Abstract
Development of magnetohydrodynamic (MHD) convection during copper magnetoelectrolysis between two vertical electrodes under galvanostatic conditions was studied. An unsteady two-dimensional CFD simulation under a linear external magnetic field was performed. The governing equations with inclusion of Lorentz and buoyancy forces were solved. For pressure-velocity coupling and pressure interpolation, the SIMPLE algorithm and the second order scheme were used, respectively, and the first order implicit temporal discretization was used using a pressure-based CFD solver. CFD results were investigated in two orientations of the Lorentz force relative to the buoyancy force, parallel and antiparallel. The obtained results on velocity and concentration profiles in a parallel case showed a good agreement with the experimental data and results of a recent simulation by the finite element method. Moreover, a similar trend was observed between the results of the antiparallel case and experimental data. The results showed that circular MHD convection between electrodes has a complex interaction with the buoyancy force and this interaction leads to velocity decay. The maximum vertical velocity component at mid-height of the cell for pure natural convection electrolysis is 0.3 mm/s, which is about 18 and 21% of its value in parallel and antiparallel cases, respectively. Moreover, its reduction at the second stage of the antiparallel case was about 90%, which is much more than 33% in the parallel case and 21% in the pure natural convection case. The competition between the Lorentz force and the buoyancy force is also discussed. Key words: CFD, magnetoelectrolysis, Lorentz force, MHD convection, natural convection, concentration stratification. Tables 1, Figs 23, Refs 26.