Flow Physics and Enhanced Mixing in Confined Impinging Jet Mixers

Confined Impinging Jet Mixers (CIJMs) are used in chemical processes that requires fast mixing. In this mixing device, two jets from opposite sides, directly impinge on each other, form thin shear layers. These shear layers rapidly break down into small structures, and this enables effective mixing of the species transported by each jet. Interaction of the shear layers with the inner walls can induce self-sustained oscillation of the shear layers, and this can significantly enhance the mixing process. In the present study, we investigate the flow physics, especially the instability and self-sustained oscillation of the impinging jet shear layers. The study employs direct numerical simulation with a sharp interface immersed boundary method (ViCar3D). To better understand the instability of the confined impinging jet, we compare the behavior of confined and unconfined impinging jets.