EXPERIMENTAL AND NUMERICAL INVESTIGATION ON OPEN CHANNEL FLOW CHARACTERISTICS

This study presents an experimental and numerical investigation of open channel flow characteristics using rectangular and V-notch weirs. The experiments were conducted on an Armfield Hydraulics Bench to determine the discharge-head relationship and the coefficient of discharge (Cd) for both weir geometries. For each test, the head over the weir was measured at steady flow conditions, and the corresponding discharge was calculated using volumetric measurements. The numerical simulation was performed using HEC-RAS software to reproduce the same flow conditions and evaluate its predictive accuracy.The results showed that discharge increased with increasing head for both weir types, following a power-law relationship of the form. The V-notch weir demonstrated greater sensitivity to small head variations compared to the rectangular weir, making it more suitable for low-flow measurements. The experimental coefficients of discharge ranged between 0.47-0.53 for the rectangular weir and 0.57-0.58 for the V-notch weir, values which were in close agreement with standard literature. Comparison between experimental and numerical results revealed good correlation. Overall, the study confirmed that HEC-RAS can effectively simulate open channel flow behavior and that V-notch weirs provide higher measurement accuracy for small discharges.