Download or read book Modeling Analysis and Simulation of Two Geophysical Flows Sediment Transport and Variable Density Flows written by Léa Boittin and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present thesis deals with the modeling and numerical simulation of complex geophysical flows. Two processes are studied: sediment transport, and variable density flows. For both flows, the approach is the same. In each case, a reduced vertically-averaged model is derived from the 3D Navier-Stokes equations by making a specific asymptotic analysis. The models verify stability properties. Attention is paid to preserving these properties at the discrete level, in particular the entropy stability. The behavior of both models is illustrated numerically. Concerning the sediment transport model, the sediment layer is first studied alone. Then, a coupled sediment-water model is presented and simulated. The influence of a viscosity term in the model for the sediment layer is investigated. Due to this viscosity term, the sediment flux is non-local. A transport threshold is added to the model. The water layer is modeled by the Shallow Water equations. Adding some non-locality to the model allows to simulate dune growth and propagation. In the variable density flow model, the density is a function of one or several tracers such as temperature and salinity. The model derivation consists in removing the dependence of the density on the pressure. A layer-averaged formulation of the model is proposed, which is subsequently used to propose a numerical discretization. The numerical simulations emphasize the differences between this model and a model relying on the classical Boussinesq approximation.
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 Modeling Density Driven Flow in Porous Media written by Ekkehard O. Holzbecher and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling of flow and transport in groundwater has become an important focus of scientific research in recent years. Most contributions to this subject deal with flow situations, where density and viscosity changes in the fluid are neglected. This restriction may not always be justified. The models presented in the book demonstrate immpressingly that the flow pattern may be completely different when density changes are taken into account. The main applications of the models are: thermal and saline convection, geothermal flow, saltwater intrusion, flow through salt formations etc. This book not only presents basic theory, but the reader can also test his knowledge by applying the included software and can set up own models.
Download or read book Computational River Dynamics written by Weiming Wu and published by CRC Press. This book was released on 2007-11-15 with total page 509 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive text on the fundamentals of modeling flow and sediment transport in rivers treating both physical principles and numerical methods for various degrees of complexity. Includes 1-D, 2-D (both depth- and width-averaged) and 3-D models, as well as the integration and coupling of these models. Contains a broad selection
Download or read book Avalanche Dynamics written by S.P. Pudasaini and published by Springer Science & Business Media. This book was released on 2007-06-30 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt: Avalanches, mudflows and landslides are common and natural phenomena that occur in mountainous regions. With an emphasis on snow avalanches, this book provides a survey and discussion about the motion of avalanche-like flows from initiation to run out. An important aspect of this book is the formulation and investigation of a simple but appropriate continuum mechanical model for the realistic prediction of geophysical flows of granular material.
Download or read book Open channel Flow Through Simulated Vegetation written by Fabian Lopez and published by . This book was released on 1997 with total page 128 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 Efficient Simulation Tools EST for Sediment Laden Shallow Flows written by Sergio Mart√≠nez-Aranda and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid flows of water-sediment mixtures are probably the most challenging and unknown geophysical gravity-driven processes. The fluidized material in motion consists of a mixture of water and multiple solid phases with different specific characteristics. Modeling sediment transport involves an increasing complexity due to the variable bulk properties in the sediment-water mixture, the coupling of physical processes, and the presence of multiple layer phenomena. Two-dimensional shallow-type mathematical models are built in the context of free surface flows and are applicable to most of these geophysical surface processes. Their numerical solution in the finite volume framework is governed by the dynamical properties of the equations, the coupling between flow variables and the computational grid. The complexity of the numerical resolution of these highly unsteady flows and the computational cost of simulation tools increase considerably with the refinement of the non-structured spatial discretization, so that the computational effort required is one of the biggest challenges for the application of depth-averaged 2D models to large-scale long-term flows. Throughout this chapter, the combination of 2D mathematical models, robust numerical methods, and efficient computing kernels is addressed to develop Efficient Simulation Tools (EST,Äôs) for environmental surface processes involving sediment transport with realistic temporal and spatial scales.
Download or read book Computer Modeling of Free Surface and Pressurized Flows written by M. Hanif Chaudhry and published by Springer. This book was released on 1994-07-31 with total page 760 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the NATO Advanced Study Institute, Pullman, WA, U.S.A., June 28--July 9, 1993
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 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 Turbulent Open Channel Flow Sediment Erosion and Sediment Transport written by Clemens Chan-Braun and published by KIT Scientific Publishing. This book was released on 2014-07-30 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis aims to contribute to a better understanding of turbulent open channel flow, sediment erosion and sediment transport. The thesis provides an analysis of high-fidelity data from direct numerical simulation of (i) open channel flow over an array of fixed spheres, (ii) open channel flow with mobile eroding spheres, (iii) open channel flow with sediment transport of many mobile spheres. An immersed boundary method is used to resolve the finite-size particles.
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 Sediment Transport and Morphodynamics Modelling for Coasts and Shallow Environments written by Vanesa Magar and published by CRC Press. This book was released on 2020-03-09 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: This reference for engineers, and graduate students covers sediment transport and morphodynamics modelling in nearshore environments. It presents the fundamentals required for understanding the physics and for setting up numerical models. This book covers hydrodynamics of estuarine and coastal environments, properties of seafloor and estuarine composition, and hydroenvironmental interactions; emphasising the inter-relations of small- and large-scale processes, and short- and large-evolution timescales. The focus is, principally, on the application of shallow-water theory, but some surface wave models, and coupling of shallow-water models with surface waves is also discussed to some extent. The guidance on running regional models and the case studies presented are directed to managed realignment, coastal protection, climate change impacts, and offshore renewables. Key features: Gives a balanced review of this rich interdisciplinary area Bridges practical engineering and research Offers both large- and small-scale application Suits graduate students and researchers as well as consulting engineers Vanesa Magar is a senior researcher and associate professor at the Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE) in Baja California, Mexico. She was formerly a researcher and then a lecturer at Plymouth University, UK.
Download or read book Modelling and Analysis of Fine Sediment Transport in Wave Current Bottom Boundary Layer written by Liqin Zuo and published by CRC Press. This book was released on 2018-06-19 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: The evolution and utilization of estuarine and coastal regions are greatly restricted by sediment problems. This thesis aims to better understand fine sediment transport under combined action of waves and currents, especially in the wave-current bottom boundary layer (BBL). Field observations, experimental data analysis, theoretical analysis and numerical models are employed. Silt-dominated sediments are sensitive to flow dynamics and the suspended sediment concentration (SSC) increase rapidly under strong flow dynamics. This research unveils several fundamental aspects of silty sediment, i.e., the criterion of the incipient motion, the SSC profiles and their phase-averaged parameterization in wave-dominated conditions. An expression for sediment incipient motion is proposed for silt-sand sediment under combined wave and current conditions. A process based intra-wave 1DV model for flow-sediment dynamics near the bed is developed in combined wave-current conditions. The high concentration layer (HCL) was simulated and sensitivity analysis was carried out by the 1DV model on factors that impact the SSC in the HCL. Finally, based on the 1DV model, the formulations of the mean SSC profile of silt-sand sediments in wave conditions were proposed. The developed approaches are expected to be applied in engineering practice and further simulation.
Download or read book Simulation of Surface Water Integrated Flow and Transport in Two Dimensions written by Raymond W. Schaffranek and published by CreateSpace. This book was released on 2014-06-23 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical model for simulation of surface-water integrated flow and transport in two (horizontal-space) dimensions is documented. The model solves vertically integrated forms of the equations of mass and momentum conservation and solute transport equations for heat, salt, and constituent fluxes. An equation of state for salt balance directly couples solution of the hydrodynamic and transport equations to account for the horizontal density gradient effects of salt concentrations on flow.
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:
