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.