CE 230-Engineering Fluid Mechanics Lecture # Noncircular conduits Uniform flow in open channels

Replace D in head loss formula by 4A/P=4Rh Relative roughness = ks/4Rh Re=V(4Rh)/ν Then continue as before If the conduit is not circular then we should do the following

Uniform flow in open channels For this flow the deriving force is gravity which means that the channel has to be sloping in the flow direction An empirical equation is used to analyze this type of flow which is called the MANNING EQUATION

terminology A area P wetted perimeter Hydraulic radius = A/P Manning Equation SI units B. units

Find average velocity in the shown concrete lined channel if the Slope is 1 ft in 2000 ft. The depth of flow is 6 ft.

Example “modified” Determine Q if D= 5 ft, slope =0.001, flow depth = 4 ft Concrete sewer