Nonaxisymmetric modes of magnetorotational and possible hydrodynamical instabilities in the upcoming DRESDYN-MRI experiments: Linear and nonlinear dynamics

Magnetorotational instability (MRI) is responsible for angular momentum transport in astrophysical disks. However, its definitive experimental confirmation is still missing. The upcoming DRESDYN-MRI experiments using a liquid sodium Taylor-Couette flow are a new effort to detect MRI. In preparation for this, here we study the dynamics of nonaxisymmetric MRI via simulations for the DRESDYN-MRI device. It is shown that nonaxisymmetric modes are important for large R00exe4×10⁴ and relevant in these experiments with R00exe10⁶. These modes are, however, of nonmagnetic nature, which grow and form a turbulent boundary layer near the cylinders, while axisymmetric MRI dominates in the bulk flow.