Environmental Engineering Reference
In-Depth Information
- reference concentration
c
a
0
.
015
d
50
T
1
.
5
aD
∗
c
a
=
(A.33)
0
.
3
- reference level
a
a
=
0
.
5
or
a
=
k
s
with
a
min
=
0
.
01
h
(A.34)
- representative particle size of suspended sediment
d
s
d
s
=
[1
+
0
.
011(
σ
s
−
1)(
T
−
25)]
d
50
(A.35)
where:
F
=
shape factor
V
=
mean velocity (m/s)
u
∗
=
shear velocity (m/s)
c
a
=
reference concentration
h
=
water depth (m)
D
∗
=
particle parameter
=
a
reference level (m)
=
Z
suspension number
Z
=
modified suspension number
β
=
ratio of sediment and fluid mixing coefficient
ψ
=
stratification correction
κ
=
constant of von Karman
σ
s
=
geometric standard deviation
d
50
=
median diameter (mm)
d
s
=
representative particle size of suspended sediment (m)
w
s
=
fall velocity of representative particle size (m/s)
T
=
transport stage parameter
=
bed form height (m)
k
s
=
equivalent roughness height (m)
u
∗
,cr
=
critical bed shear velocity (m/s)
A.6 YANG METHOD
The method proposed by Yang (1973) is based on the hypothesis that the
sediment transport in a flow should be related to the rate of energy dissi-
pation. The rate of energy dissipation is defined as the unit stream power
and can be expressed by the velocity times slope (
V
S
). The theoretical
basis for Yang's unit stream power is provided by the turbulence theory.
By integrating the rate of turbulence energy production over the depth,
the suspended sediment transport can be expressed as function of the unit
stream power.
∗
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