64. SUSPENSION-DOMINATED MODELS
313
Fowler also noted that irregular wave profile evolution took about twice as
long as profile development occurring with regular wave action.
Finally, Fowler and Hughes (1991) employed Dean’s scaling criteria in a
movable-bed model reproduction of a severe storm that eroded a beach fill
project at Ocean City, Maryland. This was the first time that Dean’s scaling
criteria had been applied to simulate an actual field event. A time sequence
of irregular waves conditions and corresponding water levels obtained in
the field were simulated at a scale of Nl = 7.5 to provide a reasonable
approximation of the storm evolution. The test was conducted without
prior knowledge of the post-storm profile. The eroded model profile showed
remarkable similarity to the measured profile from the field in terms of
total erosion, but details of the profile were not exactly reproduced. It was
speculated that part of the difference might stem from post-storm beach
recovery that occurred prior to measurement of the field profiles.
Example 6.6. Design of Sediment Fall Speed Models
Use Dean’s scaling criteria to design a geometrically undistorted movable-bed
model that will be used to study beach profile response of a beach fill made of quartz
sand having a relative density of ps/p = 2.65 and a median grain size of (dsojp =
0.35 mm. The prototype fluid is saltwater with kinematic viscosity of vp = 0.0119
cm2/s.
The model sediment is to be quartz sand having the same relative density as the
prototype, but a median grain size of (dso)m = 0.12 mm. The freshwater to be used
in the model is assumed to have a kinematic viscosity of vm = 0.0100 cm2/s.
Dean's Undistorted Fall Speed Parameter Model. First, the alert reader will have
recognized that the prototype and model sediment parameters given for this example
are identical to those given in Example 6.5, where the prototype-to-model fall speed
scale was found to be
Nw = 3.36
The required undistorted model length scale is found by rearranging Eqn. 6.155 and
substituting the value for Nw to get
(Ayi = (W = 113
L
N,
1
-----Required time scales (hydrodynamic and morphological) are found from Eqn. 6.153
as
313
Fowler also noted that irregular wave profile evolution took about twice as
long as profile development occurring with regular wave action.
Finally, Fowler and Hughes (1991) employed Dean’s scaling criteria in a
movable-bed model reproduction of a severe storm that eroded a beach fill
project at Ocean City, Maryland. This was the first time that Dean’s scaling
criteria had been applied to simulate an actual field event. A time sequence
of irregular waves conditions and corresponding water levels obtained in
the field were simulated at a scale of Nl = 7.5 to provide a reasonable
approximation of the storm evolution. The test was conducted without
prior knowledge of the post-storm profile. The eroded model profile showed
remarkable similarity to the measured profile from the field in terms of
total erosion, but details of the profile were not exactly reproduced. It was
speculated that part of the difference might stem from post-storm beach
recovery that occurred prior to measurement of the field profiles.
Example 6.6. Design of Sediment Fall Speed Models
Use Dean’s scaling criteria to design a geometrically undistorted movable-bed
model that will be used to study beach profile response of a beach fill made of quartz
sand having a relative density of ps/p = 2.65 and a median grain size of (dsojp =
0.35 mm. The prototype fluid is saltwater with kinematic viscosity of vp = 0.0119
cm2/s.
The model sediment is to be quartz sand having the same relative density as the
prototype, but a median grain size of (dso)m = 0.12 mm. The freshwater to be used
in the model is assumed to have a kinematic viscosity of vm = 0.0100 cm2/s.
Dean's Undistorted Fall Speed Parameter Model. First, the alert reader will have
recognized that the prototype and model sediment parameters given for this example
are identical to those given in Example 6.5, where the prototype-to-model fall speed
scale was found to be
Nw = 3.36
The required undistorted model length scale is found by rearranging Eqn. 6.155 and
substituting the value for Nw to get
(Ayi = (W = 113
L
N,
1
-----Required time scales (hydrodynamic and morphological) are found from Eqn. 6.153
as