Rotating magnetic field driven spin-up flow in a rectangular cavity

Numerical simulations of the rotating magnetic field (RMF) driven liquid metal flow and corresponding velocity measurements using a dual plane, two-component ultrasound array Doppler velocimeter were carried out in a rectangular cavity with an aspect ratio of unity. The liquid metal (GaInSn) was suddenly exposed to an azimuthal body force generated by a RMF. The measurements show a similar flow structure compared to the case of the RMF-driven flow in a cylindrical container, in particular the so-called initial adjustment phase followed by an inertial phase which is dominated by inertial oscillations of the secondary flow. The transition from the double vortex structure of the secondary flow to an oscillating regime was detected at a magnetic Taylor number of Ta_cr > 1.3×10^5. A proper orthogonal decomposition (POD) of the velocity field allows a detailed study of the structure and time development of the most important flow modes.