Three-Dimensional Vortex-Induced Reaction Hot Spots at Flow Intersections.

We show the emergence of reaction hot spots induced by three-dimensional (3D) vortices with a simple A + B -> C reaction. We conduct microfluidics experiments to visualize the spatial map of the reaction rate with a chemiluminescence reaction and cross validate the results with direct numerical simulations. 3D vortices form at spiral-saddle-type stagnation points, and the 3D vortex flow topology is essential for initiating reaction hot spots. The effect of vortices on mixing and reaction becomes more vigorous for rough-walled channels, and our findings are valid over wide ranges of channel dimensions and Damkohler numbers.