Observation of Inertial Particle Motion in Laminar Flow in a Stirred Vessel

Abstract

Inertial particle motion in a stirred vessel with no baffle plate was observed experimentally and numerically at low Reynolds numbers. Several particles were captured on a torus orbit within one of the IMRs and kept traveling around the impeller. The particles captured in the IMRs enhance the exchange of material with the outside active mixing region. The primary and secondary circulation flow directions were defined φand θ-direction respectively. Initially, particle orbit obtained by Poincare section shows that the particle motion covers the full surface of the torus orbit and the ratio of the period for one round of a particle in φ-direction to that in θ-direction, Pθ /Pφ, is irrational, while after a long time, the circular orbit on the Poincare section converges on three discrete points and Pθ /Pφ is rational. Numerical simulation revealed that even after a particle seemed to have almost settled on a final orbit, the diameter of secondary circulation was not constant. After a particle has been captured, the drag force frequently works on the surface of the particle since the particle always exists near the impeller.