Modeling of sequent depth ratio for hydraulic jump under sluice gate using baffle block and sill

The sequent depth ratio as one variable of hydraulic jump characteristics under sluice gate were studied experimentally using different configurations simulation of baffle block and sill. Experimental research used fiberglass prototype model as horizontal channel, width (B) = 50 cm, length (L) = 9 m and using sluice gate installed on it, width (b) = 50 cm, thick (t) = 1 cm, height (h) = 80 cm. Two models combination of baffle block as cubic (code K, 43 running) and trapezoidal (code T, 72 running) with different dimension installed as three row, specified location 25 cm after sluice gate. During each running test with variation open gate (a = 1,2,3,4 cm), variation type of baffle block (K1, K2, K3; T1, T2, T3, T4), the sequent depth, velocity distribution and Froude number were measured and analyzed. The result showed that the modeling of sequent depth ratio in term of the initial Froude number gives the better performance for cubic baffle block (K3, sill 2 cm and 2.7 cm, Fr = 0.16 - 0.39) with R² = 0.9945 and trapezoidal baffle block (T4, sill 3.6 cm, Fr = 0.26 - 0.52) with R² = 0.9973. It concluded that using three rows configuration of baffle block (cubic and trapezoidal baffle block) with value of blockage ratio as 50% was appropriate with USBR standard that value blockage ratio "η" do not exceed 0.5 (depend on the width of the block (Wb), spacing between adjacent blocks (S) and the number of baffle blocks).