Flows Characteristics of Two Immiscible Swirling Fluids in a Cylinder

Abstract

Flows of an oil-glycerin system of immiscible Newtonian fluids, driven by the independent rotation of the boundaries of a vertical cylinder with axial rod are investigated numerically. Moderate lid rotation rates are shown to generate breakdown in the adjacent oil phase, associated to significant interface displacement and flow reversal. The vortex pattern and interface behavior are found to be very sensitive to the distinct and combined effects of fluids volume fraction and background rotation. In particular, a decrease of the oil phase volume causes bubble expansion and evolution into a ring type vortex prior to its suppression as it coalesces onto a convex shaped interface. In addition, the vortex structure may efficiently be prevented (enhanced) by means of low rates of sidewall counter-rotation (co-rotation). Moreover, addition of swirl by means of the central rod rotation is found to have a considerable impact on the lid driven vortex flows characteristics in qualitative accord with prior experiments.

Keywords: immiscible fluids, cylinder, central rod, rotating walls, breakdown, interface behaviour.