162
CHAPTER 4. HYDRODYNAMIC MODELS
4.4 Other Model Study Considerations
Many engineering applications have associated with them aspects that are
unique to individual situations, and good engineering involves being able
to recognize that part of the problem not covered in the textbooks and
manuals. This is certainly true for hydrodynamic modeling, whether it be
physical or numerical modeling of a coastal flow situation.
Before designing any physical model, the hydrodynamic regime must be
analyzed in enough detail to establish the proper extent of model boundaries
and to determine representative environmental test conditions. These test
conditions and model forcing inputs can consist of some combination of
• Short- and long-wave heights and periods and incident
wave directions.
• Spectral shapes (and directional spreading) for irregular
wave forcing.
• Water level elevations associated with different phases of
the tide, storm surge, or tsunamis. (Higher water levels
permit more wave energy to enter the harbor or to runup
on a beach or structure.)
• Currents resulting from tidal exchange, longshore currents,
or other physical mechanism.
• River flow input rates.
• Any other hydrodynamic forcing that is considered significant for the particular problem being modeled.
Often prototype wave measurements or wave hindcasts are used in selecting the representative wave conditions, and these wave conditions must
be analytically or numerically transformed from the water depth associated
with the data to a water depth represented by the depth adjacent to the
model wave generator.
Prototype data requirements will vary with the type of study being
performed, but typical needs are wave data, current measurements, historic water level information, and detailed bathymetric data. If existing
structures are to be modeled, it is necessary to obtain design details and
dimensions so they can be reproduced in the model.
Decisions on where data are collected in a physical model are largely
dictated by what processes are being investigated with the model. Typically, wave data are collected in deeper water near the wave machine, and
at locations within the modeled regime where wave height may be a critical
design factor. For example, in a long-wave harbor model, design criteria
CHAPTER 4. HYDRODYNAMIC MODELS
4.4 Other Model Study Considerations
Many engineering applications have associated with them aspects that are
unique to individual situations, and good engineering involves being able
to recognize that part of the problem not covered in the textbooks and
manuals. This is certainly true for hydrodynamic modeling, whether it be
physical or numerical modeling of a coastal flow situation.
Before designing any physical model, the hydrodynamic regime must be
analyzed in enough detail to establish the proper extent of model boundaries
and to determine representative environmental test conditions. These test
conditions and model forcing inputs can consist of some combination of
• Short- and long-wave heights and periods and incident
wave directions.
• Spectral shapes (and directional spreading) for irregular
wave forcing.
• Water level elevations associated with different phases of
the tide, storm surge, or tsunamis. (Higher water levels
permit more wave energy to enter the harbor or to runup
on a beach or structure.)
• Currents resulting from tidal exchange, longshore currents,
or other physical mechanism.
• River flow input rates.
• Any other hydrodynamic forcing that is considered significant for the particular problem being modeled.
Often prototype wave measurements or wave hindcasts are used in selecting the representative wave conditions, and these wave conditions must
be analytically or numerically transformed from the water depth associated
with the data to a water depth represented by the depth adjacent to the
model wave generator.
Prototype data requirements will vary with the type of study being
performed, but typical needs are wave data, current measurements, historic water level information, and detailed bathymetric data. If existing
structures are to be modeled, it is necessary to obtain design details and
dimensions so they can be reproduced in the model.
Decisions on where data are collected in a physical model are largely
dictated by what processes are being investigated with the model. Typically, wave data are collected in deeper water near the wave machine, and
at locations within the modeled regime where wave height may be a critical
design factor. For example, in a long-wave harbor model, design criteria