Multi-scale analysis of hydrodynamics inside a network of crossing minichannels using electrodiffusion method and PIV measurements

Abstract

Knowledge of local hydrodynamics inside miniaturized systems is necessary for industrial applications. In this work two techniques are used in order to characterize the flow in a network of crossing minichannels. These techniques are respectively based on the particle image velocimetry and on electrochemical microsensors used in the local diagnostic of the flow in order to set-up multi-scale analysis of the hydrodynamics inside a tested system. PIV measurements are applied in front of electrochemical sensors in order to obtain mean velocity fields along the cell. The comparison of velocity profiles with that obtained in fully developed channel flow emphasize the developing behaviour of the flow between two successive crossings. Vortices in the near wall region have been detected using the electrochemical technique at different positions corresponding to the location of the electrodes. The calculation of statistic parameters such as flatness and skewness factors of the instantaneous values of wall shear rate shows that the flow exhibits an intermittent regime behaviour. Finally, a multi-scale hydrodynamics pattern is proposed to describe the turbulence properties in the near wall region at the crossing of two channels.