Influence of imposed oscillatory frequency on mass transfer enhancement ofgrooved channels for pulsatile flow

The present experimental study describes mass transfer enhancement in groov ed channels with different cavity lengths for pulsatile flow. Overall and l ocal mass transfer rates were measured by the electrochemical method with a high Schmidt number and also the vortical motion within the groove was vis ualized by the electrolytic precipitation method. We especially focused on the influence of oscillation frequency on mass transport enhancement. Trans port enhancement by means of fluid oscillation is found to be higher in lam inar flow than in turbulent flow. There is a noticeable enhancement at inte rmediate Strouhal numbers, depending on the cavity length and the net flow Reynolds number. It is revealed that the mechanism for a peak transport enh ancement factor against Strouhal number is not explained by the hydrodynami c resonance proposed by Patera and Mikic, under a certain condition. (C) 20 00 Elsevier Science Ltd. All right reserved.