Discharge coefficients for broad-crested weirs of low aspect ratios

A previously developed theoretical analysis of the discharge coefficient for broad-crested weirs is investigated. Experimentally determined discharge coefficients are presented for a broad-crested weir of small crest width in an attempt to verify the theory, and an investigation of the geometry of the weir crest separation zone using a flow visualization technique is reported. Data from the literature for broad-crested weirs of large crest widths are also analyzed for comparison with the theory.

Correlation between the experimental coefficients and the theory is not evident and the geometry of the crest separation zone is not observed to conform to that assumed by the theory. Probable reasons for the failure of the theory are discussed and variables which should be included in further investigation are indicated.