This book investigates the formation of subaqueous patterns by means of high-fidelity numerical simulations which resolve all the relevant scales of the flow and the sediment bed. This is required to provide a space- and time-resolved information on the flow field and the sediment bed. Secondly, detailed analysis of the generated data allows to address the different governing mechanisms involved in the formation of patterns as well as to access the validity of various existing models. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.

This book investigates the formation of subaqueous patterns by means of high-fidelity numerical simulations which resolve all the relevant scales of the flow and the sediment bed. This is required to provide a space- and time-resolved information on the flow field and the sediment bed. Secondly, detailed analysis of the generated data allows to address the different governing mechanisms involved in the formation of patterns as well as to access the validity of various existing models.

The origin of secondary currents and subaqueous sediment patterns in natural rivers is analysed from first principles. For this purpose, simulations of sediment transport in canonical turbulent open channel flows are performed using a numerical technique that resolves all relevant flow scales and the dynamics of the individual sand grains. The high-fidelity datasets reveal the fundamental importance of individual coherent structures for the development of sediment patterns and secondary flows.

Modelling Approaches and Computational Methods for Particle-laden Turbulent Flows introduces the principal phenomena observed in applications where turbulence in particle-laden flow is encountered while also analyzing the main methods for analyzing numerically. The book takes a practical approach, providing advice on how to select and apply the correct model or tool by drawing on the latest research. Sections provide scales of particle-laden turbulence and the principal analytical frameworks and computational approaches used to simulate particles in turbulent flow. Each chapter opens with a section on fundamental concepts and theory before describing the applications of the modelling approach or numerical method. Featuring explanations of key concepts, definitions, and fundamental physics and equations, as well as recent research advances and detailed simulation methods, this book is the ideal starting point for students new to this subject, as well as an essential reference for experienced researchers. - Provides a comprehensive introduction to the phenomena of particle laden turbulent flow - Explains a wide range of numerical methods, including Eulerian-Eulerian, Eulerian-Lagrange, and volume-filtered computation - Describes a wide range of innovative applications of these models

The transport of bacteria in turbulent river-like environments is addressed, where bacterial populations are frequently encountered attached to solids. This transport mode is investigated by studying the transient settling of heavy particles in turbulent channel flows featuring sediment beds. A numerical method is used to fully resolve turbulence and finite-size particles, which enables the assessment of the complex interplay between flow structures, suspended solids and river sediment.

Analysis of sediment cores from an area of the eastern Central Pacific basin revealed varied characteristics of the cores and associated acoustical properties of the sediments that enabled the study area to be divided into five provinces. Two of the provinces, one consisting of acoustically highly transparent siliceous ooze and the other of highly stratified calcareous ooze, are separated by a third, a siliceous-calcareous transition zone. A fourth province consists of partially eroded, highly stratified sediments of Tertiary age which are unconformably overlain by a thin, transparent siliceous ooze of Quaternary age. The fifth province consists of channels arranged in a distributary-like pattern that contain highly stratified sediments incised into surrounding transparent siliceous sediments. Surface sediment distribution was generally consistent with the calcite compensation depth of about 5000 meters.

This monograph presents the mechanistic foundations of the theory of Morhodynamics, a discipline that investigates the shape of the erodible boundary of natural water bodies. We focus on the fluvial Morphodynamics of straight erodible channels, providing the basis for subsequent extensions to meandering rivers (treated in the companion monograph 2 of this series) and braided rivers. We present basic notions on the Mechanics of Turbulent Flows and Sediment Transport in straight open channels with mobile beds. We then investigate their morphodynamic equilibrium and its instability, that leads to the formation of a variety of bedforms observed in natural rivers. In particular, fluvial bars will deserve special attention as the fundamental building block of large scale fluvial patterns.