4.2. SHORT-WAVE HYDRODYNAMIC MODELS
103
Hi - height of the incident wave.
△£ - average width of the core material section,
(therefore, AH J AL is the gradient of head
loss through the voids in the core material).
Dp - effective quarrystone diameter (in centimeters)
of the prototype core material, and it is taken as 10%
smaller than quarrystone from the core material
gradation curve.
P - porosity of the core material (0 < P < 1).
It is important to note that Dp must be a prototype stone diameter in centimeters. The parameters Hi and AL can be either both prototype values
or both model values because they form a ratio that should be preserved
in a geometrically undistorted short-wave model.
Keulegan (1973) conducted experiments using stones of nearly equal
diameter having a porosity of about 0.46, and he developed empirical equations based on this value of porosity. However, typical quarry-run core
material has a gradation that gives porosity values between 0.35 - 0.4.
Hudson, et al. (1979) presented a generalized form of Keulegan’s empirical
equations in which the porosity is taken into account as a variable in the
equations. Two equations are given; one that gives wave transmission in the
prototype when the structure Reynolds number, Rn, is greater than 2000,
and energy losses are assumed to be from turbulent dissipation; and the
other that gives wave transmission in the model for when 20 < Rn < 2000,
and viscous dissipation occurs within the structure. These relationships are
as follows:
Rn > 2000
and
20 < 7^ < 2000
/h,\2/3
UL ~1+7m
I i L
and
fiXf3
7"‘“ 1.52 (zufi lofiV
(4.36)
(4.37)
(4.38)
(4.39)
103
Hi - height of the incident wave.
△£ - average width of the core material section,
(therefore, AH J AL is the gradient of head
loss through the voids in the core material).
Dp - effective quarrystone diameter (in centimeters)
of the prototype core material, and it is taken as 10%
smaller than quarrystone from the core material
gradation curve.
P - porosity of the core material (0 < P < 1).
It is important to note that Dp must be a prototype stone diameter in centimeters. The parameters Hi and AL can be either both prototype values
or both model values because they form a ratio that should be preserved
in a geometrically undistorted short-wave model.
Keulegan (1973) conducted experiments using stones of nearly equal
diameter having a porosity of about 0.46, and he developed empirical equations based on this value of porosity. However, typical quarry-run core
material has a gradation that gives porosity values between 0.35 - 0.4.
Hudson, et al. (1979) presented a generalized form of Keulegan’s empirical
equations in which the porosity is taken into account as a variable in the
equations. Two equations are given; one that gives wave transmission in the
prototype when the structure Reynolds number, Rn, is greater than 2000,
and energy losses are assumed to be from turbulent dissipation; and the
other that gives wave transmission in the model for when 20 < Rn < 2000,
and viscous dissipation occurs within the structure. These relationships are
as follows:
Rn > 2000
and
20 < 7^ < 2000
/h,\2/3
UL ~1+7m
I i L
and
fiXf3
7"‘“ 1.52 (zufi lofiV
(4.36)
(4.37)
(4.38)
(4.39)