Numerical Investigation of Circular Turbulent Jets in Shallow Water

Abstract

Knowledge of turbulent jets in shallow water depths is of utmost importance to adequately characterize municipal and industrial discharges. Propagation and dilution of such discharges are influenced by the presence of channel bed and water surface at close proximity. This study numerically investigates the bed/water surface confinement effects on circular turbulent jets by analyzing key parameters such as decay of maximum velocity, velocity profiles, growth of jet, locus of maximum velocity, and turbulence properties. Results reveal that the confinement has a profound impact on the entrainment and mixing characteristics of a jet. Entrainment is suppressed at the confining surface, and as a consequence velocity decays at a lower rate. The locus of maximum velocity shifts toward the closest confining surface for asymmetrical cases, whereas it shifts toward the bed for symmetrical cases. Mixing of a jet both in the horizontal and the vertical planes is affected significantly by the confinement. Turbulence characteristics differ significantly in the vertical plane only. Findings from this study will be useful for characterizing properties of circular jets discharging in a confined ambient conditions.