Abstract
In the present study, the hysteretic behavior of supercritical flow that can occur in a channel near adjacent structures, including cross-sectional contractions of the channel width, has been investigated experimentally. Three sudden contracting of 5, 10, and 15 cm and a gradual contraction of 15 cm have been used. The flow rates ranged from 250 to 600 Lit/min. These conditions are set within a laboratory flume; first, there is an increase in the initial flow and then a decrease in secondary flow. The results show that by increasing and then decreasing the flow rate, two different behaviors of flow are observed with the same laboratory conditions. The results showed that with increasing the rate of the sudden contraction, the values of relative depths decrease so that with the initial flow, these depths indicate a subcritical regime. In the secondary flow, with the formation of hysteresis, some discharges indicate a supercritical regime. Also, hysteretic behavior increases the relative residual energy. With the sudden contraction of 15 cm, the formation of submerged hydraulic jumps resulted in a lack of hysteresis.