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This figure also shows clearly how the channel bed developed in the asymptotic
state from a near-trapezoidal shape at the bend entrance to a closely triangular
shape with a scour hole near the outer bank and a point bar near the inner bank
in the bend.
Case 2. Sedimentation in the upstream neighborhood of TGP dam
Fang and Rodi (2000) and Fang and Wang (2000) calculated the flow and sediment
transport processes in the neighborhood of Three Gorges dam on the Yangtze River
in a period of 76 years after the dam started operating. This problem was also investi-
gated in a laboratory experiment at Tsinghua University (1996). Fang and Rodi (2000)
applied the 3-D model described in Sections 7.1.3.2 and 7.3 presented by Wu
et al
.
(2000a), while Fang and Wang (2000) used a different 3-D model based on the finite
analytic method. Since both simulation results are similar, only those of Fang and
Rodi (2000) are introduced here. As the sediment transport was almost entirely due
to suspended load, only the suspended-load model was used in the calculation. The
computational domain was a 16.7 km long reach upstream of the dam, as shown in
Fig. 7.7. This domain was represented by a numerical grid that had 234, 42, and
22 points in the streamwise, lateral, and vertical directions, respectively. The initial
Figure 7.7
Calculated surface velocity vectors upstream of TGP dam (Fang and Rodi, 2000).
