Discharge Characteristics of Weirs of Finite Crest Length

• Published in: Journal of hydraulic engineering (New York, N.Y.) Vol. 135; no. 12; pp. 1081 - 1085
• Main Authors: Azimi, Amir Hossein, Rajaratnam, N
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01-12-2009
• Subjects: Applied sciences; Buildings. Public works; Computation methods. Tables. Charts; Exact sciences and technology; Hydraulic constructions; Structural analysis. Stresses; TECHNICAL NOTES; Crest; Discharge coefficient; Hydraulics; Weirs; Open channel flow; Flow measurement; Wave crest; Theoretical study; Water flow; Experimental study; Weir
• ISSN: 0733-9429; 1943-7900
• DOI: 10.1061/(ASCE)HY.1943-7900.0000117

This technical note presents a critical analysis flow over weirs of finite crest length, with square-edged or rounded entrance, for free-flow conditions. Using the flow equation for the broad-crested weir with parallel flow in the critical state as the basis, we have defined the discharge coefficient
Cd
, with the head on the weir as the length scale. Based on an extensive analysis of the experimental observations in the literature, we have confirmed the classification of finite crest length weirs into four classes of long-crested, broad-crested, short-crested, and sharp-crested weirs. For the square-edged entrance, we have developed robust correlations for
Cd
when the Weber number is greater than 1. For weirs with a rounded entrance, for which the data set is not that extensive compared to the square-edged case, we have developed good correlations for
Cd
.