  Mixing of reagents in microfluidics is necessary for various applications
however, due to the laminar nature of flows, efficient mixing in a small span
of length and time becomes difficult. The analysis of mixing of non-Newtonian
fluids is critical as they are commonly encountered in practical applications.
Towards this, we investigated an effective way for mixing of non-Newtonian
fluids using pulsatile velocity inlet conditions. In the present study, the
non-Newtonian fluid is modelled using the power law model with varying fluid
rheology from shear thickening to shear thinning. For enhancing the mixing,
pulsed velocity inlet condition is applied with varying phase angle and
frequency and compared with constant velocity inlet condition. We demonstrated
enhanced mixing using pulsing velocity inlet condition and achieved a maximum
mixing of 97.6% using pulsed input velocity with a phase difference of
180{\deg} and considering a frequency of 5 Hz for the case of shear-thinning
fluid (n=0.6). For the same condition, the mixing index is 89.1% and 85.2% for
Newtonian and shear thickening fluid (n=1.4), respectively. The present study
will be helpful in designing micromixers for mixing non-Newtonian fluid
effectively in a small span of length and time.
