Discharge coefficient of rectangular sharp-crested side weirs Part II: Domínguez's method

• The criticisms about the De Marchi's discharge coefficient formula were discussed.
• The theory of Domínguez was applied for estimating the discharge over the side weirs.
• Merits of the Domínguez's theory to be applied in practice were evaluated based on experimental data.
• It was found that despite the simplicity the Domínguez's theory is more accurate than the De Marchi's theory.
• Finally, novel correlations were derived for calculating the Domínguez's discharge coefficient.

The hydraulic design of a side weir is complicated because the flow conditions vary with distance along the weir, resulting in the 3-D nature of flow over side weirs. Accordingly, by considering the criticism on De Marchi's discharge coefficient formula (Part I), the present study examines a method proposed by Domínguez for estimating the discharge over the side weirs under a subcritical flow condition. Further, on the basis of a comprehensive analysis of the available experimental data, the merits of the practical application of the Domínguez's method were evaluated. The results reveal that the fundamental assumptions of Domínguez, e.g., constant specific energy and linear free surface profile along the side weir in the main channel centerline, are appropriately satisfied. Finally, on the basis of the dimensional analysis, novel correlations were derived for calculating the Domínguez's discharge coefficient with respect to the most significant dimensionless parameters. The estimated results compare well with the results of the model experimentation.