Environmental Engineering Reference
In-Depth Information
15
10
5
0
0
5
10
15
Grain Froude number (F
gr
)
d
50
= 0.05 mm
d
50
= 0.10 mm
d
50
= 0.30 mm
d
50
= 0.50 mm
Figure 5.23. Variation of
N
with grain Froude number for
Brownlie's predictor.
15
F
r
= 0.08
10
5
F
r
= 0.06
0
0
1
2
3
4
Grain Froude number (F
gr
)
d
35
= 0.07 mm
d
35
= 0.10 mm
d
35
= 0.20 mm
d
35
= 0.30 mm
Figure 5.24. Variation of
N
with
grain Froude number for the
Ackers-White predictor.
1.0
0.8
0.6
0.4
0.2
0
Figure 5.25. Variation of the
grain Froude number
F
gr
with
water depth (Paudel, 2010).
0
0.5
1.0
1.5
2.0
2.5
Water depth (m)
Moreover, the parameter
F
gr
in the Ackers-White method also depends
on the water depth and in a trapezoidal cross-section the velocity changes
together with the water depth on the side slopes. However, calculations
(Figure 5.25) show that the change in water depth has a very small effect
on the parameter
F
gr
and hence can be neglected.
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