chapter  15
14 Pages

Multiple jet interaction in stagnant shallow water

ByA.C.H. Lai and J.H.W. Lee

ABSTRACT: Multiple shallow water jets discharged from a unidirectional multiport diffuser can be found in a number of environmental hydraulics problems such as thermal discharges from once-through cooling water systems or pollutant discharges in a river. Previous studies have shown that dynamic interaction is significant for such jet groups which act like a line momentum source or two-dimensional actuator disk. Traditional integral jet models for a single free jet are not applicable for predicting the mixing of such jet groups. In this paper, a recently proposed semi-analytical model to predict dynamic jet interaction is applied to the problem of multiple shallow water jet discharges in stagnant ambient. The flow field induced by jets is computed by a distribution of point sinks of strength equal to the entrainment per unit length along the jet trajectory and accounting for boundary effects. The jet flow is determined by an iterative solution of an integral jet model accounting for dynamic pressure and momentum flux changes. Model predictions are in good agreement with experimental data for several key jet group mixing characteristics.