Author(s): Hui Ling Wong; Hubert Chanson
Linked Author(s): Hubert Chanson
Keywords: Culvert Turbulence Open Channel Flows Fish Passage Environmental Fluid Mechanics Hydrodynamics Low Velocity Zone CFD Physical Modelling
Abstract: Culverts are water channels designed to pass water through an embankment. Because of the high velocities in culvert barrels, the upstream passage of fish with weak swimming abilities is hindered, particularly for small-bodied native fish species and juveniles of larger fish. Recent studies recommended the use of low velocity zones (LVZ) in the culvert to facilitate upstream fish passage, which are also the fish preferential swimming zone. To date, the knowledge of the turbulence characteristics in the low velocity zones is still insufficient and not considered in the current fish passage guidelines, despite its relevance to fish kinematics. New research was carried out to study turbulence and secondary motion in the low velocity zone of a box culvert. Detailed turbulence measurements were undertaken in a near full-scale box culvert barrel. The results of the physical modelling were compared to some computational fluid dynamics (CFD) modelling using ANSYSTM Fluent. Velocity and Reynolds stress measurements showed some strong secondary motion of Prandtl's second kind. The turbulent characteristics, such as turbulent Reynolds stress and secondary current, were carefully detailed and compared with the CFD model, presenting a novel insight into the turbulence of fish's preferential swimming zone.
Year: 2025