A numerical investigation of a jet in an oscillating crossflow

Abstract

Numerical solutions are presented for a modified form of the canonical jet in crossflow (JICF) in which a steady round jet issues into a crossflow stream oscillating with a sinusoidal velocity profile. The numerical model uses large eddy simulation to simulate turbulent flow and mixing. This system is used to represent the dynamics and flow fields present during subsurface addition of reactants in stirred tanks. Thus, two variables associated with the oscillating crossflow velocity profile were manipulated to simulate the effects of impeller design and operation. Variation of the amplitude of crossflow oscillation had little effect on the trajectory of the jet plume, while variation in the frequency of crossflow oscillation was found to have a significant effect on plume trajectory. Additionally, oscillation of the crossflow affected the contiguity of the plume when compared with a steady crossflow JICF, resulting in mixing enhancement. The numerical solutions were validated using empirical data collected during a previous investigation of a steady crossflow JICF system. This research suggests that mixing during subsurface reagent addition could potentially be enhanced by optimizing impeller operating conditions and draft tube location, and the model presented here may offer a tractable computational method for optimization of these systems. © 2007 American Institute of Physics.