Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system Journal Article

Author(s): Altmeyer, Sebastian; Do, Younghae; Lai, Ying-Cheng
Article Title: Magnetic field induced flow pattern reversal in a ferrofluidic Taylor-Couette system
Affiliation IST Austria
Abstract: We investigate the dynamics of ferrofluidic wavy vortex flows in the counter-rotating Taylor-Couette system, with a focus on wavy flows with a mixture of the dominant azimuthal modes. Without external magnetic field flows are stable and pro-grade with respect to the rotation of the inner cylinder. More complex behaviors can arise when an axial or a transverse magnetic field is applied. Depending on the direction and strength of the field, multi-stable wavy states and bifurcations can occur. We uncover the phenomenon of flow pattern reversal as the strength of the magnetic field is increased through a critical value. In between the regimes of pro-grade and retrograde flow rotations, standing waves with zero angular velocities can emerge. A striking finding is that, under a transverse magnetic field, a second reversal in the flow pattern direction can occur, where the flow pattern evolves into pro-grade rotation again from a retrograde state. Flow reversal is relevant to intriguing phenomena in nature such as geomagnetic reversal. Our results suggest that, in ferrofluids, flow pattern reversal can be induced by varying a magnetic field in a controlled manner, which can be realized in laboratory experiments with potential applications in the development of modern fluid devices.
Journal Title: Scientific Reports
Volume: 5
ISSN: 20452322
Publisher: Nature Publishing Group  
Date Published: 2015-12-11
Start Page: Article number: 18589
Copyright Statement: CC BY
DOI: 10.1038/srep18589
Notes: Y.D. was supported by Basic Science Research Program of the Ministry of Education, Science and Technology under Grant No. NRF-2013R1A1A2010067. Y.C.L. was supported by AFOSR under Grant No. FA9550-15-1-0151.
Open access: yes (OA journal)