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CHAPTER 4. HYDRODYNAMIC MODELS
In the above equations, the structure Reynolds number (ÆJ is calculated
as
PHiLD
Rn " 2vhT
and the variables are defined as
Hi - incident wave height
Ht - transmitted wave height
L - incident wavelength
h - water depth
T - wave period
v - kinematic viscosity
D - characteristic dimension (10 % smaller) of
quarrystone core material
AL - average width of the core material section
g - gravitational acceleration
P - porosity of the core material
The velocity used in the Reynolds number is
v
'seepage — ^hT
(4.40)
(4-41)
and it represents the maximum seepage velocity at the entrance face of
the structure. Keulegan (1973) derived this velocity for a uniform shallow
water wave whose amplitude decreases exponentially through the porous
structure.
Keulegan’s prototype equations (Eqns. 4.36 and 4.37) are used with
prototype parameters to determine the prototype-scale wave transmission.
Because similarity of wave transmission requires that
Ht\
ha
Ht)
(4-42)
m
the same wave transmission ratio is used in the model equations (Eqns. 4.38
and 4.39), along with model parameters to determine the value for Dm. The
values of Dp and Dm can be placing into Eqn. 4.34 to find the value of the
factor A. As previously mentioned, current guidance is to average the
K-values found using the Le Méhauié and the Keulegan methods.
Additional information on scale models of rubble structures is given in
Sharp and Khader (1984) and in Chapter 5 (Stability Models).