Mixing of a continuous flow of two fluids due to unsteady flow

In many low-Reynolds number mixing applications, the absence of turbulence makes it difficult to achieve proper mixing of two fluids. In this paper, flow visualization is used to obtain quantitative measurements of mixing that occurs when combining two pulsatile fluid streams at a Y-connection. Mixing results from the interface distortion created by the pulsatile flow. This is generated by combining the action a peristaltic pump, which provides the mean flow, with the action of two pinch valves, one on each arm of the Y-connection, to generate strong pulsations. The action of the pinch valves is be controlled via pulse generators. Apparently chaotic conditions were realized in the confluence region, superimposed with the mean flow. The valve action was optimized to maximize mixing, the latter quantified via image analysis. This work demonstrates a low cost, efficient mixing device for low-Reynolds number conditions, which is therefore suitable for miniaturization.