Direct numerical simulation of near-wall turbulent flow and ionic mass transport in electrochemical reactors using a hybrid finite element/spectral method

An experimental study and direct numerical simulation of near-wall turbulent flow and ionic mass transport was performed in a cylindrical electrochemical reactor for Reynolds numbers up to 18,000 (friction Reynolds number of 1245). The experimental part involved the determination of velocity gradients close to the wall of a rotating cylinder. These velocity gradients are determined by electrochemical mass transport measurements to a rotating cylinder electrode and to micro-electrodes embedded in a rotating cylinder. Simulation of the fluid flow with passive scalar is accomplished using a hybrid finite element method (FEM) in meridian planes coupled to a Fourier expansion in the azimuthal direction. It was shown that the method reproduces the turbulent flow statistics with high accuracy. Due to its high parallel efficiency and the possibility of stretched meshes in finite element planes near the wall, this hybrid method is suitable to study laboratory electrochemical systems. Coupling with mass and energy transport equations allows prediction of the concentration and temperature fields. This feature makes the model suitable for large-scale design and optimization of different electrochemical processes where accurate prediction of near-wall turbulence and ionic mass transport is required.