Optimization of Micromixer with Staggered Herringbone Grooves on Top and Bottom Walls

Abstract Multi-objective shape optimization of a micromixer with staggered herringbone grooves on the top and bottom walls has been performed through three-dimensional Navier–Stokes analysis, surrogate method and multi-objective evolutionary algorithm. Mixing index and friction factor are selected as objective functions, and four design variables, viz., number of grooves per half cycle (N), angle of groove (θ), groove depth to channel height ratio (d/h), and groove width to pitch ratio (Wd/pi) are chosen out of the various geometric parameters which affect the performance of the micromixer for the shape optimization. Numerical analysis has been performed with two working fluids, viz., water and ethanol at Reynolds number 1. The variance of the mass fraction at various nodes on a plane is used to quantify the mixing performance in the micromixer. The design space is explored through some preliminary calculations and a Latin hypercube sampling method is used as a design of experiments to exploit the design space. Response surface approximation model is constructed using numerical solutions at the designed-sites. The trade-off between the two competing objective functions has been found and discussed in the light of the distribution of Pareto-optimal solutions in the design space. It is observed that the Pareto-optimal solutions shift towards lower values of the design variables θ and wd/pi, and towards higher value of the design variable d/h whereas the design variable N remains insensitive along the Pareto-optimal front in the direction of higher mixing index.

[1]  N. Lynn,et al.  Geometrical optimization of helical flow in grooved micromixers. , 2007, Lab on a chip.

[2]  Douglas C. Montgomery,et al.  Response Surface Methodology: Process and Product Optimization Using Designed Experiments , 1995 .

[3]  Hengzi Wang,et al.  Numerical investigation of mixing in microchannels with patterned grooves , 2003 .

[4]  Kevin Tucker,et al.  Response surface approximation of pareto optimal front in multi-objective optimization , 2004 .

[5]  Eun Sok Kim,et al.  Novel acoustic-wave micromixer , 2000, Proceedings IEEE Thirteenth Annual International Conference on Micro Electro Mechanical Systems (Cat. No.00CH36308).

[6]  Kwang-Yong Kim,et al.  Application of the Radial Basis Neural Network to Optimization of a Micromixer , 2007 .

[7]  Ramana M. Pidaparti,et al.  Performance Evaluation of a Micropump with Multiple Pneumatic Actuators Via Coupled Simulations , 2010 .

[8]  Jing-Tang Yang,et al.  Fluids mixing in devices with connected-groove channels , 2008 .

[9]  Jing-zhou Zhang,et al.  Experimental and Numerical Studies on Lobed Ejector Exhaust System for Micro Turbojet Engine , 2011 .

[10]  M. A. Ansari,et al.  Shape optimization of a micromixer with staggered herringbone groove , 2007 .

[11]  D. Hassell,et al.  Investigation of the convective motion through a staggered herringbone micromixer at low Reynolds number flow , 2006 .

[12]  R. K. Ursem.  Multi-objective Optimization using Evolutionary Algorithms , 2009 .

[13]  Abolfazl Khalkhali,et al.  Pareto Based Multi-Objective Optimization of Centrifugal Pumps Using CFD, Neural Networks and Genetic Algorithms , 2011 .

[14]  Peter B Howell,et al.  A microfluidic mixer with grooves placed on the top and bottom of the channel. , 2005, Lab on a chip.

[15]  David Erickson,et al.  Towards numerical prototyping of labs-on-chip: modeling for integrated microfluidic devices , 2005 .

[16]  Q. M. Jonathan Wu,et al.  An Optimized Micromixer with Patterned Grooves , 2004, 2004 International Conference on MEMS, NANO and Smart Systems (ICMENS'04).

[17]  I. Mezić,et al.  Chaotic Mixer for Microchannels , 2002, Science.

[18]  D. K. Pratihar,et al.  Optimum Design of a Two Step Planar Diffuser: A Hybrid Approach , 2010 .

[19]  W. M. Haynes.  CRC Handbook of Chemistry and Physics , 1990 .

[20]  T. Johnson,et al.  Characterization and optimization of slanted well designs for microfluidic mixing under electroosmotic flow. , 2002, Lab on a chip.

[21]  Jing-Tang Yang,et al.  Geometric effects on fluid mixing in passive grooved micromixers. , 2005, Lab on a chip.

[22]  Steffen Hardt,et al.  Laminar mixing in different interdigital micromixers: II. Numerical simulations , 2003 .

[23]  T. G. Kang,et al.  Colored particle tracking method for mixing analysis of chaotic micromixers , 2004 .

[24]  L S Pan,et al.  CFD Simulations of Flows in Valveless Micropumps , 2007 .

[25]  Akira Goto,et al.  On multi-objective optimization of geometry of staggered herringbone micromixer , 2009 .

[26]  Fangjun Hong,et al.  A numerical study of an electrothermal vortex enhanced micromixer , 2008 .