Numerical evaluation of swirl effect on liquid mixing in a passive T-micromixer

ABSTRACT

Micromixers are being extensively used in micro total analysis systems (µTAS) and chemical processing. Passive micromixers are most preferable due to their robustness, ease of integration and low cost. However, it is difficult to achieve rapid mixing in passive mixers. Previous studies on passive T-mixer showed that convective effects at high Reynolds number improve mixing significantly. In the present study, a swirl component of velocity is imparted at inlets of T-mixer to enhance the convective effects. Numerical results have shown that the reverse orientation of the swirl (R-O-Swirl) in inlet channels favored earlier onset of engulfment regime which enhanced mixing at lower Reynolds number (66 < Re < 180). At high Reynolds number (Re > 266), swirl with same orientation (S-O-Swirl) in inlet channels increased the swapping of samples at junction which significantly improved mixing. Nearly three hundred to five hundred percent increase in mixing index is obtained with R-O-Swirl at 160 < Re < 180 and thirty to seventy percent increment with S-O-Swirl at 266 < Re < 372 as compared to T-mixer without swirl. Therefore, it is noted that the presence of swirl component at inlets can further enhance the engulfment regime and improve mixing efficiency of T-micromixer.

KEYWORDS:

• Computational fluid dynamics
• micromixers
• mixing quality
• Swirl flow
• T-mixer
• vortex flow

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

T Manoj Dundi

T Manoj Dundi is a Ph.D. student at National Institute of Technology Warangal, India, under the supervision of Dr. V.R.K. Raju and Co-Supervision of Dr. V.P. Chandramohan. He received B.Tech in mechanical engineering from J.N.T.U Anantapur, Andhra Pradesh in 2009 and M.Tech in Thermal Engineering from IIT Madras, Tamil Nadu in 2011. He is currently working in Numerical Analysis of Liquid Mixing in Passive Micromixers.

V. R. K. Raju

Dr. V. R. K. Raju is Associate Professor of Mechanical Engineering at National Institute of Technology Warangal, India. He received his B.E. from University College of Engineering Burla, India in 1997, M.Tech from Jadavpur University, India in 2000 and his Ph.D. degree from Indian Institute of Technology, Kharagpur, India in 2011. He has been teaching at National Institute of Technology Warangal, India since 2012. His research contributions are in the field of Fluid Dynamics, Heat Transfer, CFD, Combustion, Microfluidics, Solar drying. He is currently working on Microfluidics, combustion and solar drying.

V. P. Chandramohan

Dr. V. P. Chandramohan  is Associate Professor of Mechanical Engineering at National Institute of Technology Warangal, India. He received his M.E degree from Annamalai University, Tamilnadu in 2002 and his Ph.D. degree from Indian Institute of Technology, Delhi in 2012. He has been teaching at National Institute of Technology Warangal since 2013. His research contributions were in the field of (i) Computational Fluid Dynamics (ii) Convection and conduction heat transfer (iii) Drying and Simultaneous solution of heat and mass transfer (iv) Solar energy (v) Alternative fuels and Hydrogen fuel cell. He has received various awards such as Sathik prize, Sciencedirect Top 25 Award, DST Empowerment scheme award etc. He is currently working on solar dryer and solar updraft tower.