EXPERIMENTAL AND NUMERICAL ANALYSIS OF CHAOTIC ADVECTION AS AN EFFICIENT APPROACH TO MAXIMIZE HOMOGENEOUS LAMINAR MIXING IN A BATCH MIXER

Abstract In the present work, the impacts of effective parameters on the mixing of Stokes flows in a chaotic batch mixer are numerically and experimentally studied. The batch mixer consists of a container and two circular rotors where the rotors can rotate independently. To investigate the possibility of improving the mixing, the effect of non-constant speeds, contra-rotating rotors, and varying rotor speeds are studied. The results showed that varying the rotor speed while rotating in the same direction does not significantly increase mixing. However, if the rotors rotate in opposite directions, 10-times more mixing is achieved compared to the mode of rotating in the same direction. Nevertheless, given the constant speed of rotors, the flow is steady since the fluid particles have periodic movements in secondary flows, but the flow becomes chaotic and mixing is considerably increased by applying sinusoidal perturbations to the rotor speed. Nevertheless, for both modes of rotations in the same and opposite directions, the chaotic flow leads to increased mixing index in the same amount of time. Based on results, the best mixing results are achieved when the rotors rotate with sinusoidal rotational speed in opposite directions.