1.5. OVERVIEW OF HYDRAULIC PHYSICAL MODELS
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c. Obtain measurements for phenomena so complicated that so
far they have not been accessible for theoretical approaches
(e.g., stability of rubble-mound breakwaters, or sediment
suspension over a rippled bed).
Dalrymple (1989) broadly classified physical models into what could be
considered two “goal-related” categories. The first type are those physical
models used to verify (or extend) numerical models. These models may
not resemble anything in the real world because often they are idealized
and simplified to minimize scale effects and to provide a test case that
more closely fits the assumptions inherent in the numerical model. Physical models of this type could be referred to as validation models. The
rationale for simplified “validation” physical models is that
.. .if we can not predict [with the numerical model] the behavior
of a simple laboratory test case, with its restricted number of
variables, then we certainly can not expect to predict the behavior of the real world prototype. (Dalrymple 1989).
An example of a validation model would be an idealized, rectangular harbor
constructed with perfectly reflecting vertical side walls.
The second type of physical model has the goal of attempting to predict prototype behavior by reproducing to the extent possible all the features and forces of an actual prototype situation. Kamphuis (1991) terms
this type of physical model a design model. Design physical models are
intended to provide an engineering solution to a problem (or problems),
and they are far more difficult to conduct because of scaling problems, unknowns, and the expense in gathering sufficient prototype data to construct
the model and then verify correct model response. Some design models do
not represent a specific project site, but are instead used generically to
develop design guidance. Example design models include models of harbor response to short and long waves, models of breakwater stability, and
models of ship mooring loads.
Kamphuis (1991) provided a third type of “goal-related” model he referred to as the process model. This is a physical model designed to
study a physical process in detail in order to develop new understanding
about the physics. Process models correspond to the traditional “laboratory experiment.” Examples of process physical models include studies of
sediment transport rates, examination of flow forces around cylinders, or
shoaling of nonlinear waves.
Kamphuis (1991) stated that the future of physical modeling will be
directly toward the “process model” because they are unique research tools
11
c. Obtain measurements for phenomena so complicated that so
far they have not been accessible for theoretical approaches
(e.g., stability of rubble-mound breakwaters, or sediment
suspension over a rippled bed).
Dalrymple (1989) broadly classified physical models into what could be
considered two “goal-related” categories. The first type are those physical
models used to verify (or extend) numerical models. These models may
not resemble anything in the real world because often they are idealized
and simplified to minimize scale effects and to provide a test case that
more closely fits the assumptions inherent in the numerical model. Physical models of this type could be referred to as validation models. The
rationale for simplified “validation” physical models is that
.. .if we can not predict [with the numerical model] the behavior
of a simple laboratory test case, with its restricted number of
variables, then we certainly can not expect to predict the behavior of the real world prototype. (Dalrymple 1989).
An example of a validation model would be an idealized, rectangular harbor
constructed with perfectly reflecting vertical side walls.
The second type of physical model has the goal of attempting to predict prototype behavior by reproducing to the extent possible all the features and forces of an actual prototype situation. Kamphuis (1991) terms
this type of physical model a design model. Design physical models are
intended to provide an engineering solution to a problem (or problems),
and they are far more difficult to conduct because of scaling problems, unknowns, and the expense in gathering sufficient prototype data to construct
the model and then verify correct model response. Some design models do
not represent a specific project site, but are instead used generically to
develop design guidance. Example design models include models of harbor response to short and long waves, models of breakwater stability, and
models of ship mooring loads.
Kamphuis (1991) provided a third type of “goal-related” model he referred to as the process model. This is a physical model designed to
study a physical process in detail in order to develop new understanding
about the physics. Process models correspond to the traditional “laboratory experiment.” Examples of process physical models include studies of
sediment transport rates, examination of flow forces around cylinders, or
shoaling of nonlinear waves.
Kamphuis (1991) stated that the future of physical modeling will be
directly toward the “process model” because they are unique research tools