Modelling and numerical simulation of hydrodynamical processes in a confined rotating electrode configuration

This work presents an extensive hydrodynamic study of the rotating disk electrode in a confined electrochemical cell configuration. The deviation, particularly on the axis, with a classical Von Cochran expression is evaluated. The mathematical model of the hydrodynamic properties is presented and demonstrated. The numerical resolution of the equation system obtained is made using the Patankar finite volumes method using in the Fluent® code. The three stationary and transient velocity components of the flow, the gauge pressure and the stream function cartography have been calculated using nonstationary algorithms for rotation velocities ω∈{100;5×100;101;5×101;102} rad s−1 over the whole reactor volume. These results have been validated in the vicinity of the rotating disk by means of the classical analytical Cochran expressions. The results are in good agreement for large radial distances from the axis and for small axial distances from the electrode, which is important for electrochemical species fluxes, whereas an almost 40% difference has been calculated for the axial velocity profile component on the axis. This point is important because the first term of the truncated Cochran equation is widely used to estimate convective reactive species transport at the electrode surface. These expressions are good evaluations for peripheral profiles and there are few consequences for large surface electrodes. Validation “far from the electrode”, in the bulk has been made using LDA measurements. Good accordance between numerical and experimental data are obtained with problems arising at high rotation speeds. Very large turbulence intensities were measured at the chemical boundary layer frontier.