Pivot weirs have been proved efficient to measure, control and stabilize open channel flows in an easy-to-use manner. This work presents a numerical investigation of free surface overflow from full-width rectangular pivot weirs based on the hydrostatic-corrected smoothed particle hydrodynamics (SPH). In verification stage, the draining process of a reservoir-vertical weir system is separately analyzed by activating and deactivating the hydrostatic correction. The SPH results are benchmarked against a simplified analytical solution derived herein. It is shown that the declining reservoir head is more accurately predicted by activating the correction term. The SPH simulations are then validated for five weir inclination angles, ranging from a very mild to vertical configurations. Comparison with relevant experimental data demonstrates satisfactory agreement in each case. It is observed that the location of vena contracta in the overtopping jet shifts further downstream at steeper inclination angles. Moreover, a simple relation among discharge coefficient and weir inclination angle is proposed based on the curve-fitting of SPH results. These two parameters appeared to be negatively correlated so that an increase in the inclination angle poses a decrease in the discharge coefficient and vice-versa. The present analysis can be useful for estimating flow discharge if a simple head measurement is available for a given geometry of the pivot weir.
