Since channels are irregular in shape their size is

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Unformatted text preview: size” is taken to be the hydraulic diameter, with P the wetted perimeter — see Fig. 10.2b. Actually, open-channel formulas typically use the hydraulic radius Rh 1 Dh 4 A P (10.4) The local Reynolds number of the channel would be Re VDh/ , which is usually highly turbulent ( 1 E5). The only commonly occurring laminar channel flows are the thin sheets which form as rainwater drains from crowned streets and airport runways. The wetted perimeter P (see Fig. 10.2b) includes the sides and bottom of the channel but not the free surface and, of course, not the parts of the sides above the water level. For example, if a rectangular channel is b wide and h high and contains water to depth y, its wetted perimeter is P | v v not 2b | b 2y (10.5) 2h. e-Text Main Menu | Textbook Table of Contents | Study Guide 662 Chapter 10 Open-Channel Flow Although the Moody chart (Fig. 6.13) would give a good estimate of the friction factor in channel flow, in practice it is seldom used. An alternate correlation due to Robert Manning, di...
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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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