Flow visualisation: a voltammetric approach

A novel approach to the visualisation and quantification of mass transfer in liquid flow is presented. The technique utilises an array of microstrip electrodes sited within a duct through which the electrolyte solution is pumped. The electrolyte solution contains a reagent that may be oxidised and in the process undergo a colour change. The electrolysis products are then swept through the cell and the pathway imaged via a digital video. Results are presented for an experimental geometry where a rectangular obstruction is deliberately introduced into the duct. Transport rates within the cell are restricted such that Stokes flow conditions are maintained throughout and the streamlines generated from the electrolysis used to map the flow profiles through the devices. The merits of the approach are discussed and the potential of numerical modelling to provide quantitative analysis are highlighted.