statistical analysis of simulated results showed that bed elevation change was most sensitive to the bedload rating curve and Manning's n value input parameters. Importantly, the site-specific bedload rating curve and measured roughness coefficient have the potential to reduce the error between simulated and measured results if accurate simulations of sediment transport can be achieved by a computational model.

Download or read book Multidimensional Effects in Two phase Flow Including Phase Change written by Necdet Kurul and published by . This book was released on 1990 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Environmental Fluid Dynamics Volume Two written by Harindra Joseph Fernando and published by CRC Press. This book was released on 2012-12-12 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt: With major implications for applied physics, engineering, and the natural and social sciences, the rapidly growing area of environmental fluid dynamics focuses on the interactions of human activities, environment, and fluid motion. A landmark for the field, the two-volume Handbook of Environmental Fluid Dynamics presents the basic principles, fundamental flow processes, modeling techniques, and measurement methods used in the study of environmental motions. It also offers critical discussions of environmental sustainability related to engineering. The handbook features 81 chapters written by 135 renowned researchers from around the world. Covering environmental, policy, biological, and chemical aspects, it tackles important cross-disciplinary topics such as sustainability, ecology, pollution, micrometeorology, and limnology. Volume Two: Systems, Pollution, Modeling, and Measurements explores the interactions between engineered structures and anthropogenic activities that affect natural flows, with particular emphasis on environmental pollution. The book covers the numerical methodologies that underpin research, predictive modeling, and cyber-infrastructure developments. It also addresses practical aspects of laboratory experiments and field observations that validate quantitative predictions and help identify new phenomena and processes. As communities face existential challenges posed by climate change, rapid urbanization, and scarcity of water and energy, the study of environmental fluid dynamics becomes increasingly relevant. This volume is a valuable resource for students, researchers, and policymakers working to better understand environmental motions and how they affect and are influenced by anthropogenic activities. See also Handbook of Environmental Fluid Dynamics, Two-Volume Set and Volume One: Overview and Fundamentals.