Experimental Investigations on the Effect of Axial Homogenous Magnetic Fields on Propagating Vortex Flow in the Taylor-Couette System.

Thomas Ilzig,Stefan Odenbach,Katharina Stöckel

doi:10.3390/ma12244027

Abstract

Experimental investigations of propagating vortex flow states (pV states) in a short Taylor–Couette system with asymmetric boundary conditions are presented. The flow state was established in a ferrofluid showing no magneto-viscous effect and was exposed to axial magnetic fields. It was found that the magnetic field led to a change in the spatial and temporal behavior of the pV state, indicating complex interactions between the flow field and magnetic field. A stepwise applied axial magnetic field destabilized the pV state, leading to an intermittent flow state. Gradually increasing the axial magnetic fields changed the temporal behavior of the regime. Up to magnetic field strengths of 20 kA/m, the orbital frequency, as a measure for the temporal periodicity, was increased with field strength.

Highlights

The Taylor–Couette system is a classical hydrodynamic model system, which has been in the focus of scientific interest for several decades
General of the the Investigated propagating vortex states (pV) State evaluating the basic structure of the pV regime and the transition region between the spiral vortex flows (SPI) and the pV state
In a direct comparison of both states we found that the phase propagation velocity of the SPIs was much higher than the vortex propagation velocity of the pV state, indicated by the inclination of the color-coded flow bands

Summary

Introduction

The Taylor–Couette system is a classical hydrodynamic model system, which has been in the focus of scientific interest for several decades now. Research has emphasized fundamental fluid dynamics, non-linear dynamics, self-organization and pattern formation etc., both experimentally and analytically [1,2,3,4,5,6,7]. Due to the fundamental mechanisms and principles, the effects known from the Taylor–Couette system are of substantial importance for the understanding of flow and heat transfer phenomena. The Taylor–Couette system benefits from a simple basic construction on the one hand and allows the investigation of various reliably reproducible flow states on the other. In its simplest form, the Taylor–Couette system consists of two coaxial cylinders of radii r1 and r2 and length L, which can rotate independently at angular velocities ω1 and ω2 , respectively (Figure 1). A viscous fluid of kinematic viscosity ν fills the gap of the width d = r1 − r2 between the two cylinders.

Methods

Discussion

Conclusion