Abstract
Experiments on the mixing of two different fluids at low Reynolds number inside helical channels have shown that their curvature and torsion induce secondary flow at the channel cross section, which enhances mixing between liquids. While these channels are mostly of symmetric cross section, e.g., circular and rectangular, recent experiments suggest that helical channels with asymmetric cross sections can enhance mixing even further. There have, however, been few systematic studies on the coupled effect of the asymmetry of a channel cross section and its three-dimensional orientation on the mixing of fluid streams. In this regard, we have examined mixing between three differently dyed streams of cross-linkable silicone material inside triple-helical microchannels; we have also simulated the flow of liquids through such channels using fluent software. Our results show that the length of the interface that separates different liquids at any cross section varies linearly with a nondimensional parameter involving curvature, torsion, axial length, and helix radius of the channel. Moreover, mixing efficiency increases with Péclet number, the exponent of variation being dependent on the Reynolds number of flow.
6 More- Received 12 July 2019
- Accepted 21 May 2020
DOI:https://doi.org/10.1103/PhysRevFluids.5.064502
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