Effect Of Flow Structure In Vertical Slot Fishway On Migratory Behavior Of Schizothorax Prenanti

Fish migration experiment were conducted in three vertical slot fishway with different relative length of lateral baffle P/B to study the migratory behavior of Schizothorax Prenanti in different flow structures,and to analyze the main factors influencing the migratory behavior of Schizothorax Prenanti.The research contents and main conclusions are as follows:(1)The study method of combining physical model test and numerical simulation results to compare the flow structure of fishway with body type ?(P/B=0.1),body type ?(P/B=0.25)and body type ?(P/B=0.5),and to analyze the relevant hydraulic parameters,such as velocity,turbulent kinetic energy,velocity gradient,etc.(2)The fish migration experiment of Schizothorax Prenanti is carried out by means of controlled trial that body type ? as control group.Experiments have been carried out in physical model by dividing into test group ?(body type ? and body type ?)and test group?(body type ? and body type ?).The passing rate and passing time are used as evaluating indexes to compare the fish passing behavior of three vertical slot fishway with different body types.The analysis results showed that the passing efficiency of Schizothorax Prenanti in body type ? and body type ? is significantly better than body type ?.(3)After process the fish video and extract fish migration trail,and consider the characteristics of the flow structure,the influence of different flow structures on the migratory behavior of the fish is analyzed.The results show that fish tend to migrate along the wall because of the foraging habit of scraping the algae attached to the rock;In slot,distribution of fish passing number is negatively related to the velocity,turbulent kinetic energy and velocity gradient,the fish tend to pass through the baffle side with relatively low velocity,turbulent kinetic energy and rapid velocity attenuation.(4)The migratory process of the fish is analyzed:The fish rush through the vertical slot and pass through the main stream under the inertial action;Then,the fish actively searched for the side wall of the pool driven by the foraging habits and migrate along the wall;The velocity and direction of the flow in the area near the vertical slot are quite different from that of the surrounding water,the fish adjust the body direction to face the incoming flow under the effect of rheotaxis;Before passing through the vertical slot,the fish feel the velocity gradient,then immediately moved to the direction of velocity reduction,and select the favorable area on the baffle side to pass through,it can be concluded that the velocity gradient is one of the main factors affect fish position selection.