Numerical Investigation of Flow Dynamics in a Sharp-Crested Weir with Variable Geometry

The diverse flow patterns observed in open channels with weir-type structures are common in natural environments such as rivers. However, the complex flow dynamics in these settings remain only partially understood. To address this research gap, a rectangular sharp-crested weir with variable geometric ratios crest heights (H/P) and widths (H/B) was numerically analyzed using CFD modeling in ANSYS Fluent. The primary objective of this study is to provide detailed numerical insights into flow characteristics over sharp-crested weirs with varying H/P and H/B, where H represents the head over the weir, P the weir height, and B the weir width. Discharge capacity and turbulent intensity profiles and contours were generated and compared across four different cases (Cases A-D). The findings demonstrate that changes in geometric parameters significantly influence flow behavior, particularly by affecting discharge rates and turbulence intensity. These results reveal the presence of complex, wide-ranging flow motions similar to those observed in natural open channels, highlighting the impact of weir geometry on overall flow dynamics.