Experimental and computational comparison of baffled-culvert hydrodynamics for fish passage

Abstract

For some applications, fish passage through culverts may be enhanced by adding weir baffles along the culvert invert. In an effort to evaluate the effectiveness of computation techniques as a design tool for baffled-culvert design, turbulent free-surface flow conditions through a weir-baffled-lined culvert were simulated numerically using a three-dimensional numerical model utilizing three different turbulence models: k–, renormalized group k–, and large Eddy simulation. Experimental data from a small prototype-scale baffled-lined culvert, measured using particle image velocimetry, were used to assess the ability of these turbulence models to predict the turbulent flow characteristics for various culvert slopes and discharges. All computer simulations struggled in the regions of high shear and reverse flow, independent of the specific turbulence model used. Comparisons between the measured and computed flow field velocity and turbulent kinetic energy data, however, found that the renormalized group k– model provided the best approximation of the flow field, which included undulating supercritical flow profiles with recirculating eddies downstream of each baffle. Despite the limitations found in this study, computational fluid flow modeling represents a reasonable design tool-baffled-culvert design.