Three-dimensional numerical simulation of MHD turbulent shear flows*

Flow of an electrically conducting fluid in a cylindric container is analysed with direct numerical simulations (DNS). The flow geometry and the value of the injected current density(I) or magnetic fields(B) are corresponding to the experiment of Messadek(2002) . In this work, the cases with injected radius r_e=0.054m  and 1T≤B ≤3T, 3A≤ I ≤20A have been selected to investigate, in which parameter space turbulence regime is  well-established, whereas Hartmann layers remain laminar. Via a visualization way, we find that the flow experiences a complex evolution and the tendency of large structures variation with the increasing of I and B. The mean velocity profiles exhibit that the thickness of free shear layer is increased by the turbulence. For the present parameter space, the angular momentum of the numerics agrees well with that of the experiments and theoretical solutions. DNS shows that the energy spectra exhibits a power law close to k^-5/3 when the Joule dissipation is weak and close to k^-3 when it is significant, which appears consistent with the theory and the experimental results of Messadek(2002).