Collective and individual oscillations of prominence threads excited by vortex shedding

Abstract We investigate transverse oscillations in solar prominence threads. Previous studies have proposed that such oscillations may be driven by vortex shedding. Although vortex shedding is well understood in hydrodynamics, its role under magnetohydrodynamic (MHD) conditions, such as those in the solar atmosphere, remains insufficiently explored. To better address this issue, we perform 3-dimensional MHD numerical simulations of prominence threads, modelled in 4 cases with 1, 2, 3, and 7 cylinders, anchored at their ends, i.e. line-tied, otherwise free to deform and oscillate at other parts, interacting with a plasma flow. These test studies enabled us to analyse both their oscillations and the associated flow patterns. We observe oscillatory motions with components both parallel and perpendicular to the plasma bulk motion, sometimes one-dimensional, and sometimes coupled. The associated periods differ between the components and depend on the configuration of the cylinders. Further, the oscillations of individual cylinders occur either in phase, in anti-phase, or with a time delay, depending on their configuration. In some cases, the perpendicular oscillations are caused by vortex shedding, and in some cases a Kármán vortex street is clearly observed.