Characteristics of Hydraulic Jump on The Bed with Permeable Six Legs Elements

Stilling basin is one of the dissipated energy structures in water transfer systems that its dimensions depend on the characteristics of hydraulic jump.In present study, six legs elements have been used in different permeability on basin bed and the changes of shear stress, sequent depth and the length of jump have been investigated. Experiments were conducted in a rectangular flume of 7.5 m long and 0.3 m wide and six legs elements were arranged on the bed of flume with density percent 36, 63 and 100 in such a way that the incoming water jet was just above the elements surface. The incoming Froude number was in the range of 5.3 to 8.1 and during each test the water surface profile and characteristics of hydraulic jump type A were measured. The results indicate that the most reduction of sequent depth ratio and dimensionless length of jump occur when the density of elements is 36%. In this study, relations have been presented for the sequent depth of hydraulic jump and shear force coefficient of bed as a function of the Froude Number for six legs elements.