  In this study, geometrically modified microchannels fabricated using
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 developed in
MATLAB 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 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 and could be useful in designing and analyzing a passive
micromixers that transport bio/polymeric fluids inside microchannels.

Fluid Dynamics;Soft Condensed Matter