Study of micromixing systems employing extensional flows

Using computational fluid dynamics, the effect of implementing constrictions, defined by inverse functions, on the mixing performance of microfluidic devices operated in the laminar flow regime is investigated. The proposed designs combine uniform stretching flows generated by the hyperbolic constrictions with sheer flows resulting from the centripetal forces experienced by the fluids as they are directed along serpentine channels. Data showed that the mixing index is maximized for narrow and long constrictions. However, the required pressure differential for this global maximum in the mixing performance is also increased. Using in addition to the absolute mixing index measure, a cost of mixing measure as well, allows for a better optimization of the designs.