End-wall effects on the transition between Taylor vortices and spiral vortices

TL;DR

This study investigates how rigid end-walls influence the transition between Taylor vortices and spiral vortices in the Taylor-Couette system, revealing new bifurcation structures and flow behaviors through simulations and experiments.

Contribution

It provides the first detailed analysis of end-wall effects on vortex transitions, introducing stable wavy spiral structures and characterizing their bifurcations in the system.

Findings

Pure spiral solutions are replaced by stable wavy spirals with rigid end-walls.

Transitions involve wavy Taylor vortices and propagating defects.

Bifurcation of wavy spirals from Ekman flow was observed.

Abstract

We present numerical simulations as well as experimental results concerning transitions between Taylor vortices and spiral vortices in the Taylor-Couette system with rigid, non-rotating end-walls in axial direction. As in the axial periodic case, these transitions are performed by wavy structures appearing via a secondary bifurcation out of Taylor vortices and spirals, respectively. But in the presence of rigid lids, pure spiral solutions do not occur but are substituted by primary bifurcating, stable wavy spiral structures (wSPI). Similarly to the periodic system, we found a transition from Taylor vortices to wSPI mediated by so called wavy Taylor vortices (wTVF) and, on the other hand, a transition from wSPI to TVF triggered by a propagating defect. We furthermore observed and investigated the primary bifurcation of wSPI out of basic Ekman flow.