New stage–discharge relationships for free and submerged sluice gates

The flow movement through a sluice gate is investigated for both free and submerged flow conditions. For free flow condition, the current dimensionless formula, indicated acceptable accuracy; while for submerged flow condition it was modified especially for low submerged condition. In this regard, Buckingham theorem along with the Incomplete Self-Similarity concept was employed and a new stage–discharge relationship was developed accordingly. Also, to achieve a suitable formula for submerged flow condition being accurate in low submergence, the maximum tailwater depth allowing the free flow condition and head loss factor were identified as missing parameters in the functional dimensional equation. Based on employing these parameters the function of Discharge Reduction Factor (DRF) was defined.

► The flow through submerged and free sluice gate is considered.
► Buckingham theorem and Incomplete Self-Similarity concepts were used to develop a new head–discharge relationship.
► New parameters are identified as missing factors in the functional dimensional equation.
► The proposed formula can be used to calibrate the sluice gate flow continuously from free to submerged flow condition.