Turbulence characteristics of flow in a spiral corrugated culvert fitted with baffles and implications for fish passage

Baffles are often used to retrofit culverts to aid in fish passage. The objective of this experimental investigation was to compare the turbulent flow structure inside a full-scale spiral corrugated culvert fitted with sloped- and slotted-weir baffles to available turbulence descriptions for non-baffled culverts. In addition, the turbulent flow structure inside a full-scale culvert was compared to fish passage preferences.Velocity measurements were taken in a 1.83 m-diameter, 12.2 m-long corrugated metal culvert fitted with sloped- and slotted-weir baffles using a Sontek Micro-Acoustic Doppler Velocimeter for flow rates of 0.043, 0.085, 0.113, and 0.198 m3/s and a culvert slope of 1.14%. Results showed there were only minor differences in the turbulent flow structure created by each baffle type. The most significant differences included higher lateral turbulent intensities on the edges of the jet created by the slotted-weir baffles, and higher turbulent kinetic energies on the left side of the culvert (looking downstream) caused by the sloped-weir baffles. Downstream from a slotted-weir baffle, a reduced velocity and streamwise turbulent intensity zone was found near the left edge of the flow that was similar to that found in the bare culvert. The sloped-weir baffles produced a less pronounced zone near the right edge of the flow. No significant relationships could be found between the turbulence results of this study and biological fish passage tests performed at the same experimental site due to the lack of substantial differences in streamwise and lateral turbulence intensity distributions downstream from the tested baffles.