Eulerian chaos in NETmix: strange attractors and Poincaré analysis

Abstract

NETmix is a static mixer formed of chambers interconnected by channels. Under laminar chaotic conditions, the oscillating behaviour in the chambers promotes enhanced mixing from the onset of chaotic features, which are sensitive to parameters changes. This work studies the influence of the chamber diameter to channel width ratio, identifying the range, 6.65 < D/d < 6.85, for nearly perfect mixing. The chaotic behaviour of NETmix is analysed through the characterization of its strange attractors and their relationship with the reactor performance; a thin W shaped strange attractor is present when nearly perfect mixing occurs. Poincaré maps are used to capture the quasi-periodic nature of NETmix, leading to D/d = 6.65 as the ratio for optimal mixing conditions. At this ratio, the Poincaré map exhibits a well-defined spinning spiral structure which holds its shape as the Poincaré section changes, indicative of a stable quasi-periodic regime.