抄録
The present experimental study describes mass transfer enhancement in grooved channels with different cavity length under low Reynolds number pulsatile flow condition. Overall and local transport enhancement characteristics were measured by the electrochemical method at high Schmidt number. The vortical motion within the groove was visualized by the electrolytic precipitation method. Experiments were carried out under a fixed Reynolds number for the steady component, Res =56, and we focused attention on the effect of parameters of oscillation.
In contrast to the results at moderate Reynolds numbers, the overall transport enhancement factor depends on the oscillatory fraction of the flow rate, but it is insensible to the Strouhal number. Furthermore, this factor is found to increase as the cavity length of grooved channel increases. The effect of the oscillatory fraction on the local transport enhancement factor is sensible to the position along the bottom of groove. The maximum of the local enhancement factor occurs in the upstream side rather than in the downstream side in the groove. The results of flow visualization revealed the existence of a direct ejection of fluid element from the groove part towards the channel part under pulsatile flow, which gives transport enhancement.
