Hydraulic model test results of baffle–brush fish pass

Abstract

The flow characteristics (depth, velocity, energy dissipation) of a new baffle–brush fish pass were investigated experimentally in a 2 m wide rectangular flume which has a bed slope of 4% for discharges of 100–550 l/s. In all the experiments, quasi-uniform and sub-critical flow conditions and Froude numbers between 0·17 and 0·23 were observed. The Darcy–Weisbach friction factor was negatively correlated with the relative submergence of the brush elements. Two different characteristic velocity regions were identified, namely the baffle region and the brush region. The turbulence intensities were in the range 38–79% in the baffle zone and 13–31% in the brush zone. The hydraulic test results showed that this type of fish pass can produce adequate flow depth and favourable local flow velocities for the design discharge of 0·2 m2/s (relative submergence of brushes = 1·03), which is suitable for different fish species.

Hydrodynamic Characteristics of Diagonal Brush Fish Pass: Prototype Measurements

“…Immediately behind the brush block, the mean flow velocity is reduced by about 70%, but the flow does not separate, and no recirculation zone forms (Figure 9). However, it can still produce boundary layer separation and form resistance at each bristle scale [25], which cannot be seen in Figure 9. The flow resistance within the brush blocks includes the sum of all the bristles' friction and drag forces.…”

Editorial

“…Kucukali and Hassinger (2018) present rigorous flow and turbulence measurements in an innovative and cost-effective fish pass, which enables migration for a wide range of fish species characterised by high to low swimming capacity. The fish pass combines the features of traditional baffle fishways with those of brush-furnished fishways, without the need for resting pools (Kucukali and Hassinger, 2015). Unlike previous model tests conducted at a reduced scale, those presented by Kucukali and Hassinger (2018) were performed at a scale of 1:1 to avoid viscosity scale effects.…”

Editorial

“…In the paper by Woods (2015), a new catchment-based method is developed to better integrate UK climate change data into design flood estimation and flood risk modelling. The other three papers focus on reporting results from physical modelling studies investigating new methods of scour control at bridge piers (Pagliara et al, 2015), the operating conditions of a new baffle-brush fish pass design (Kucukali and Hassinger, 2015), and the characteristics of air frequency distributions in self-aerated flows (Deng et al, 2015).In the first briefing paper of the issue, Deng et al (2015) present results from an experimental study on the development of selfaerated open channel flows. The process of self-aeration within high-velocity open channel flows has particular relevance to spillway and chute design where the volume of entrained air can have a significant influence on the depth of the flowing water layer generated.…”

“…In the paper by Woods (2015), a new catchment-based method is developed to better integrate UK climate change data into design flood estimation and flood risk modelling. The other three papers focus on reporting results from physical modelling studies investigating new methods of scour control at bridge piers (Pagliara et al, 2015), the operating conditions of a new baffle-brush fish pass design (Kucukali and Hassinger, 2015), and the characteristics of air frequency distributions in self-aerated flows (Deng et al, 2015).…”

“…In their paper, Kucukali and Hassinger (2015) conduct a series of hydraulic tests on a novel baffle-brush fish pass design over a range of flow conditions and submergence depths. The composite design proposed incorporates a side-byside arrangement of super-active (Larinier) baffle and brush-type fish passes with a transitional flow region in between.…”