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CHAPTER 4. HYDRODYNAMIC MODELS
and difficulties and consequently its own “best solution”; and it
is up to the knowledge, experience, and even intuition of the
model designer to see it. (Yalin 1989).
The purpose of this and following chapters is to present some of the “knowledge” that others have gained through experience.
4.1 Introduction to Hydrodynamic Models
Coastal engineers commonly employ two fundamental types of physical
models: Fixed-bed models to study hydrodynamic phenomena in the
coastal regime, and Movable-bed models to study the effects of water
motion on deposition and transport of sediment. This chapter is devoted
to fixed-bed, or Hydrodynamic models1, whereas movable-bed models are
discussed in Chapter 6.
Note that movable-bed models are also hydrodynamic models because they will
also model hydrodynamic process. However, for convenience, the author has elected to
restrict the term hydrodynamic model to fixed-bed models.
Coastal hydrodynamics involves waves and currents in the coastal region. Wave motions can be separated into two logical divisions: short
waves which have wave periods in nature between 1-20 seconds; and long
waves which can have periods ranging between minutes and days (Dalrymple 1985).
The division of waves by period is well suited to modeling (both physical and numerical) because in each case certain terms in the governing
equations are dominant while other terms are less important. This simplifies model scaling requirements to better fit the assumption that dynamic
similarity is achieved by a balance between only two dominant forces.
Short-wave models are used to study wind wave and swell effects on
coastal projects, beaches, and navigation; and long-wave models are used
to study the effects of tides, tsunamis, and other long-period waves on harbors, ports, estuaries, and tidal inlets. Some coastal engineering projects,
such as design of a harbor, must evaluate both short- and long-wave impacts. Short waves can enter the harbor and create a “chop” that makes
small-craft mooring and navigation difficult and dangerous. On the other
hand, long-wave energy can excite the harbor at a basic mode of oscillation
that can cause difficulties for larger moored vessels. Generally, both types
of wave motion cannot be investigated in the same physical model unless
the harbor is quite small.
CHAPTER 4. HYDRODYNAMIC MODELS
and difficulties and consequently its own “best solution”; and it
is up to the knowledge, experience, and even intuition of the
model designer to see it. (Yalin 1989).
The purpose of this and following chapters is to present some of the “knowledge” that others have gained through experience.
4.1 Introduction to Hydrodynamic Models
Coastal engineers commonly employ two fundamental types of physical
models: Fixed-bed models to study hydrodynamic phenomena in the
coastal regime, and Movable-bed models to study the effects of water
motion on deposition and transport of sediment. This chapter is devoted
to fixed-bed, or Hydrodynamic models1, whereas movable-bed models are
discussed in Chapter 6.
Note that movable-bed models are also hydrodynamic models because they will
also model hydrodynamic process. However, for convenience, the author has elected to
restrict the term hydrodynamic model to fixed-bed models.
Coastal hydrodynamics involves waves and currents in the coastal region. Wave motions can be separated into two logical divisions: short
waves which have wave periods in nature between 1-20 seconds; and long
waves which can have periods ranging between minutes and days (Dalrymple 1985).
The division of waves by period is well suited to modeling (both physical and numerical) because in each case certain terms in the governing
equations are dominant while other terms are less important. This simplifies model scaling requirements to better fit the assumption that dynamic
similarity is achieved by a balance between only two dominant forces.
Short-wave models are used to study wind wave and swell effects on
coastal projects, beaches, and navigation; and long-wave models are used
to study the effects of tides, tsunamis, and other long-period waves on harbors, ports, estuaries, and tidal inlets. Some coastal engineering projects,
such as design of a harbor, must evaluate both short- and long-wave impacts. Short waves can enter the harbor and create a “chop” that makes
small-craft mooring and navigation difficult and dangerous. On the other
hand, long-wave energy can excite the harbor at a basic mode of oscillation
that can cause difficulties for larger moored vessels. Generally, both types
of wave motion cannot be investigated in the same physical model unless
the harbor is quite small.