Instability of electrolyte flow driven by an azimuthal Lorentz force

J. Pérez-Barrera¹ - J. E. Pérez-Espinoza¹ - A. Ortiz^{1, 2} - E. Ramos¹ - S. Cuevas¹

¹ Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Temixco, Morelos, 62580 MEXICO
² Universidad Autónoma de Baja California, Blvd. Benito Juárez S/N. Unidad Universitaria, Mexicali, B.C. 21280 MEXICO

Abstract
We describe of an instability in a free surface flow produced by an azimuthal Lorentz force in a layer of an electrolyte contained in an open electromagnetic stirrer with cylindrical geometry. The force is created by the interaction of an applied radial electric current within the range 25--400 mA and an approximately constant magnetic field (0.04 T) parallel to the cylinder's axis. The flow instability leads to the formation of cyclonic vortices close to the internal electrode and anticyclonic vortices close to the external electrode, in the plane normal to the magnetic field. Flow visualization using dye reveals that the travelling anticyclonic vortices remain for long times once they appear. Detailed flow patterns are explored through Particle Image Velocimetry measurements with the aim of clarifying the mechanisms that originate the vortex formation. Tables 1, Figs 8, Refs 15.