Experimental Study and Numerical Simulation of Inclined Rectangular Weirs

Abstract

Inclined rectangular weirs, also named pivot weirs, are used both to adjust the upstream water level and to increase the flow capacity compared with that of normal rectangular weirs. However, the experimental studies available in the literature present contradictory conclusions for the inclined weir discharge capacity. In this paper, new experimental runs and numerical simulations were performed to investigate the effect of the rectangular weir inclination angle on the stage-discharge formula. The experiments were carried out using inclination angles ranging from 3° to 9°. Buckingham’s theorem of dimensional analysis was used to obtain an equation for the flow magnification ratio (the discharge through the pivot weir divided by the corresponding discharge over the vertical weir) as a function of the weir inclination angle. The experimental observations revealed that the flow magnification ratio increases with the inclination angle to a maximum of 1.82 for 3° of inclination. Bidimensional (2D) numerical analysis using the OpenFOAM computational fluid dynamic toolbox was also used. The flow magnification ratios obtained numerically confirmed those obtained experimentally.