Numerical simulation of mixing two fluids of different viscosities in a microchannel with curved stirrer by LBM

In the present study, mixing of two fluids of different viscosities in a micro channel with an oscillating curved stirrer was simulated by MRT-LBM and the effect of geometric shape, oscillating speed and amplitude and viscosity logarithmic ratio on mixing efficiency was analyzed. Most researches in this field have studied the mixing of two same fluids but the mixing makes sense when two miscible fluids have different properties. Also in these researches, stirrers in micro channel are considered cylinder or rectangle shape. In this study, a curved stirrer was used for mixing two fluids of different viscosities in micro channel for the first time. The simulation was performed at Re=80 and Sc=10 and NASA/LANGLEY LS(1)-0417 (GA(W)-1) airfoil shape was used for curved stirrer. At the study of geometric shape, results showed that mixing efficiency of two fluids of same and different viscosities in micro channel with oscillating curved stirrer was higher than micro channel with oscillating rectangle stirrer. The results of stirrer oscillating amplitude and velocity survey revealed that increase in Strouhal number causes increase in mixing efficiency on studied oscillating amplitude and Optimum efficiency is on oscillating amplitude 0.5 on all studied Strouhal numbers. Also mixing efficiency decreases with increase of viscosity logarithmic ratio on studied Strouhal numbers and this decrease is noticeable in high Strouhal numbers.