Physical modelling in coastal engineering

Proceedings of an international conference, Newark, Delaware, August 1981

R.A. Dalrymple

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9789061915164
• eBook ISBN: 9781351424639
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

Coastal engineering is a field which has grown in importance over the last forty years as mankind has utilised and become dependent on the coastlines of the world to a greater extent. The activities in the field include the study of wave dynamics, shoreline erosion and protection, harbor and breakwater design, dredging technology, estuary mechanics and storm surge calculations, as well as offshore structural design. In all of these areas the level of actvity is high and the state of art has imporved dramatically since the 1940's. An important aspect of all these areas of research is the use of model studies. This volume consists of a number of papers which cover various aspects of physical modelling in coastal engineering, including the generation of waves in the laboratory, the modelling of sediment transport and the application to various engineering problems. The intent is to provide the reader with an overview of the research actvities of indviduals who represent major laboratories in their countries: to include Denmark, Scotland, Canada, the People's Republic of China, England, the Netherlands and the U.S.

1. Introduction to physical modelling

Introduction to physical models in coastal engineering

ROBERT A. DALRYMPLE

Department of Civil Engineering & College of Marine Studies, University of Delaware, Newark, USA

Introduction

Physical models provide the engineer and scientist two significant advantages when studying a particular coastal engineering problem. The first is that nature is used to integrate the appropriate equations which govern the phenomena, whether it be wave propagation into harbors or sand transport on a beach. No simplifying assumptions are used and no unknowns are omitted, as often occurs in analytical or numerical modelling. The second advantage is that the size of the model is much smaller than the prototype, permitting the easier acquisition of relevant data.

There are, of course, drawbacks, such as the introduction of scale effects, which are due to changes in the relative importance of various forces (such as surface tension) as the model becomes smaller than the prototype. Additionally, the model is generally more simplistic than the prototype, for example, the use of monochromatic (single frequency) waves to study real sea states or, since the advent of spectral wave generators, using ‘real’ sea states, but neglecting wind and other potentially important forces in nature.

The purpose of this introduction is to provide a brief overview of the modelling laws which permit the experimenter to scale the model results up to the prototype size.

In coastal engineering, there are two types of models commonly used, fixed bed models (to study, for example, wave propagation and currents) and movable bed models (to study the deposition and transport of sediment). The modelling criteria for each are different and will be treated separately here.

1. Wave Propagation Models

These models are of two kinds: Short wave models (wave periods of, say, 1−20 seconds) which are used to study waves impinging on offshore and coastal structures, or long wave models (wave periods of the order of minutes up to days) for the study of tsunami effects and tidal propagation through inlets and in estuaries. These types of models are usually conducted with an immovable bottom and are referred to as fixed bed models.

The criteria for a model to replicate the prototype involves several types of similarity. Geometric similarity requires that the model and the prototype look the same....

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Contents
• Foreword
• 1. Introduction to Physical Modelling
• 2. Water Waves in the Laboratory
• 3. Sediment Transport Modelling
• 4. Applications of Modelling
• Participants of the Conference