Refractive-index-matched polymer for experimental fluid dynamics in water

In experimental fluid dynamics, it would be invaluable to have solids with a refractive index similar to that of water, hence simplifying the use of existing facilities to study flows around complex geometries. Here we report a polymer that is refractive-index-matched with water at room temperature and can be cast in thick specimens. We successfully demonstrated its use with three common laser-based diagnostics: laser-induced fluorescence, particle image velocimetry, and molecular tagging velocimetry.