Inertial Microfluidics: Flow instabilities and mixing in 2-dimensional cross slot

GOMBA, J. M.; UBAL S.; HULIN J. P.; CORREA, P. G.; AURADOU H.

Córdoba

Congreso; II Brazil-Argentine Microfluidics Congress. V Congreso de Microfluídica Argentina; 2019

The conventional flows in microfluidic technology usually remain in the Stokesregime, this is low Reynolds number, Re 65 a second flow regime wasfound, characterized by a time-dependent behavior in both outlet branches. Whilefor A = 1 the liquid from each inlet flows stationary and separates in equal parts at each of the two outlets, for A = 3 the liquids from each inlet discharge into different outlets. This last situation is not stationary, since the discharges alternate towards one or the other output with a well defined frequency. The oscillatory flow creates and destroys multiples recirculation bubbles attached along the outlet walls. We identified the frequency of the flow and its dependence on Re. The diffusion-convection equations were added into the model to determine the mixing properties for the different flow states. We quantified the mixing performance by evaluating the intensity of segregation. While for the symmetric and the asymmetric flow states the mixing only takes place by diffusion along the sharp interface of the two fluids, the oscillatory state improves the mixing, particularly, in the recirculation zones.