306
CHAPTER 6. SEDIMENT TRANSPORT MODELS
Nt
Nt
(6.142)
m
It is interesting to note in the above equation that suspended sediment
concentration will be the same in the model as in the prototype provided
the morphological time scale is the same as the hydrodynamic time scale.
Wang, et al. (1990) developed an expression for Nc given as
Nc
Np'N„Nt
(6.143)
where
/(€)
€
sediment immersed relative density
sediment fall speed
a function of the surf similarity parameter
surf similarity parameter
[= tan/Vx/É/fc)
Substitution of Eqn. 6.143 into Eqn. 6.142 produced
NplN^NTy
NzNf^)
(6.144)
By requiring that Nj^ = 1, the hydrodynamic time scale was derived
from
(6.145)
or in terms of scale ratios
-^tan 0 —
or
Nz
Nx
Nz V/2
N„N})
(6.146)
(Nh_\'12
Thus the requirement for equal values of the surf similarity parameter produced a hydrodynamic time scale given by
Nt —
Nx
x/N^
(6.147)
which is the same time scale derived for Hughes’s (1983) distorted model.
CHAPTER 6. SEDIMENT TRANSPORT MODELS
Nt
Nt
(6.142)
m
It is interesting to note in the above equation that suspended sediment
concentration will be the same in the model as in the prototype provided
the morphological time scale is the same as the hydrodynamic time scale.
Wang, et al. (1990) developed an expression for Nc given as
Nc
Np'N„Nt
(6.143)
where
/(€)
€
sediment immersed relative density
sediment fall speed
a function of the surf similarity parameter
surf similarity parameter
[= tan/Vx/É/fc)
Substitution of Eqn. 6.143 into Eqn. 6.142 produced
NplN^NTy
NzNf^)
(6.144)
By requiring that Nj^ = 1, the hydrodynamic time scale was derived
from
(6.145)
or in terms of scale ratios
-^tan 0 —
or
Nz
Nx
Nz V/2
N„N})
(6.146)
(Nh_\'12
Thus the requirement for equal values of the surf similarity parameter produced a hydrodynamic time scale given by
Nt —
Nx
x/N^
(6.147)
which is the same time scale derived for Hughes’s (1983) distorted model.