The Experts below are selected from a list of 5897403 Experts worldwide ranked by ideXlab platform
Hubert Chanson - One of the best experts on this subject based on the ideXlab platform.
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developing cost effective design guidelines for fish friendly box culverts with a focus on small fish
Environmental Management, 2019Co-Authors: Xinqian Leng, Hubert Chanson, Matthews Gordos, Marcus RichesAbstract:Low-level river crossings can have negative impacts on freshwater ecosystems, including blocking upstream fish passage. In order to restore upstream fish passage in culverts, we developed physically-based design methods to yield cost-effective culvert structures in order to maintain or restore waterway connectivity for a range of small-bodied fish species. New guidelines are proposed for fish-friendly multi-cell box culvert designs based upon two basic concepts: (1) the culvert design is optimised for fish passage for small to medium water discharges, and for flood capacity for larger discharges, and (2) low-velocity zones in the culvert barrel are defined in terms of a percentage of the wetted flow area where the local longitudinal velocity component is less than a characteristic fish speed linked to swimming performances of targeted fish species. This approach is novel and relies upon an accurate physically-based knowledge of the entire velocity field in the barrel, specifically the longitudinal velocity map, because fish tend to target low-velocity zone (LVZ) boundaries. The influence of the relative discharge threshold Q1/Qdes, characteristic fish swimming speed Ufish, and percentage of flow area on the size of box culvert structures was assessed. The results showed that the increase in culvert size and cost might become significant for a smooth culvert barrel with Ufish 0.3, when providing 15% flow area with 0 < Vx < Ufish. Similar trends were seen for culvert barrel with recessed cell(s).
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Using small triangular baffles to facilitate upstream fish passage in standard box culverts
Environmental Fluid Mechanics, 2019Co-Authors: Joseph Cabonce, Ramith Fernando, Hang Wang, Hubert ChansonAbstract:A culvert is a covered channel to pass streams and floodwaters through an embankment. The ecological impact of culverts has been recognised, in particular in terms of stream connectivity, but existing guidelines lead often to un-economical culvert design. Herein, a small triangular corner baffle system was tested physically in a near-full-scale fish-friendly facility of a box culvert barrel. Experiments were repeated with several configurations to characterise the flow properties for a range of less-than-design flows, baffle sizes and spacings. In presence of triangular corner baffles, the flow was asymmetrical, owing to the wake behind each baffle. The presence of triangular corner baffles had a moderate effect on the flow resistance and discharge capacity, albeit the data indicated the combined effect of relative baffle height and spacing on the friction factor. With triangular baffles, the surface area of slow velocity regions increased by a factor of two to three. Such low velocity regions are preferential swimming zones for fish, beneficial to small-bodied fish passage. Testing with small-bodied fish showed that fish preferred to swim upstream in slow-velocity regions, typically next to the sidewalls and in the left corner where the triangular baffles were located. The presence of small triangular baffles facilitated substantially the upstream passage of small fish, including in terms of endurance, compared to a smooth un-baffled box culvert barrel, when the baffle size was comparable to the fish length. The present findings highlighted the importance of physical modelling at near full-scale for the development of fish-friendly culvert designs.
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ventilated corner baffles to assist upstream passage of small bodied fish in box culverts
Journal of Irrigation and Drainage Engineering-asce, 2018Co-Authors: Joseph Cabonce, Hang Wang, Hubert ChansonAbstract:Standard box-culvert designs are similar to ancient designs. The acknowledgment of the ecological impact of culverts and road crossings on rivers has led to changes in culvert design guidelines. A small triangular corner baffle system was tested to assist upstream passage of small body-mass fish in box-culvert structures on a flat bed slope. The study was conducted in a near full–scale physical facility, which had a width of 0.5 m and a length of 12 m. The investigation presented a detailed characterization of the flow field. Tests showed that small-bodied fish preferred to swim in slow-velocity regions (i.e., in the baffles’ corner). The most effective baffles had heights comparable to fish length. A key outcome of the study is the adverse impact of strong flow reversal on small-bodied fish, because strong flow reversal may confuse small-bodied fish attempting upstream culvert passage. A remedial measure is the ventilation of baffles, tested successfully herein.
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alternative mitigation measures for fish passage in standard box culverts physical modelling
Journal of Hydro-environment Research, 2017Co-Authors: Hang Wang, Warren Uys, Hubert ChansonAbstract:Road crossings and culverts are common man-made structures along river courses, ranging from national highways to rural roads and urban networks. Present expertise in culvert hydraulic design is deficient because many empirically-based guidelines are often inadequate for fish passage. This project focused on the development of simple solutions for box culverts, with the aim to maximise slow flow regions suitable for small-bodied fish passage and to minimise the reduction in discharge capacity. Herein a physical study of box culvert was performed under controlled flow conditions, and seven designs were tested. In all the cases, the turbulence of the flowing waters was used to assist with fish migration. One baffle configuration presented promising results: i.e., small corner baffles. The triangular baffle system produced little additional afflux, while creating excellent recirculations both upstream and downstream of each baffle. Another configuration was based upon a rough bed and sidewall, enhancing secondary currents and recirculation in the corner region. This resulted in flow conditions that could be potentially used to enhance small-bodied fish passage, though further experiments involving detailed fish behaviour study are required for quantitative guidelines.
John C Montgomery - One of the best experts on this subject based on the ideXlab platform.
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the flow fields involved in hydrodynamic imaging by blind mexican cave fish astyanax fasciatus part ii gliding parallel to a wall
The Journal of Experimental Biology, 2010Co-Authors: Shane P Windsor, Stuart Norris, Stuart Cameron, Gordon D Mallinson, John C MontgomeryAbstract:Blind Mexican cave fish ( Astyanax fasciatus ) are able to sense detailed information about objects by gliding alongside them and sensing changes in the flow field around their body using their lateral line sensory system. Hence the fish are able to build hydrodynamic images of their surroundings. This study measured the flow fields around blind cave fish using particle image velocimetry (PIV) as they swam parallel to a wall. Computational fluid dynamics models were also used to calculate the flow fields and the stimuli to the lateral line sensory system. Our results showed that characteristic changes in the form of the flow field occurred when the fish were within approximately 0.20 body lengths (BL) of a wall. The magnitude of these changes increased steadily as the distance between the fish and the wall was reduced. When the fish were within 0.02 BL of the wall there was a change in the form of the flow field owing to the merging of the boundary layers on the body of the fish and the wall. The stimuli to the lateral line appears to be sufficient for fish to detect walls when they are 0.10 BL away (the mean distance at which they normally swim from a wall), but insufficient for the fish to detect a wall when 0.25 BL away. This suggests that the nature of the flow fields surrounding the fish are such that hydrodynamic imaging can only be used by fish to detect surfaces at short range. * BL : body length CFD : computational fluid dynamics C f : skin friction coefficient C P : coefficient of pressure d : distance of the fish body from the wall P : pressure field PIV : particle image velocimetry Re : Reynolds number U norm : normalised velocity field Δ C P : normalised pressure difference across canal pores Δ P : pressure difference
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the flow fields involved in hydrodynamic imaging by blind mexican cave fish astyanax fasciatus part i open water and heading towards a wall
The Journal of Experimental Biology, 2010Co-Authors: Shane P Windsor, Stuart Norris, Stuart Cameron, Gordon D Mallinson, John C MontgomeryAbstract:Blind Mexican cave fish ( Astyanax fasciatus ) sense the presence of nearby objects by sensing changes in the water flow around their body. The information available to the fish using this hydrodynamic imaging ability depends on the properties of the flow field it generates while gliding and how this flow field is altered by the presence of objects. Here, we used particle image velocimetry to measure the flow fields around gliding blind cave fish as they moved through open water and when heading towards a wall. These measurements, combined with computational fluid dynamics models, were used to estimate the stimulus to the lateral line system of the fish. Our results showed that there was a high-pressure region around the nose of the fish, low-pressure regions corresponding to accelerated flow around the widest part of the body and a thick laminar boundary layer down the body. When approaching a wall head-on, the changes in the stimulus to the lateral line were confined to approximately the first 20% of the body. Assuming that the fish are sensitive to a certain relative change in lateral line stimuli, it was found that swimming at higher Reynolds numbers slightly decreased the distance at which the fish could detect a wall when approaching head-on, which is the opposite to what has previously been expected. However, when the effects of environmental noise are considered, swimming at higher speed may improve the signal to noise ratio of the stimulus to the lateral line. * ALE : arbitrary Lagrangian–Eulerian BL : body length CFD : computational fluid dynamics C f : skin friction coefficient C P : coefficient of pressure P : pressure field PIV : particle image velocimetry Re : Reynolds number u : velocity field u t : tangential velocity U : swimming speed of the fish U norm : normalised velocity field y : direction normal to the surface Δ C P : normalised pressure difference across canal pores ∇ C P : gradient of the normalised pressure μ : the dynamic viscosity of the fluid ρ : the density of the fluid τw : wall shear stress
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the mechanosensory lateral line system of the hypogean form of astyanax fasciatus
Environmental Biology of Fishes, 2001Co-Authors: John C Montgomery, Sheryl Coombs, Cindy F BakerAbstract:The mechanosensory lateral line is a distributed, hair-cell based system which detects the water flow regime at the surface of the fish. Superficial neuromasts densely scattered over the surface of some cave fish detect the pattern of flow over the surface of the body and are important in rheotactic behaviors and perhaps in the localization of small vibrating sources. Canal neuromasts are very likely also involved in the detection of small planktonic prey, but seem also to play an essential role in replacing vision as the major sense by which blind cave-fish perceive their surroundings. The flow-field that exists around a gliding fish is perturbed by objects in the immediate vicinity, these perturbations are detected by the lateral line system. In this way the fish can build up a ‘picture’ of its environment, a process that has been called active hydrodynamic imaging. None of the lateral line behaviors exhibited by blind cave fish are necessarily exclusive to these species, but there is some evidence that their lateral line capabilities are enhanced with respect to their sighted relatives.
Marcus Riches - One of the best experts on this subject based on the ideXlab platform.
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developing cost effective design guidelines for fish friendly box culverts with a focus on small fish
Environmental Management, 2019Co-Authors: Xinqian Leng, Hubert Chanson, Matthews Gordos, Marcus RichesAbstract:Low-level river crossings can have negative impacts on freshwater ecosystems, including blocking upstream fish passage. In order to restore upstream fish passage in culverts, we developed physically-based design methods to yield cost-effective culvert structures in order to maintain or restore waterway connectivity for a range of small-bodied fish species. New guidelines are proposed for fish-friendly multi-cell box culvert designs based upon two basic concepts: (1) the culvert design is optimised for fish passage for small to medium water discharges, and for flood capacity for larger discharges, and (2) low-velocity zones in the culvert barrel are defined in terms of a percentage of the wetted flow area where the local longitudinal velocity component is less than a characteristic fish speed linked to swimming performances of targeted fish species. This approach is novel and relies upon an accurate physically-based knowledge of the entire velocity field in the barrel, specifically the longitudinal velocity map, because fish tend to target low-velocity zone (LVZ) boundaries. The influence of the relative discharge threshold Q1/Qdes, characteristic fish swimming speed Ufish, and percentage of flow area on the size of box culvert structures was assessed. The results showed that the increase in culvert size and cost might become significant for a smooth culvert barrel with Ufish 0.3, when providing 15% flow area with 0 < Vx < Ufish. Similar trends were seen for culvert barrel with recessed cell(s).
Xinqian Leng - One of the best experts on this subject based on the ideXlab platform.
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developing cost effective design guidelines for fish friendly box culverts with a focus on small fish
Environmental Management, 2019Co-Authors: Xinqian Leng, Hubert Chanson, Matthews Gordos, Marcus RichesAbstract:Low-level river crossings can have negative impacts on freshwater ecosystems, including blocking upstream fish passage. In order to restore upstream fish passage in culverts, we developed physically-based design methods to yield cost-effective culvert structures in order to maintain or restore waterway connectivity for a range of small-bodied fish species. New guidelines are proposed for fish-friendly multi-cell box culvert designs based upon two basic concepts: (1) the culvert design is optimised for fish passage for small to medium water discharges, and for flood capacity for larger discharges, and (2) low-velocity zones in the culvert barrel are defined in terms of a percentage of the wetted flow area where the local longitudinal velocity component is less than a characteristic fish speed linked to swimming performances of targeted fish species. This approach is novel and relies upon an accurate physically-based knowledge of the entire velocity field in the barrel, specifically the longitudinal velocity map, because fish tend to target low-velocity zone (LVZ) boundaries. The influence of the relative discharge threshold Q1/Qdes, characteristic fish swimming speed Ufish, and percentage of flow area on the size of box culvert structures was assessed. The results showed that the increase in culvert size and cost might become significant for a smooth culvert barrel with Ufish 0.3, when providing 15% flow area with 0 < Vx < Ufish. Similar trends were seen for culvert barrel with recessed cell(s).
Shane P Windsor - One of the best experts on this subject based on the ideXlab platform.
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the flow fields involved in hydrodynamic imaging by blind mexican cave fish astyanax fasciatus part ii gliding parallel to a wall
The Journal of Experimental Biology, 2010Co-Authors: Shane P Windsor, Stuart Norris, Stuart Cameron, Gordon D Mallinson, John C MontgomeryAbstract:Blind Mexican cave fish ( Astyanax fasciatus ) are able to sense detailed information about objects by gliding alongside them and sensing changes in the flow field around their body using their lateral line sensory system. Hence the fish are able to build hydrodynamic images of their surroundings. This study measured the flow fields around blind cave fish using particle image velocimetry (PIV) as they swam parallel to a wall. Computational fluid dynamics models were also used to calculate the flow fields and the stimuli to the lateral line sensory system. Our results showed that characteristic changes in the form of the flow field occurred when the fish were within approximately 0.20 body lengths (BL) of a wall. The magnitude of these changes increased steadily as the distance between the fish and the wall was reduced. When the fish were within 0.02 BL of the wall there was a change in the form of the flow field owing to the merging of the boundary layers on the body of the fish and the wall. The stimuli to the lateral line appears to be sufficient for fish to detect walls when they are 0.10 BL away (the mean distance at which they normally swim from a wall), but insufficient for the fish to detect a wall when 0.25 BL away. This suggests that the nature of the flow fields surrounding the fish are such that hydrodynamic imaging can only be used by fish to detect surfaces at short range. * BL : body length CFD : computational fluid dynamics C f : skin friction coefficient C P : coefficient of pressure d : distance of the fish body from the wall P : pressure field PIV : particle image velocimetry Re : Reynolds number U norm : normalised velocity field Δ C P : normalised pressure difference across canal pores Δ P : pressure difference
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the flow fields involved in hydrodynamic imaging by blind mexican cave fish astyanax fasciatus part i open water and heading towards a wall
The Journal of Experimental Biology, 2010Co-Authors: Shane P Windsor, Stuart Norris, Stuart Cameron, Gordon D Mallinson, John C MontgomeryAbstract:Blind Mexican cave fish ( Astyanax fasciatus ) sense the presence of nearby objects by sensing changes in the water flow around their body. The information available to the fish using this hydrodynamic imaging ability depends on the properties of the flow field it generates while gliding and how this flow field is altered by the presence of objects. Here, we used particle image velocimetry to measure the flow fields around gliding blind cave fish as they moved through open water and when heading towards a wall. These measurements, combined with computational fluid dynamics models, were used to estimate the stimulus to the lateral line system of the fish. Our results showed that there was a high-pressure region around the nose of the fish, low-pressure regions corresponding to accelerated flow around the widest part of the body and a thick laminar boundary layer down the body. When approaching a wall head-on, the changes in the stimulus to the lateral line were confined to approximately the first 20% of the body. Assuming that the fish are sensitive to a certain relative change in lateral line stimuli, it was found that swimming at higher Reynolds numbers slightly decreased the distance at which the fish could detect a wall when approaching head-on, which is the opposite to what has previously been expected. However, when the effects of environmental noise are considered, swimming at higher speed may improve the signal to noise ratio of the stimulus to the lateral line. * ALE : arbitrary Lagrangian–Eulerian BL : body length CFD : computational fluid dynamics C f : skin friction coefficient C P : coefficient of pressure P : pressure field PIV : particle image velocimetry Re : Reynolds number u : velocity field u t : tangential velocity U : swimming speed of the fish U norm : normalised velocity field y : direction normal to the surface Δ C P : normalised pressure difference across canal pores ∇ C P : gradient of the normalised pressure μ : the dynamic viscosity of the fluid ρ : the density of the fluid τw : wall shear stress