Investigating the Characteristics of the Hydraulic Jump in a Stilling Basin with Netted Perforated Bed

In this research, the effects of a network of holes in the bottom of the stilling basin on the main properties of the hydraulic jump, such as the sequent depths ratio and the jump length, have been studied. First, by mathematical analysis and expansion of  the momentum equation, an equation for the direct calculation of sequent depths ratio was obtained while flow rate in the channel decreased. Using a laboratory flume , equipped with a network of valves under the bed, a series of experiments were conducted in order to study the behavior and characteristics of hydraulic jump, the results of which were compared with the results obtained from classical hydraulic jump on a smooth bed. The Froude number range in this research was between 5.3 and 7.4 and the ratio of the remaining flow at downstream to incoming flow to the channel was between 0.98 to 0.995. Results showed that reducing the flow rate up to two percent in the channel caused decreasing sequent depths ratio by 19 and 12 percent, compared to classical jump and analytical equation, respectively; the jump length decreased by 29 percent, compared to the classical jump.