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In this study, two phase gas-shear-thinning liquid flow in a square microchannel is numerically investigated using the coupled level set and volume of fluid (CLSVOF) methods. A systematic investigation is carried out to explore the influence of polyacrylamide (PAM) concentration, surface tension, velocity ratios, and contact angle on the gas slug length, volume, unit cell length, and pressure drop. Three different concentrations of PAM solutions, which exhibit shear-thinning behaviour are considered as the continuous phase. Gas slug length, volume, and unit cell length decreased with increasing the PAM concentration. Velocity and non-homogeneous viscosity distributions in the liquid slug for three different PAM concentration solutions are reported. Gas slug length decreases with an increase of the contact angle and the bubble shape change from convex to concave. This numerical work provides the fundamental insights in segmented flow formation and two-phase flow characteristics comprising shear-thinning liquids.

The influence of a curvature induced flow path in the form of a split and recombine microchannel is studied and compared with the output of a straight type micromixer. The mixing efficiency of ethanol into water is analyzed for diffusion dominated flows. Apart from parametric variations, the Dean flow analysis at different locations of the channels showed higher capability of the curvature induced geometries. The aspect of layer mixing is also examined by the strength of the expansion or contraction along the flow path, which signifies the effect of curvature upon the extent of mixing. Mixing efficiency as high as 94% has been achieved for the elliptical type of micromixer. Additionally, the influence of curvature toward the gradual increase and enhancement of mixing has been demonstrated with the gradual increase of the area of contact available in the split and recombine sections.