Three-dimensional numerical study on hydrogen bubble growth at electrode

Three-dimensional direct numerical simulation of electrolysis is applied to investigate the growth and detachment of bubbles at electrodes. The moving gas-liquid interface is modeled employing the VOF-based method. To reduce computational cost, a reduced surface tension is employed, and a sensitivity study has been performed to ensure the accuracy of the simulations. The simulations include the growth phase of the bubbles, followed by their detachment from the electrode surface, and the results are validated with analytical models and experimental data. The bubble growth is diffusion-controlled, leading to the scaling R ∝ t 1 / 2 . However, during the early stage, the growth exponent deviates from 1 / 2 , exhibiting either super- or sub- 1 / 2 behavior depending on the initial boundary conditions. We further demonstrate that the number of nucleation sites significantly affects gas transport, as quantified by the Sherwood number. The influences of contact angle and nucleation site on bubble detachment are also examined. The predicted detachment radius varies linearly with contact angle, consistent with Fritz’s linear relation between the volume-equivalent radius and contact angle, confirming that the surface tension is the dominant attachment force. Finally, as the nucleation sites increase, the induced bubble coalescence accelerates the bubble detachment. Taken together, these findings give us valuable insights into improving gas bubble removal and enhancing overall electrolysis efficiency. • Performed three-dimensional Direct Numerical Simulations (DNS) coupled with a Volume-of-Fluid (VOF) method to accurately capture the dynamics of deformable gas–liquid interfaces. • Quantitatively demonstrated the significant effects of contact angle and the number of nucleation site on the hydrogen mass transfer rate. • Investigated the role of bubble–bubble coalescence dynamics in determining the final bubble detachment size and the associated detachment time.