Optical Diagnostics
MTFL has developed and integrated a novel droplet dynamics measurement technique that employs a single fluorophore laser-induced
fluorescence, custom image processing, and statistical analysis for determining droplet volume, translation velocity, and frequency
as well as monitoring and quantifying mixing in confined, high speed droplet collisions. The diagnostic procedure captures time
varying fluorescent signals following binary droplet collisions and reconstructs the spatial concentration field by relating fluorophore
intensity to relative concentration. Mixing information is revealed through two governing statistics that separate the roles of convective
rearrangement and molecular diffusion during the mixing process. The end result is a viewing window into the rich dynamics of droplet
collisions and a diagnostic tool that differentiates between poor and effective mixing. The technique has proved invaluable in the
laboratory by allowing direct comparison of different hydrodynamic conditions, such as collision Reynolds and Peclet number, and
collision geometries, such as T and Y-junctions.