Jørgen Fredsøe

Bio: Jørgen Fredsøe is an academic researcher from Technical University of Denmark. The author has contributed to research in topics: Sediment transport & Turbulence. The author has an hindex of 57, co-authored 223 publications receiving 13672 citations. Previous affiliations of Jørgen Fredsøe include DHI Water & Environment & Indian Institute of Technology Kharagpur.

Mechanics Of Coastal Sediment Transport

Abstract: The main objective of the book is to describe from a deterministic point of view the sediment transport in the general wave-current situation. For this purpose, the book is divided into two major parts. The first part of the book is related to flow and turbulence in combined wave-current. This part covers the turbulent wave boundary layer, bed friction in combined wave-current motion, turbulence in the surf zone, and wave-driven currents in the long- and cross-shore direction. The second part treats the sediment transport as a result of the wave-current action. This part includes an introduction to basic sediment transport concepts, distribution of suspended sediment in the sheet flow regime, description of bedforms formed by current and waves, and their influence on sediment transport pattern. Finally, the modelling of cross- and long-shore sediment transport is described. This book is useful for students with a background in basic hydrodynamics.

Hydrodynamics around cylindrical structures

Abstract: This work discusses the subject of wave/current flow around a cylinder, the forces induced on the cylinder by the flow and the vibration pattern of slender structures in a marine environment. The primary aim of the book is to describe the flow pattern and the resulting load which develops when waves or current meet a cylinder. Attention is paid to the special case of a circular cylinder. The development in the forces is related to the various flow patterns and is discussed in detail. Regular as well as irregular waves are considered, and special cases like wall proximities (pipelines) are also investigated. The book is intended for MSc students with some experience in basic fluid mechanics and for PhD students.

A wave generation toolbox for the open‐source CFD library: OpenFoam®

Abstract: SUMMARY The open-source CFD library OpenFoam® contains a method for solving free surface Newtonian flows using the Reynolds averaged Navier–Stokes equations coupled with a volume of fluid method. In this paper, it is demonstrated how this has been extended with a generic wave generation and absorption method termed ‘wave relaxation zones’, on which a detailed account is given. The ability to use OpenFoam for the modelling of waves is demonstrated using two benchmark test cases, which show the ability to model wave propagation and wave breaking. Furthermore, the reflection coefficient from outlet relaxation zones is considered for a range of parameters. The toolbox is implemented in C++, and the flexibility in deriving new relaxation methods and implementing new wave theories along with other shapes of the relaxation zone is outlined. Subsequent to the publication of this paper, the toolbox has been made freely available through the OpenFoam-Extend Community. Copyright © 2011 John Wiley & Sons, Ltd.

The mechanics of scour in the marine environment

Abstract: Scour Below Pipelines Scour Around a Single Slender Pile Scour Around a Group of Slender Piles Examples of More Complex Configurations Scour Around Large Piles Scour Around Breakwaters Scour at Seawalls Ship-Propeller Scour Impact of Liquefaction.

A Sediment Transport Model for Straight Alluvial Channels

Abstract: The paper presents a simple mathematical model for sediment transport in straight alluvial channels. The model, which is based on physical ideas related to those introduced by Bagnold (1954), was originally developed in two steps, the first describing the bed load transport (Engelund 1975) and the second accounting for the suspended load (Fredsoe and Engelund 1976). The model is assumed to have two advantages as compared with empirical models, first it is based on a description of physical processes, secondly it gives some information about the quantity and size of the sand particles in suspension and the bed particles.

Boundary Layer Theory

Abstract: The boundary layer equations for plane, incompressible, and steady flow are $$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Sediment transport; Part I, Bed load transport

Abstract: A method is presented which enables the computation of the bed-load transport as the product of the saltation height, the particle velocity and the bed-load concentration. The equations of motions for a solitary particle are solved numerically to determine the saltation height and particle velocity. Experiments with gravel particles (transported as bed load) are selected to calibrate the mathematical model using the lift coefficient as a free parameter. The model is used to compute the saltation heights and lengths for a range of flow conditions. The computational results are used to determine simple relationships for the saltation characteristics. Measured transport rates of the bed load are used to compute the sediment concentration in the bed-load layer. A simple expression specifying the bed-load concentration as a function of the flow and sediment conditions is proposed. A verification analysis using about 600 (alternative) data shows that about 77% of the predicted bed-load-transport rates are within 0.5 and 2 times the observed values.

Sediment Transport, Part II: Suspended Load Transport

Abstract: A method is presented which enables the computation of the suspended load as the depth-integration of the product of the local concentration and flow velocity. The method is based on the computation of the reference concentration from the bed-load transport. Measured concentration profiles have been used for calibration. New relationships are proposed to represent the size gradation of the bed material and the damping of the turbulence by the sediment particles. A verification analysis using about 800 data shows that about 76% of the predicted values are within 0.5 and 2 times the measured values.