CIV E 530 - OPEN-CHANNEL HYDRAULICS
SPRING 2014
HOMEWORK No. 6
- Given the following data for three trapezoidal channels:
Channel | Q (m3/s) | z | So | n | Vmax (m/s) |
1 | 60 | 2 | 0.004 | 0.04 | 1.8 |
2 | 80 | 2.5 | 0.002 | 0.03 | 1.5 |
3 | 75 | 3 | 0.0015 | 0.035 | 1.2 |
in which Vmax = maximum permissible velocity.
What is the design bottom width (with accuracy to within one-tenth of a meter)
required to satisfy the specified maximum permissible velocity? Use ONLINE CHANNEL 01.
- A channel has the following data: Q = 330 cfs, z = 2, n = 0.025, and S = 0.0018. Use ONLINE TRACTIVE FORCE to calculate the bottom width and depth under the following conditions:
- The particles are moderately angular and of size d25 = 0.9 in.
- The particles are of the same size as in (a), but they are moderately rounded.
Report the angle of repose θ for cases (a) and (b). Discuss how the particle shape affects the design.
- A channel has the following data: Q = 60 m3/s, z = 2, n = 0.03, and S = 0.0006.
Use ONLINE TRACTIVE FORCE to calculate the bottom width and depth under the following conditions:
- The particles on the sides
are slightly angular and of size d25 = 35 mm; the particles on the bottom are of size d50 = 5 mm.
- The particles on the sides
are the same as in (a), but the particles on the bottom are smaller, of size d50 = 4 mm.
Both cases (a) and (b) have low content of fine sediment
in the water and the channel sinuosity is none.
Discuss how the bottom particle size affects the design.
- A certain type of lawn has a critical shear stress of 30
N/m2.
The dimensionless Chezy friction factor f is 0.0075.
What is a good estimate of the critical velocity?
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