Due to the high flow velocity downstream of the hydraulic structures including dam spillways and chutes, proper structures are needed to dissipate the flow destructive kinetic energy by establishing a controlled hydraulic jump, thereby protecting the downstream hydraulic systems. One of the most common hydraulic structures to control as well as to dissipate the flow destructive kinetic energy, is the hydraulic jump-type stilling basins. To achieve an optimum performance, an effusively controlled hydraulic jump must be occurred within the stilling basin. Therefore, study of the stilling basins including In the present study, we investigated the effects of different geometrical and hydraulic aspects of flow including the nozzle height from the basin bottom, the nozzle diameter and the downstream control weir height on hydraulic characteristics of the circular hydraulic jumps, based on model experimentation. Experiments were performed in a cubic reservoir at the Hydrodynamic Laboratory of the Submarine Science and Technology Research Institute, Isfahan University of Technology, having the dimensions of 2.5´2.5 m 2 and a height of 1.5 m. Inside the reservoir, a circular plate, 2 m in diameter is installed as the circular stilling basin bottom. According to their characteristics, different types of free and submerged circular hydraulic jumps were Keywords : Circular hydraulic jump, stilling basins, Types of jump,submerged hydraulic jump
