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Abstract: Upstream migration of fish through circular culverts is often prevented by velocities in the barrel being higher than that of the natural channel. In this investigation a computational fluid dynamic (CFD) model has been used to test the effects of various spoiler baffle geometries in culverts of varying size to reduce water velocity and increase water depth and thus increase the upstream passage of small fish species. Results indicated that standard baffles designed for specific fish species or groups could be successfully retrofitted to culverts of varying dimensions. Subsequent field tests have confirmed the effectiveness of the design. [Copyright &y& Elsevier]

Although waterway connectivity is a requirement for all freshwater fish, culverts have had negative impacts on freshwater river ecology. Following a recent biological study suggesting that asymmetrical wall baffles may be conducive to upstream passage of small-bodied fish, experimental modeling of plain wall baffles on one sidewall only was conducted under controlled flow conditions. The measurements were performed in a 15-m-long, 0.5-m-wide culvert barrel channel at several longitudinal and transverse locations for a broad range of discharges and baffle geometries to deliver a fine characterization of the hydrodynamics of the asymmetrically baffled channel. The physical modeling data illustrated the drastic impact of a seemingly simple boundary treatment (i.e., plain rectangular baffles) on the flow field. In practice, the installation of baffles has practical engineering implications that must not be ignored. [ABSTRACT FROM AUTHOR]