Three-Dimensional Numerical Study of Multiple Vertical Buoyant Jets in Stationary Ambient Water

In this paper, the mixing and dilution characteristics of vertical buoyant jets discharged from multiport diffusers are studied numerically. The performances of four different turbulence closures are investigated, including the standard k-epsilon, renormalization group (RNG) k-epsilon, standard k-omega, and k-omega shear stress transport (SST) models, and the simulated results are compared to available experimental measurements. The comparisons demonstrate that a fully three-dimensional (3D) numerical model can be a reliable tool for the study of multiple vertical buoyant jets. Different fit measurement methods are employed to evaluate the turbulence models, and the results show that the predictions by the RNG k-epsilon model are the most accurate. The validated model is utilized to carry out additional computations with different port spacings and densimetric Froude numbers (Fr), and the simulated centerline and transverse concentrations at various cross sections are extracted and analyzed. The study reveals how varying port spacing and Fr affect multiple vertical buoyant jets. A new empirical formula that considers the port-spacing effect is proposed to describe the concentration decay along the jet centerline. The study also provides clues about merging points, well-mixed locations, and jet spread under the influences of port spacing.