Chaotic mixing and transport in wavy Taylor–Couette flow

Abstract

Chaotic transport and mixing in wavy cylindrical Couette flow has been studied in some detail, but previous studies have been limited to the velocity field at transition from Taylor–Couette flow to wavy flow or have used phenomenological, computational, or theoretical models of the flow. Recent particle image velocimetry measurements of wavy vortex flow provide the experimental three-dimensional, three-component velocity field at conditions well above the transition to wavy flow. Using this experimental velocity field, fluid tracer particles were tracked computationally to determine the nature of the mixing. The results show how mixing is enhanced with increasing rotating Reynolds number as a consequence of increased stretching and folding that occurs in meridional, latitudinal, and circumferential surfaces. The axial particle transport increases with the rotating Reynolds number as a consequence of stretching and folding within the vortices and the axial transport between vortices, both related to the waviness of the flow, as well as increased vortex strength. The calculated effective dispersion coefficient is very similar to that found experimentally and computationally confirming that chaotic advection is the mechanism responsible for enhanced mixing in wavy vortex flow.