An Evaluation of Fluid Flow Interference in Type 1 Parallel Pipe Culverts

The present study considers the potential for interference in type 1 parallel pipe culvert systems. Interference is the reduction in capacity of a parallel culvert system, relative to a single culvert system, due to additional energy losses associated with secondary flows developing in the parallel system. The present study analyzes the culvert systems using the standard free surface flow solver provided in the OpenFOAM software package. The free surface flow solver is a three-dimensional numerical model, based on the Reynolds averaged Navier-Stokes equations, the standard k-epsilon model, and approximates the free surface using a volume averaged method. The potential for interference was evaluated by using the solver to determine the headwater depth for both single and parallel culvert systems. The culvert headwater depth predicted by the solver for the single culvert system compares favorably with corresponding results determined using traditional one-dimensional hydraulics. The study also found that the capacity of the parallel culvert system was equal to twice the capacity single culvert system. However, the solver incorrectly predicted maximum values for the turbulent kinetic energy and eddy viscosity.