This preview shows page 1. Sign up to view the full content.
Unformatted text preview: size” is taken to be the hydraulic diameter, with P
the wetted perimeter — see Fig. 10.2b. Actually, openchannel 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. eText Main Menu  Textbook Table of Contents  Study Guide 662 Chapter 10 OpenChannel 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...
View
Full
Document
This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.
 Spring '08
 Sakar

Click to edit the document details