Effect of different inlet on some Hydraulic characteristic of octagonal and circular reservoirs

This research aims to investigate the effect of three types of water inlets (one vertical input; two vertical inputs; one vertical & horizontal input) on the rate of water exchange and solid removal in octagonal reservoir (313 liter, without fish). Entering water in all entrances was 0.086 liter per second (water exchange: once per each hour). Salt was used as the tracer in measuring water exchange of reservoirs and the polystyrene was used as the simulator of fish waste. After one hour, in octagonal reservoir with two vertical inputs, salinity was reduced from 20 to 6.40±0.20 ppt and with one vertical & horizontal input from 20 to 6.67±0.05 ppt that had effective in water exchange. And in circular reservoir with vertical & horizontal inputs, salinity was reduced from 20 to 9.30±0.20 ppt that had effective in water exchange. In two reservoirs, discharge rate of polymer granules (waste) over time increased and then decreased. Maximum polymer granules discharge rate was observed in octagonal reservoir with one vertical input (44.20 ± 0.88 g) and in the circular reservoir with one vertical & horizontal input (38.5 ± 3.97 g). The results of the interaction between the input method and the type of reservoirs showed that the most effective input for the water change rate belonged to: one vertical & horizontal input > two vertical inputs > one vertical input, respectively. While the most effective solid removal were: one vertical input> one vertical & horizontal input > two vertical inputs, respectively.