Study On The Simulation Of Fish Migratory Trajectory In A Vertical Slot Fishway

Vertical slot fishway serves as an artificial passage for fish migration and plays an important role in the entire river ecosystem.At present,the research about vertical slot fishway focuses on hydraulics calculation,ignoring the fish's own swimming characteristics and various ability indicators.Therefore,vertical slot fishway can still be optimized in the future.To improve fishway passage efficiency,grass carp is used as the research object of this paper,through laboratory test and numerical calculation method,the problem that the hydraulics of vertical slot fishway how to influent the migration of fish is explored and researched,and get the following conclusions:?1?With the high-precision variable slope tank to carry out relevant fish test,fishway passage efficiency reached 63.4%,indicating that vertical slot fishway structure designed in test is reasonable,and the flow pattern of vertical slot fishway model basically could meet the demand of fish.?2?Through the model test,hydraulic characteristics of the same side vertical slot fishway are analyzed.It is concluded that flow velocity ranges from about 1.0to 1.2 m·s^-1 near slot.The flow diffuses and the mainstream velocity gradually decreases.Due to the obstruction of the long baffle,the main streamline changes,forming a mainstream band similar to the"S"type,and the distribution of the flow velocity is more obvious.Two recirculation zones with asymmetrical size and position are formed at the near side walls on both sides of the mainstream area,which provides a favorable rest space for the fish's migration behavior.Due to the large fluctuation in the mainstream area,the velocity gradient changes significantly,leading to the turbulence kinetic energy in the mainstream area is generally higher than the turbulence kinetic energy in the recirculation zone;the distribution characteristics of the shear stress of Reynolds are consistent with the turbulence kinetic energy distribution.?3?The preference value of Ctenopharyngodon idellus for velocity during the migration is 0.1⁰.2 m·s^-1;the preference value of fish for turbulent kinetic energy during migration is 0.02⁰.03 m²·s^-2;Ctenopharyngodon idellus will preferentially choose the area where turbulence intensity is 0.125⁰.175 to migrate.Higher or lower turbulent conditions are not conducive to migration behavior of Ctenopharyngodon idellus.For Reynolds shear stress,Ctenopharyngodon idellus is preferentially selected from 0⁰.01 N·m^-2.With the increase of Reynolds shear stress,the proportion is also smaller and smaller;the turbulent dissipation rate of20%⁶0%of migration path is 0⁰.05 m²·s^-3.Within the range;Ctenopharyngodon idellus has the highest regional selectivity for variability values of approximately10 s^-1.In addition,the order of influence of each hydraulic factor on fish is:turbulence intensity>turbulent kinetic energy>horizontal Reynolds shear stress>velocity>turbulent dissipation rate>Reynolds shear stress in other directions>strain rate.?4?Based on the preference thresholds and weight values of each hydraulic factor,the migration direction of fish is calculated.The relationship between the swimming speed and the flow velocity is established.The model is embedded in the dynamic motion speed,and the fish is in time by integrating the swimming speed with time.The individual fish migration movement model in the vertical slot fishway was established and the trajectory of fish was simulated and predicted,which confirmed the model is reliable and universal.