The Afflux Calculation Under Effect of Different Number of Vents Experimentally and Using HEC-RAS

Abstract

The effect of vents’ number in bridges for the same contraction ratio was not taken into consideration in many calculation formulas of afflux. The present paper investigates the influence of vents’ number on the calculation of the afflux through bridge for the same contraction ratio. The paper experimentally and numerically modeled the water surface profile through the bridge vents to calculate the afflux. The experimental measurements include two stages, the first stage includes the use of a single pier model with a length of 14.7 cm and a width of 2.3 cm. The second stage includes the presence of two piers of 14.7 cm length and 1.15 cm width for each one. The numerical modeling was done using one-dimensional River Analysis System (HEC-RAS). The results showed that the afflux ratio increased as Froude number increased. The increasing of vents’ number for the same contraction ratio increases the afflux. The case of contraction ratio = 0.623 gives the higher values of the afflux ratio comparing other contraction ratios. The numerical modeling is promising compared the experimental measurements.

Keywords

• bridges
• contraction ratio
• afflux
• piers
• hec-ras