AM06-03-023 磁場下導電性流れ中の渦の減衰率(乱流渦構造(5),一般講演)

概要

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The damping rate of vortices in an electrically conducting fluid submitted to a uniform magnetic field is analyzed for large Hartmann number Ha. The fluid is contained in a layer of constant thickness h, bounded by two insulating walls that are perpendicular to the magnetic field. The damping times and the eigenfunctions along the magnetic field are obtained from a linear eigenvalue problem. According to the damping times and these eigenfunctions, vortices are classified into several classes by the range of combinations of the mode number m in the magnetic field direction and the wavenumber k_<2D>, in the plane perpendicular to the magnetic field. Namely, it is found that the damping rate of vortices in the range of k_<2D>〜{(m+1/2)πHa}^<1/2>h^<-1> and m=0, 1, 2 is of the same order as that of large-scale two-dimensional vortices. This fact suggests that actual quasi-two-dimensional MHD turbulent flows include not only m=0 but also higher mode (m≥1) eigenfunctions of this wavenumber range, although the eigenfunction of m=0 has a 30% variation and the higher mode eigenfunctions change their sign along the magnetic field.
日本流体力学会の論文
2006-09-05