Numerical Study of Multiple Momentum Jets in a Vegetated Crossflow

Abstract

Vertically discharged multiple jets in crossflow is a common form of wastewater discharge. The presence of vegetation in the flow channel complicates the hydraulic characteristics of jets. The realizable k-ε turbulent model is used to simulate the flow, turbulence, and vortex characteristics of multiple jets with different spacing and jet-to-crossflow velocity ratios, to study the flow characteristics and vortex structure of multiple jets in a vegetated channel. The results reveal that vegetation inhibits the development of a counterrotating vortex pair. The jets with a low jet-to-crossflow velocity ratio are concentrated near the flow symmetry profile by the dual constraints of ambient flow and vegetation. The jets gradually spread outward and the counterrotating vortex pair become more obvious when the jet-to-crossflow velocity ratio increases. Vegetation reduces the shading effect of the front jet on the rear jet by accelerating the dissipation of shear layer vortices. The influence of the front jet on the rear jet decreases as the spacing increases.

Keywords

• vegetated channel
• multiple momentum jets
• numerical investigation
• turbulent characteristics
• vortex structure