Direct solution for discharge in circular free overfall

SummaryFree overfall at the end of a circular channel is simulated as sharp-crested weir with zero height to get end-depth-discharge relationship. A closed-form equation for discharge in terms of end depth for subcritical flows is proposed and verified with the experimental data. Computed discharges show excellent matching with the observed data. Direct solution for discharge for known end depth, channel bed slope, and Manning’s coefficient is provided in the graphical form for supercritical flow. Verification of this solution with the available experimental data revealed that computed discharges are within ±12% of the observed discharges.

► A closed form equation for discharge in terms of end depth for subcritical flows is proposed.
► Computed discharges show excellent matching with the observed ones.
► Verified with the experimental data revealed that computed discharges are within ±12% of the observed ones.