Mean and unsteady hydrodynamic and mass transport properties at a rotating cylinder electrode: from laminar to transitional flow regime

The rotating cylinder electrode configuration (RCE) is one of the most used electrochemical configurations. It is mostly used for the study of turbulent regimes and also for laminar regimes. However, it is difficult to choose an accurate and predictive correlation for the limiting current, even for laminar regimes. Published literature exhibit mean Sherwood number defined with different hydrodynamic dimensionless numbers (Reynolds or Taylor), different characteristic lengths, different electro-active lengths or different electrode position. The electrode length is a particularly important factor. This is the reason why rigorous two-dimensional calculations of the RCE configuration are very adapted. Computational fluid dynamic tools, like Fluent® software, appear to offer a good strategy to address the electrochemical properties at electrode vicinity. This has been done in this work for Reynolds number in the interval [70; 280] or Taylors number in the interval [440; 1740]. A complete design experiment strategy has been used to correlate fluid flow properties with classical factors like viscosity, rotation velocity and inner electrode diameter, and also with the axial position along the inner rotating electrode. The properties of sensitivity with experimental conditions like no slip free surface or steady flow regime have also been investigated. In this configuration, numerical results show hydrodynamic unsteady properties approaching the end of the laminar regime. Finally, with the flow knowledge, a numerical strategy to estimate the local current density is proposed using Lévêque theory