Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 52 11 2019 10 08 Numerical Simulation of Mixing Two Fluids of Different Viscosities in a Microchannel with Curved Stirrer by Lattice Boltzmann Method Numerical Simulation of Mixing Two Fluids of Different Viscosities in a Microchannel with Curved Stirrer by Lattice Boltzmann Method 3187 3202 3626 10.22060/mej.2019.16375.6349 FA Reza Kaveh Ph.D. Student, Departmet of Mechanical Engineering, University of Yazd, Yazd, Iran Mohammad Sefid mechanical engineering yazd university yazd Mohsen Mozafari Shamsi Assistant Professor, Departmet of Engineering, University of Meybod, Meybod, Iran Journal Article 2019 05 19 In the present study, mixing of two fluids of different viscosities in a micro channel with an oscillating curved stirrer was simulated by multi relaxation time Lattice Boltzmann method and the effect of geometric shape, oscillating speed and amplitude and viscosity logarithmic ratio on mixing efficiency was analyzed. In researches in this field, the stirrer is considered as cylinder or rectangle shape and in most these researches, two fluids are same. In this study, a curved stirrer was used for mixing two fluids of different viscosities in microchannel for the first time. Calculations are performed for the dimensionless parameters of the problem including the oscillation amplitude K, viscosity logarithmic ratio R and Strouhal number St for Re=80 and Sc=10. NASA/LANGLEY LS(1)-0417 (GA(W)-1) airfoil shape was used for curved stirrer. Results showed that mixing efficiency of two fluids of same and different viscosities in microchannel with oscillating curved stirrer was higher than microchannel with oscillating rectangle stirrer. In addition, results revealed that increase in Strouhal number causes increase in mixing efficiency on studied oscillating amplitude. 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. In the present study, mixing of two fluids of different viscosities in a micro channel with an oscillating curved stirrer was simulated by multi relaxation time Lattice Boltzmann method and the effect of geometric shape, oscillating speed and amplitude and viscosity logarithmic ratio on mixing efficiency was analyzed. In researches in this field, the stirrer is considered as cylinder or rectangle shape and in most these researches, two fluids are same. In this study, a curved stirrer was used for mixing two fluids of different viscosities in microchannel for the first time. Calculations are performed for the dimensionless parameters of the problem including the oscillation amplitude K, viscosity logarithmic ratio R and Strouhal number St for Re=80 and Sc=10. NASA/LANGLEY LS(1)-0417 (GA(W)-1) airfoil shape was used for curved stirrer. Results showed that mixing efficiency of two fluids of same and different viscosities in microchannel with oscillating curved stirrer was higher than microchannel with oscillating rectangle stirrer. In addition, results revealed that increase in Strouhal number causes increase in mixing efficiency on studied oscillating amplitude. 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. https://mej.aut.ac.ir/article_3626_0ee8b85a85a49346fdff9665312a5cc4.pdf