Turbulence Characterization in a Gully with Reverse Flow

This work presents an experimental investigation on turbulent flow characteristics in a typical gully with reverse flow. Four different flow rates (the inlet Reynolds number ranged between and ) were characterized in a laboratory facility using an acoustic Doppler velocimeter. A complete signal analysis was carried out to identify and remove the influence of errors in acoustic Doppler measurements on the computation of the mean velocity, turbulent kinetic energy, and Reynolds stresses. The flow showed a similar pattern between the different analyzed experimental conditions in terms of mean velocity and turbulent kinetic energy. A macroanticlockwise spanwise axis vortex was identified based on the mean velocity field in the region encompassed between the upstream wall and the inlet centerline. Maximum mean velocity magnitudes were approximately 25% of the inlet velocity and characterized the outer flow of the vortex. Higher turbulent kinetic energies were observed at the inlet centerline region with values approximately 5% of the inlet velocity square. The Reynolds stresses exhibited some anisotropy, which was revealed by both the shear stresses values and by the differences in the normal stresses. Normal stresses were higher than shear stresses, with maximum values at the inlet centerline region (about 3%, 5% and 2% of the inlet velocity square in the streamwise, spanwise and vertical direction, respectively). (C) 2013 American Society of Civil Engineers.