Experiments and numerical simulations of vortex ring formation in microgeometries

The study is focused on the investigation and modeling ofthe vortex ring formation in two micro-configurations: (i)the starting of micro-jet-formation in a fluid domain at rest (as benchmark test), and (ii) the evolution of post focusing vortical structures developed in a cross-shaped micro-junctions. The paper describes the experimental set-ups and presents the direct visualizations of the flow patterns. The phenomena are analyzed by comparing the experiments with the numerical simulations performed by the FLUENT code. The numerical results are found consistent with the experimental observations and confirm the value of CFD procedure in developing novellab-on-a-chip applications.