A pair of adjacent bubbles evolution at micro-electrode under electrode-normal magnetic field

This work investigates the effect of Lorentz force on the growth, coalescence and detachment of a pair of adjacent hydrogen bubbles. The bubbles are electrolytically generated from two horizontal micropores (d = 0.2 mm) with 1 mm between each other which is processed by the printed circuit board technology. The experiment is conducted in the acidic environment (0.5 mol/L H2SO4) with an electrode-normal homogeneous magnetic field (0.9 T) superimposed. The Lorentz force induced by the current distortion around the growing bubble and the rim of micro-electrode brings the so-called micro-magneto hydrodynamic (MMHD) convection in the scale of bubble size. The experiment gave the visualization research of bubble evolution, and it showed that MMHD convection delayed the adjacent bubble coalescence and decreased the bubble growth rate. Based on the computational fluid dynamics (CFD), the MMHD convection around the pair of bubbles is present clearly. It is found that pair of relative lower pressure areas is formed on the outside of pair of bubbles, and the pressure difference makes the bubble coalescence difficult. (C) 2020 Elsevier B.V. All rights reserved.