2
CHAPTER 1. INTRODUCTION
system. Numerical models are mathematical models in which the governing
equations are discretized and solved using a computer.
Measurements and observations of hydrodynamic phenomena made at
a specific site are often critical for understanding the hydrodynamic regime
and its impact on existing or planned coastal projects. These measurements
can be used to quantify the hydraulic flows, to specify hydrodynamics forcing conditions for numerical or physical model studies, or to verify the
correct formulation and operation of numerical or physical model simulations.
Dalrymple (1985) pointed out that field studies provide the best data,
but they are usually expensive and too many of nature’s variables are
present, making data interpretation difficult. In contrast, physical models are smaller, less expensive, easily studied, and simpler than nature, yet
they include most important aspects of the problem. In addition, physical
and numerical model input conditions can be controlled and systematically
varied, whereas field studies have no such control (Kamphuis 1991).
Numerical modeling, a recent newcomer to the list of engineering tools,
has shown steady growth and utility over the past decade. This has been
fueled by the advent of large, fast computers that are readily available and
economic to use. Large physical models of tidal estuary systems have now
been almost totally replaced with numerical models that can predict flows
with a good degree of success. Numerical models are also practical for cases
where wave refraction, shoaling, and diffraction are the only important hydrodynamic characteristics, and considerable success has been shown in
accurately simulating nearshore circulation with numerical models (Kamphuis 1991).
However, many flow conditions and problems in coastal engineering are
not amenable to mathematical analysis because of the nonlinear character
of the governing equations of motion, lack of information on wave breaking, turbulence or bottom friction, or numerous connected water channels
(Keulegan 1966). In these cases it is often necessary to resort to physical
models for predicting prototype behavior or observing results not readily
examined in nature.
The growing use of numerical models in coastal engineering has not
made physical models obsolete. They keep pace with mathematical models
and in some cases make progress in conjunction with them (Martins 1989).
Recent trends have included the concept of “hybrid modeling” where results
from a physical model of a complex region are used as input or boundary
conditions for a comprehensive numerical model covering a wider region of
interest. Alternately, numerical model results may be used to provide input
conditions at the boundaries of the physical model.
Kamphuis (1991) pointed out that physical models will be needed to
CHAPTER 1. INTRODUCTION
system. Numerical models are mathematical models in which the governing
equations are discretized and solved using a computer.
Measurements and observations of hydrodynamic phenomena made at
a specific site are often critical for understanding the hydrodynamic regime
and its impact on existing or planned coastal projects. These measurements
can be used to quantify the hydraulic flows, to specify hydrodynamics forcing conditions for numerical or physical model studies, or to verify the
correct formulation and operation of numerical or physical model simulations.
Dalrymple (1985) pointed out that field studies provide the best data,
but they are usually expensive and too many of nature’s variables are
present, making data interpretation difficult. In contrast, physical models are smaller, less expensive, easily studied, and simpler than nature, yet
they include most important aspects of the problem. In addition, physical
and numerical model input conditions can be controlled and systematically
varied, whereas field studies have no such control (Kamphuis 1991).
Numerical modeling, a recent newcomer to the list of engineering tools,
has shown steady growth and utility over the past decade. This has been
fueled by the advent of large, fast computers that are readily available and
economic to use. Large physical models of tidal estuary systems have now
been almost totally replaced with numerical models that can predict flows
with a good degree of success. Numerical models are also practical for cases
where wave refraction, shoaling, and diffraction are the only important hydrodynamic characteristics, and considerable success has been shown in
accurately simulating nearshore circulation with numerical models (Kamphuis 1991).
However, many flow conditions and problems in coastal engineering are
not amenable to mathematical analysis because of the nonlinear character
of the governing equations of motion, lack of information on wave breaking, turbulence or bottom friction, or numerous connected water channels
(Keulegan 1966). In these cases it is often necessary to resort to physical
models for predicting prototype behavior or observing results not readily
examined in nature.
The growing use of numerical models in coastal engineering has not
made physical models obsolete. They keep pace with mathematical models
and in some cases make progress in conjunction with them (Martins 1989).
Recent trends have included the concept of “hybrid modeling” where results
from a physical model of a complex region are used as input or boundary
conditions for a comprehensive numerical model covering a wider region of
interest. Alternately, numerical model results may be used to provide input
conditions at the boundaries of the physical model.
Kamphuis (1991) pointed out that physical models will be needed to