Mixing of miscible shear-thinning fluids in a lid-driven cavity

The concentration and velocity fields of two refractive index matched miscible shear-thinning fluids in a lid-driven cavity were investigated by using planar laser-induced fluorescence and particle image velocimetry, as well by computational fluid dynamics. Quantitative analyses show that the results obtained by flow simulations with the species transport model are in good agreement with the experimental results. The effects of different parameters were studied by using the intensity of segregation. For two fluids with the same rheological parameters, the relative amounts of liquids H1/H and the power-law index n dominate the mixing process while the Reynolds number Re plays a marginal role. As for two fluids with density difference, buoyancy has significant influence on the mixing process. The dimensionless group (redefined such as to include shear thinning behavior) is proposed for assessing the effect of buoyancy and rheological properties on the mixing of miscible shear-thinning fluids.