Intermittency in magnetohydrodynamic Taylor--Couette flow with the free-slip top and bottom walls

Y. Zhao¹ - J. Tao² - W. Hong¹ - R. Hollerbach³

¹ School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China
² Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China
³ School of Mathematics, University of Leeds, Leeds LS2 9JT, UK

Abstract
Turbulent Taylor-Couette flow with free-slip top and bottom walls under a purely azimuthal magnetic field is studied numerically by gradually increasing the Hartmann number. Different from the cases with periodic boundary conditions in the axial direction in our earlier work [1], irregular intermittency is found at moderate Hartmann numbers in our present work and the time-averaged azimuthal spectra of kinetic energy become higher and present a wave pattern at Ha = 68 and 72 compared to that at Ha = 60. Time series of kinetic energy and the γ-ratio of E_kθ=0 to the total kinetic energy of all the modes at Ha = 72.5 simultaneously demonstrate an abrupt sharp fall. At the same time, Joule dissipation has an abrupt sharp rise. At higher Hartmann numbers, the flow finally becomes purely two-dimensional and axisymmetric. Figs 6, Refs 28.