Jason Picardo (Univ. Florida/Indian Institute of Technology, Madras) - Centrifugal instability and vortices in layered flow through curved microchannels

In this talk, I shall discuss the influence of centrifugal forces on layered flow of two viscous immiscible fluids in curved channels. The first half of the talk will focus on flow in a semi-infinite channel formed by the annular gap between concentric cylinders. Here the steady base flow, which is purely azimuthal, bifurcates to a three-dimensional flow with toroidal vortices as the flow rates are increased. At the onset of this centrifugal instability, a variety of stationary and travelling vortex patterns can arise due to viscous interaction between the fluids. The second half of the talk will consider the bounded case of a curved channel with a square cross- section. Here a unidirectional flow is impossible; instead secondary dean vortices are formed within each fluid. Again, viscous coupling between the fluids results in a variety of circulatory flow patterns, which in turn impact the shape of the interface and the flow rates of the fluids. This work has implications for the enhancement of inter-fluid mass transfer in curved microchannels for applications such as microscale solvent extraction and interphase reactions.