Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.

Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 69

69
Z
X Y
Block 4 Block 3
0
Block 1
-0.2
Z/(0.5B1)
-2
-0.4
0
2
0 1) Block 2
0.25 4 0. 5B
X /(
Y /( 0.5
0 .5 6
B1 0.75
) 8 Center of the channel
1
Figure 8.1. Grid system for the simulation in the case of B2/B1 = 0.25.
also observed that the distance xmax between the beginning of was 0.45 m. The upstream flow was a steady flow with a
the fully contracted section and the location of max increases velocity of 0.45 m/s, the contraction channel ratio (B2/B1)
when increases was equal to 0.5, the transition angle was 90 degrees, and the
water depth was 0.12 m. Four different contraction lengths
8.4 CONTRACTED LENGTH EFFECT: were simulated: L/(B1 - B2) = 0.25, 0.5, 1.0 and 6.76. The
NUMERICAL SIMULATION RESULTS difference (B1 - B2) was chosen as the characteristic length
B. The Reynolds Number was 101250 and the Froude Number
Again, one of the flume experiments was chosen to per- was 0.303. The initial bed shear stress distribution around the
form the numerical simulation. The width of the flume used contracted zone is shown in Figures 114 to 116 for various
1 8.50
4.51
6.92 8.12 6.92
Center of channel
3.31 5.71
9.32 4.51
0.91
0.75 2.11
= 0.91
Y/(0.5B1)
0.5 Abutment
Flow
0.25
0
-1 -0.5 0 0.5
X/(0.5B1)
Figure 8.2. Initial bed shear stress distribution (N/m2) for B2/B1 = 0.25
and V = 0.45m/s.

OCR for page 69

70
1
3.29
Center of channel 3.11
3.29
2.49
0.75 1.25
1.70
2.49
1.70
Y/(0.5B1)
= 0.91 4.08
0.91
0.5
Abutment
0.25 Flow
0
-1 -0.5 0 0.5
X/(0.5B1)
Figure 8.3. Initial bed shear stress distribution (N/m2) for B1/B2 = 0.50
and V = 0.45m/s.
1
2.18
Center of channel
0.75 1.54 1.78 2.03
= 1.29
2.33
Y/(0.5B1)
0.5 2.03
2.66
1.78
1.54
3.00 1.29
0.91
Flow
0.25
0.91
Abutment
0
-1 -0.5 0 0.5
X/(0.5B1)
Figure 8.4. Initial bed shear stress distribution (N/m2) for B2/B1 = 0.75,
and V = 0.45m/s.
1 1.83
Center of channel 1.68 1.68
1.06 1.52
0.75
1.37 1.68
= 0.91 1.22
1.99
Y/(B1-B2)
2.45
0.5
Flow
0.25 Abutment
0
-3 -2 -1 0 1 2
X/(B1-B2)
Figure 8.5. Initial bed shear stress distribution (N/m2) for B2/B1 = 0.5,
V = 0.45 m/s, L/(B1 B2) = 6.76, and = 15 degrees).

OCR for page 69

71
1
2.06
1.49
Center of channel 1.10 1.87 1.68
1.49 1.87
0.75
2.06
= 0.91
2.25
Y/(B1-B2)
3.17
0.5
Flow
0.25 Abutment
0
-3 -2 -1 0 1 2
X/(B1-B2)
Figure 8.6. Initial bed shear stress distribution (N/m2) for B2/B1 = 0.5,
V = 0.45 m/s, L/(B1 B2) = 6.76, and = 30 degrees).
1 2.27 2.02
1.36 2.27
Center of channel
1.82 2.02
0.75
2.62
Y/(B1-B2)
= 0.91 3.76
0.5
0.25 Flow
Abutment
0
-3 -2 -1 0 1 2
X/(B1-B2)
Figure 8.7. Initial bed shear stress distribution (N/m2) for B2/B1 = 0.5,
V = 0.45 m/s, L/(B1 B2) = 6.76, and = 45 degrees).
1
3.25
Center of channel 3.25
1.97 3.02
2.49
0.75 1.44 3.02
3.44
= 0.91
3.75
1.97
Y/(B1-B2)
4.04 0.91
0.5
Flow
0.25 Abutment
0
-1 -0.5 0 0.5
X/(B1-B2)
Figure 8.8. Initial bed shear stress distribution (N/m2) for B2/B1 = 0.5,
V = 0.45 m/s, and L/(B1 B2) = 0.25).