Gates are useful structures that are widely used in open channels for controlling discharge and water level. In this article, to study the flow passing under a gate, five gates with different-shaped edges are numerically simulated. The contraction coefficient, discharge coefficient, pressure distribution behind the gate, and the pressure distribution on the channel bottom near the gate were investigated with models in free flow conditions. The analyses were performed for six water depths. The results show that the contraction coefficients for standard and jagged-edged shapes increase with an increase in the 𝑎/𝐸1 ratio (where 𝑎 is the gate opening and 𝐸 is the energy level), which matches the experimental results. For upward- and downward-facing sharp edges and for rounded-edged gates, the contraction coefficient decreases until 𝑎/𝐸1 < 0.4 and increases for 𝑎/𝐸1 > 0.4. Investigation of pressure distribution behind the gate and on the bottom of the channel under the gate shows that the position of maximum pressure is the same for all models, but its magnitude varies among different models. Comparison of numerical analysis results with experimental and theoretical data showed good agreement.
