190
CHAPTER 5. COASTAL STRUCTURE MODELS
• Most air entrainment occurs above the still-water level.
• Air bubbles are entrained in the structure during wave
runup, and then rise vertically due to buoyancy.
• Aeration increases with increasing wave period for a constant wave height.
• Depth of bubble penetration increases with increasing wave
height for a constant wave period.
• Plunging breakers induce the highest degree of aeration.
• Air bubbles due to flow separation moved up slope in the
direction of the wave runup.
• Air concentration and bubble penetration increases with
steeper structure slopes.
• Aeration is more severe in highly permeable structures.
5.2.3
Rubble-Mound Model Verification
Verification of rubble-mound structure model studies is seldom possible.
Most studies involve the testing and optimization of a design that has yet
to be built, and studies of modifications to existing structures rarely have
the necessary prototype data for proper validation. Most model tests rely
on the scaling guidance that has been proven correct by several studies in
which prototype damage has been re-created in a scale model.
Two important aspects of model verification are to assure that waves
and currents produced in the physical model are correctly scaled replicas of
the intended prototype hydrodynamic conditions and the bathymetry is a
reasonable approximation of the prototype. This will help insure the model
is producing the correct response. Just as important is a faithful attempt
to construct the model structure reasonably similar to what exists (or will
exist) in the prototype.
The reliability of rubble-mound stability tests was discussed by Hudson and Davidson (1975) and by T0rum, et al. (1979), and both papers
discussed cases of successful model reproduction of damage that occurred
to actual prototype structures. Hudson and Davidson (1975) compared
damage that occurred to the San Pedro Bay breakwater in 1939 to damage
obtained in a physical model conducted in 1947. Although exact prototype
wave climate was unknown, a reasonable estimate was made for the model,
and prototype-to-model similarity in breakwater cross-section damage led
Hudson and Davidson to conclude that the model was behaving similarly
to the prototype.
CHAPTER 5. COASTAL STRUCTURE MODELS
• Most air entrainment occurs above the still-water level.
• Air bubbles are entrained in the structure during wave
runup, and then rise vertically due to buoyancy.
• Aeration increases with increasing wave period for a constant wave height.
• Depth of bubble penetration increases with increasing wave
height for a constant wave period.
• Plunging breakers induce the highest degree of aeration.
• Air bubbles due to flow separation moved up slope in the
direction of the wave runup.
• Air concentration and bubble penetration increases with
steeper structure slopes.
• Aeration is more severe in highly permeable structures.
5.2.3
Rubble-Mound Model Verification
Verification of rubble-mound structure model studies is seldom possible.
Most studies involve the testing and optimization of a design that has yet
to be built, and studies of modifications to existing structures rarely have
the necessary prototype data for proper validation. Most model tests rely
on the scaling guidance that has been proven correct by several studies in
which prototype damage has been re-created in a scale model.
Two important aspects of model verification are to assure that waves
and currents produced in the physical model are correctly scaled replicas of
the intended prototype hydrodynamic conditions and the bathymetry is a
reasonable approximation of the prototype. This will help insure the model
is producing the correct response. Just as important is a faithful attempt
to construct the model structure reasonably similar to what exists (or will
exist) in the prototype.
The reliability of rubble-mound stability tests was discussed by Hudson and Davidson (1975) and by T0rum, et al. (1979), and both papers
discussed cases of successful model reproduction of damage that occurred
to actual prototype structures. Hudson and Davidson (1975) compared
damage that occurred to the San Pedro Bay breakwater in 1939 to damage
obtained in a physical model conducted in 1947. Although exact prototype
wave climate was unknown, a reasonable estimate was made for the model,
and prototype-to-model similarity in breakwater cross-section damage led
Hudson and Davidson to conclude that the model was behaving similarly
to the prototype.