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Regular flow reversals in Rayleigh-Benard convection in a horizontal magnetic field
| Title: | Regular flow reversals in Rayleigh-Benard convection in a horizontal magnetic field |
| Authors: | Tasaka, Yuji Browse this author →KAKEN DB | | Igaki, Kazuto Browse this author | | Yanagisawa, Takatoshi Browse this author | | Vogt, Tobias Browse this author | | Zuerner, Till Browse this author | | Eckert, Sven Browse this author |
| Issue Date: | 8-Apr-2016 |
| Publisher: | American Physical Society (APS) |
| Journal Title: | Physical review e |
| Volume: | 93 |
| Issue: | 4 |
| Start Page: | 043109 |
| Publisher DOI: | 10.1103/PhysRevE.93.043109 |
| PMID: | 27176392 |
| Abstract: | Magnetohydrodynamic Rayleigh-Benard convection was studied experimentally using a liquid metal inside a box with a square horizontal cross section and aspect ratio of five. Systematic flow measurements were performed by means of ultrasonic velocity profiling that can capture time variations of instantaneous velocity profiles. Applying a horizontal magnetic field organizes the convective motion into a flow pattern of quasi-two-dimensional rolls arranged parallel to the magnetic field. The number of rolls has the tendency to decrease with increasing Rayleigh number Ra and to increase with increasing Chandrasekhar number Q. We explored convection regimes in a parameter range, at 2 x 10(3) < Q < 10(4) and 5 x 10(3) < Ra < 3 x 10(5), thus extending the regime diagram provided by Yanagisawa et al. [T. Yanagisawa et al., Phys. Rev. E 88, 063020 (2013)]. Three regimes were identified, of which the regime of regular flow reversals in which five rolls periodically change the direction of their circulation with gradual skew of the roll axes can be considered as the most remarkable one. The regime appears around a range of Ra/Q = 10, where irregular flow reversals were observed in Yanagisawa et al. We performed the proper orthogonal decomposition (POD) analysis on the spatiotemporal velocity distribution and detected that the regular flow reversals can be interpreted as a periodic emergence of a four-roll state in a dominant five-roll state. The POD analysis also provides the definition of the effective number of rolls as a more objective approach. |
| Rights: | ©2016 American Physical Society |
| Type: | article |
| URI: | http://hdl.handle.net/2115/61875 |
| Appears in Collections: | 工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 田坂 裕司
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