Junction contraction for a T-shaped micro-channel to enhance mixing

A design concept of a junction contraction is proposed for a T-shaped microchannel to enhance mixing. The proposed design entails contracting the flow passage at the junction of two fluids in a T-shaped microchannel. It is validated numerically by application to a well known T-shaped microchannel. The proposed junction contraction results in a noticeable improvement in mixing. The improvement of mixing is found to be caused by a vortex flow around the junction contraction. A downward flow is shown to form just before the contraction and is followed by an upward flow. The dependence on the position and the size of contraction is also studied. The best degree of mixing is obtained when the contraction is placed in the range of 50–125 μm downstream the junction of the two fluids being mixed. The mixing enhancement is found to increase quadratically with the contraction ratio. However, more contracted junction requires a larger pressure drop.