Chapt10

P871 here however we simply use one dimensionalflow

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: proof, that the flow over the crest draws down to hmin H/3, the volume flow q Q/b over the crest is approximately H q crest | v v 2 3 | e-Text Main Menu | V2 dh 2g H V2)1/2 dh 1 (2gh H/3 V2 1 2g 3/2 Textbook Table of Contents H 3 | V2 1 2g 3/2 Study Guide (10.52) 690 Chapter 10 Open-Channel Flow Normally the upstream velocity head V 2/(2g) is neglected, so this expression reduces to 1 Sharp-crested theory: 0.81( 2 )(2g)1/2H3/2 3 q (10.53) This formula is functionally correct, but the coefficient 0.81 is too high and should be replaced by an experimentally determined discharge coefficient. Analysis of Broad-Crested Weirs The broad-crested weir of Fig. 10.16b can be analyzed more accurately because it creates a short run of nearly one-dimensional critical flow, as shown. Bernoulli’s equation from upstream to the weir crest yields V2 1 2g Y 2 Vc 2g H 2 If the crest is very wide into the paper, Vc yc gyc from Eq. (10.33). Thus we can solve for V2 1 3g 2H 3 yc Y 2H 3 This result was used without proof to derive Eq. (10.53...
View Full Document

Ask a homework question - tutors are online