3D Nonaxisymmetric Simulations of the free Stewartson-Shercliff Layer with Insulating and Conducting Axial Boundaries

Results are presented from 3-D numerical nonaxisymmetric simulations of the Princeton MRI Experiment, which is a modified Taylor-Couette device with GaInSn as its working fluid to study rotational MHD flows. Spectral Finite Element Maxwell and Navier Stokes (SFEMaNS) code is utilized to investigate the effect of axial boundary conductivity on a free Stewartson-Shercliff Layer (SSL). The free SSL is established by a sufficiently strong magnetic field imposed axially across the differentially rotating fluid with two rotating rings enforcing the boundary conditions. Numerical simulations show that the response of the bulk fluid flow is vastly different in the two different cases of insulating and conducting endcaps. We find that for the insulating endcaps, there is a transition from stability to instability of a Kelvin Helmholtz-like mode that saturates at an azimuthal modenumber m = 1 and at an Elsasser number for GaInSn of unity, while for the conducting endcaps, the reinforced coupling between the magnetic field and the bulk fluid generates a strong shear in the azimuthal velocity resulting in Rayleigh-like modes even at reduced thresholds for the axial magnetic field. Numerical results will further be compared with the experimental measurements [K. Caspary et al. PRE 2018].