3-D numerical models - Computational River Dynamics - page 308

7.3.4 Examples

Case 1. Sediment transport in an 180 ◦ channel bend
The flow, sediment transport, and bed change processes in an 180 ◦ channel bend inves-
tigated experimentally by Odgaard and Bergs (1988) was simulated by Wu andWenka
(1998), Wu et al . (2000a), and Zeng et al . (2005) using 3-D models. The channel bend
was 80m long and 2.44m wide, connected with 20m long straight sections upstream
and downstream. The cross-section was trapezoidal with vertical sidewalls, and the
channel bed was filled with a 30 cm thick layer of sand with an initially flat surface.
The sand had a median diameter of 0.3mm and a geometric standard deviation of
1.45. The experiment was carried out at a discharge of 0.153m 3 s − 1 with an aver-
age water depth of 0.15m and average velocity of 0.45m s − 1 . The sediment moved ·

cm − 1 min − 1 , as measured

through the channel mainly as bed load at a rate of 3.7 g ·

by a bed-load sampler.
Wu andWenka (1998) andWu et al . (2000a) used the 3-D flowmodel introduced in
Section 7.1.3.2 with the standard k -

ε turbulence closure, whereas Zeng et al . (2005)

used a 3-D flow model with the k - ω turbulence closure. Wu et al . and Zeng et al .

Figure 7.5 Flow depth contours in an 180 ◦ bend: (a) measured by Odgaard and Bergs (1988),
(b) calculated by Zeng et al . (2005), (c) calculated by Wu and Wenka (1998), and
(d) calculated by Wu et al . (2000a).