V-notch Discharge Coefficient Prediction for Different Hydraulic and Geometric Characteristics

Abstract

The purpose of this study was to develop formulas to predict the V-notch discharge coefficient, C_d, for different hydraulic and geometric characteristics. To achieve this purpose, 20 V-notch models were constructed with four vertex angles, θ, of 30º, 45º, 60º, and 90º; five V-notch heights, p, of 4, 6, 8, 10, and 12 cm; and four thicknesses, t, of 1, 3, 4, and 6 mm. Experimental runs were conducted using six water heads, h, for each V-notch model. The results indicated that the V-notch discharge coefficient, C_d, depends on its hydraulic and geometric characteristics. It was found that the discharge coefficient, C_d, is directly proportional to the water head ratio, h/p, and inversely proportional to each V-notch vertex angle, Ɵ, and thickness, t/p. Formulas for predicting the V-notch discharge coefficient, C_d, were developed for different vertex angles, Ɵ, and then the predicted values of the discharge coefficient, C_d, using the developed formulas were plotted against the calculated values with a coefficient of determination (R² = 0.9372), showing a good agreement between the predicted and measured values.