Experimental Study of Hysteretic Behavior of Supercritical Regime on Hydraulic parameters of Flow against Gabion Contraction

In the present study, the hydraulic characteristics of the flow and the phenomenon of flow hysteresis with the supercritical regime, which can appear in the vicinity of the additional structures in the flow path, such as contracting of the cross-section of the channel, were investigated experimentally. To achieve the objectives of the study, two average diameters of materials inside the gabion basket with sizes of 1.28 and 2.08 cm were used. The inlet flow rate increased in the primary flow and decreased in the secondary flow in the range of 300 to 650 liters per minute. The results of the present study show that by increasing the flow rate and then decreasing the flow, two different behaviors and regimes of flow are observed in the same experimentally conditions. So that with the formation of the phenomenon of hysteresis, the relative depths of the flow were increased by 69.39% and the Froude number of the gabion contraction section has increased significantly by 69.15% and the main cause of the hysteretic behavior of the flow is the current behavior of the flow following its previous behavior. On the other hand, the rate of flow energy dissipation in the use of gabion basket has increased by a relative amount of 71.35% compared to simple contracting. The results also showed that by increasing the size of the constriction and increasing the average diameter of materials in the gabion basket increases energy dissipation and relative downstream depth.