Numerical Simulation of Mixing Two Fluids of Different Viscosities in a Micromixer at Different Aspect Ratios of Stirrer by LBM

Authors

1 Ph.D. Student, Departmet of Mechanical Engineering, University of Yazd, Yazd, Iran.

2 Associate Professor, Departmet of Mechanical Engineering, University of Yazd, Yazd, Iran.

3 Assistant Professor, Departmet of Engineering, University of Meybod, Meybod, Iran

Abstract

In the present study, mixing of two fluids of different viscosities in a micromixer with oscillating stirrer was simulated by MRT-LBM and the effect of aspect ratio (AR) of stirrer on mixing efficiency was analyzed. The simulation was performed at Re=50, Sc=10. The results showed that at low values of amplitude (K), at low values of Strouhal number (St), increase of AR causes increase in mixing efficiency and at other values of St it decreases and then increases. At intermediate values of K, at low and intermediate St, mixing efficiency decreases with the increase of AR and at high values of St, it first decreases and then increases. At high values of K, at low and high St, increasing AR causes no improvement in mixing efficiency and at intermediate values of St, mixing efficiency decreases and then increases. In this research, the best mixing efficiency for viscosity logarithmic ratio (R) =2 is at AR=0.7, St=1, K=0.5.
The effect of AR and St on mixing efficiency at different R was analyzed and results revealed that for two fluids of different viscosities, at very low values of St, mixing efficiency increases with the increase of R and at others decreases considerably. In general, for two fluids of different viscosities, stirrer with low values of AR has better mixing efficiency.

Keywords

Main Subjects

References

[1]  Nguyen NT (1970). Micromixers: Fundamentals, design and fabrication. William Andrew.
[2] Hessel V, Löwe H, Schönfeld F (2005) Micromixers—a review on passive and active mixing principles. Chem Eng Sci 60(8-9): 2479-2501.
[3] Capretto L, Cheng W, Hill M, Zhang X (2011) Micromixing within microfluidic devices. In Microfluidics (pp. 27-68). Springer, Berlin, Heidelberg.
[4] Park, JY, Kim, YD, Kim SR., Han, SY, Maeng JS (2008) Robust design of an active micro-mixer based on the Taguchi method. Sensor Actuat B-Chem 129(2): 790-798.
[5] Koch M, Witt H, Evans AGR, Brunnschweiler A (1999) Improved characterization technique for micromixers. J Micromech Microeng 9(2), 156.
[6] Liu YZ, Kim BJ, Sung HJ (2004) Two-fluid mixing in a microchannel. Int J Heat Fluid Fl 25(6): 986-995.
[7] Liu RH, Stremler MA, Sharp KV, Olsen MG, Santiago JG, Adrian RJ, Beebe DJ (2000) Passive mixing in a three-dimensional serpentine microchannel. J MIcroelectromech S 9(2): 190-197.
[8] An SJ, Kim YD, Heu S, Maeng JS (2006) Numerical study of the mixing characteristics for rotating and oscillating stirrers in a microchannel. J Korean Phys Soc 49(2): 651-659.
[9] Jin SY, Liu YZ, Wang WZ, Cao ZM, Koyama HS (2006) Numerical evaluation of two-fluid mixing in a swirl micro-mixer. J Hydrodyn 18(5): 542-546.
[10] Kim YD, An SJ, Maeng JS (2007) Numerical analysis of the fluid mixing behaviors in a microchannel with a circular cylinder and an oscillating Stirrer. J Korean Phys Soc 50: 505-513.
[11] Celik, B., Akdag, U., Gunes, S., & Beskok, A. (2008). Flow past an oscillating circular cylinder in a channel with an upstream splitter plate. Phys Fluids, 20(10), 103603.
[12] Celik B, Beskok A (2009) Mixing induced by a transversely oscillating circular cylinder in a straight channel. Phys Fluids 21(7), 073601.
[13] Im M, Park JY, Oh YK, Kim YD, Maeng JS, Han SY (2009) Microfluidic analysis of a micro-mixer with an oscillating stirrer.
[14] Shamsoddini R, Sefid M, Fatehi R (2014) ISPH modelling and analysis of fluid mixing in a microchannel with an oscillating or a rotating stirrer. Eng Appl Comp Fluid 8(2): 289-298.
[15] Ortega-Casanova J (2016) Enhancing mixing at a very low Reynolds number by a heaving square cylinder. J Fluid Struct 65: 1-20.
[16] Ortega-Casanova J (2017) CFD study on mixing enhancement in a channel at a low Reynolds number by pitching a square cylinder. Comput Fluids 145: 141-152.
[17] Ghanbari S, Sefid M, Shamsoddini R (2016) Numerical Analysis of two-fluid mixing with various Density and Viscosity in a microchannel with forced oscillating stirrer. Modares Mechanical Engineering 16(8): 109-119.
[18] Khozeymeh-Nezhad H, Niazmand H (2017) A numerical analysis of an active micromixer with the oscillating stirrer at the different aspect ratios by LBM. Modares Mechanical Engineering 17(9): 417-426.
[19] Khozeymeh-Nezhad H, Niazmand H (2018) A double MRT-LBM for simulation of mixing in an active micromixer with rotationally oscillating stirrer in high Peclet number flows. Int J Heat Mass Tran 122: 913-921.
[20] Talon L, Meiburg E (2011) Plane Poiseuille flow of miscible layers with different viscosities: instabilities in the Stokes flow regime. J Fluid Mech 686: 484-506.
[21] Lallemand P, Luo LS (2003) Theory of the lattice Boltzmann method: Acoustic and thermal properties in two and three dimensions. Phys Rev E 68(3): 036706.
[22] Guo Z, Shu C (2013) Lattice Boltzmann method and its applications in engineering (Vol. 3). World Scientific.
[23] Li L, Mei R, Klausner JF (2017) Lattice Boltzmann models for the convection-diffusion equation: D2Q5 vs D2Q9. Int J Heat Mass Tran 108: 41-62.
[24] Zou Q, He X (1997) On pressure and velocity boundary conditions for the lattice Boltzmann BGK model. Phys Fluids 9(6): 1591-1598.
[25] Guo Z, Zheng C, Shi B (2002) An extrapolation method for boundary conditions in lattice Boltzmann method. Phys Fluids 14(6): 2007-2010.
[26] Li L, Mei R, Klausner JF (2013) Boundary conditions for thermal lattice Boltzmann equation method. J Comput Phys 237: 366-395.
[27] Lallemand P, Luo LS (2003) Lattice Boltzmann method for moving boundaries. J Comput Phys 184(2): 406-421.
Journal of Solid and Fluid Mechanics
Volume 9, Issue 1
April 2019
Pages 187-202

Files

Share

How to cite

Statistics