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CHAPTER 6. SEDIMENT TRANSPORT MODELS
b. Assume that sediment is reacting primarily to waves with
currents added.
Kamphuis (1975) pointed out that different scale laws are derived, depending upon which assumption is made. Kamphuis believed that waves
move most of the sediment in a coastal model; therefore, the coastal sediment model is basically a short-wave model incorporating empirical relationships between wave action and sediment motion. Unidirectional currents are then added to the waves model, and the scale relationships are
adjusted accordingly to yield valid results for different situations. Thus,
waves must be scaled using the short-wave hydrodynamic model scaling
criteria discussed in Chapter 4, and currents may be distorted to suit the
model. The assumption of a waves model with currents added is adopted
in this chapter.
The important physical parameters involved in coastal sediment transport have been identified (e.g., Kamphuis 1985; Dalrymple 1989) and are
listed below:
Hydrodynamic Parameters :
H - wave height
T - wave period
L - wavelength
A - characteristic length
x,y - horizontal coordinates
z - vertical coordinate
t - time
h - local water depth
g - acceleration of gravity
k3 - bottom roughness
p - fluid density
y - fluid kinematic viscosity
Sediment Parameters :
d - sediment diameter
p3 ~ sediment density
Tb - bottom shear stress
w - sediment fall speed
Sediment fall speed is thought to be a function of sediment grain size,
density and shape, and fluid density and viscosity; therefore, it might be
argued that fall speed is not an independent physical parameter. Bottom
shear stress is not a physical parameter of the sediment; instead it characterizes the linkage between fluid and sediment.
CHAPTER 6. SEDIMENT TRANSPORT MODELS
b. Assume that sediment is reacting primarily to waves with
currents added.
Kamphuis (1975) pointed out that different scale laws are derived, depending upon which assumption is made. Kamphuis believed that waves
move most of the sediment in a coastal model; therefore, the coastal sediment model is basically a short-wave model incorporating empirical relationships between wave action and sediment motion. Unidirectional currents are then added to the waves model, and the scale relationships are
adjusted accordingly to yield valid results for different situations. Thus,
waves must be scaled using the short-wave hydrodynamic model scaling
criteria discussed in Chapter 4, and currents may be distorted to suit the
model. The assumption of a waves model with currents added is adopted
in this chapter.
The important physical parameters involved in coastal sediment transport have been identified (e.g., Kamphuis 1985; Dalrymple 1989) and are
listed below:
Hydrodynamic Parameters :
H - wave height
T - wave period
L - wavelength
A - characteristic length
x,y - horizontal coordinates
z - vertical coordinate
t - time
h - local water depth
g - acceleration of gravity
k3 - bottom roughness
p - fluid density
y - fluid kinematic viscosity
Sediment Parameters :
d - sediment diameter
p3 ~ sediment density
Tb - bottom shear stress
w - sediment fall speed
Sediment fall speed is thought to be a function of sediment grain size,
density and shape, and fluid density and viscosity; therefore, it might be
argued that fall speed is not an independent physical parameter. Bottom
shear stress is not a physical parameter of the sediment; instead it characterizes the linkage between fluid and sediment.