Numerical reproduction of the spiral wave visualized experimentally in a wide-gap spherical Couette flow

SCF experiments were conducted according to the work of Egbers and Rath [Acta Mech. 111 pp. 125–140 (1995)]. Through visualization using aluminium flakes drifting on a horizontal plane illuminated by a laser sheet, the flow was identified as a spiral wave with azimuthal wavenumber $m=3$, using the experimentally obtained and numerically deduced comparison between phase velocities. By solving the equation of motion for the infinitesimal planar particles advecting in the flow field of the spiral wave, a visual distribution of reflected light was reproduced virtually, which is in good agreement with the picture obtained experimentally.