Experimental Investigations on Geometry Modulated Solute Mixing in Viscoelastic Media

In this study, geometrically modified microchannels fabricated using a stereolithography technique are employed to analyze micromixing of polymeric solutions. Experimental and numerical analyses were conducted to evaluate the qualitative and quantitative validity of the Newtonian fluid flow inside the geometrically modified channels. An in-house image processing code was used to analyze the dye concentration distributions resulting from complex fluid transport and mixing within the modified channels. Our analysis illustrates the existence of inertio-elastic instability in the geometrically modified microchannels for the transport of viscoelastic fluids. In addition, the presence of inertio-elastic instability significantly enhances the mixing efficiency as a result of the interaction between viscoelasticity and modified channel geometry. This analysis provides important physical insights into the cost-effective design and operation of microfluidic devices that handle viscoelastic fluids, which could be useful in designing and analyzing a passive micromixer that transports bio/polymeric fluids.