CIV E 530 - OPEN-CHANNEL HYDRAULICS
SPRING 2012
LAB No. 5:  UNIFORM FLOW

  1. Prove that the Darcy-Weisbach friction factor is related to Manning's n by the following relation:

    fD = 8gn2 / (k2 R1/3)

    in which fD = Darcy-Weisbach friction factor, g = gravitational acceleration, R = hydraulic radius, and k = constant specific for the system of units, equal to 1 in SI units and 1.486 in U.S. Customary Units. Express the relation in SI and U.S. Customary units.

  2. A trapezoidal concrete-lined channel is being designed on steep terrain with Q = 12 m3/s, b = 1.5 m, z = 1, and n = 0.013.

    • What should be the design bottom slope to keep the Froude number below 2?

    • What should be the bottom slope to keep the Froude number below 1.5?

    • The prevailing terrain slope is S = 0.0073. Would you recommend choosing a design slope of S = 0.0073? If so, why? Or, why not?