Chapt10

16 where n is a roughness parameter since the formula

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Unformatted text preview: s clearly not dimensionally consistent, it requires a conversion factor which changes with the system of units used: | e-Text Main Menu | Textbook Table of Contents | Study Guide Chapter 10 Open-Channel Flow 1.0 SI units 1.486 BG units (10.17) Recall that we warned about this awkwardness in Example 1.4. You may verify that is the cube root of the conversion factor between the meter and your chosen length scale: In BG units, (3.2808 ft/m)1/3 1.486.* The Manning formula for uniform-flow velocity is thus V0 (m/s) 1.0 1/2 [Rh (m)]2/3S0 n (10.18) 1.486 1/2 [Rh (ft)]2/3S0 n V0 (ft/s) The channel slope S0 is dimensionless, and n is taken to be the same in both systems. The volume flow rate simply multiplies this result by the area: Uniform flow: Q V0A n 2/3 1/2 ARh S0 (10.19) Experimental values of n (and the corresponding roughness height) are listed in Table 10.1 for various channel surfaces. There is a factor-of-15 variation from a smooth glass surface (n 0.01) to a tree-lined floodplain (n 0.15). Due to the irregularity of typical channel shape...
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This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.

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