Premium
Diffusion and convection mixing of non‐Newtonian liquids in an optimized micromixer
Author(s) -
Bordbar Alireza,
Taassob Arsalan,
Kamali Reza
Publication year - 2018
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23113
Subject(s) - reynolds number , micromixer , mechanics , shear thinning , newtonian fluid , pressure drop , laminar flow , non newtonian fluid , transition point , advection , rheology , thermodynamics , materials science , physics , turbulence , microfluidics
An optimized planar micromixer has been employed to study its performance in mixing liquids with various rheological behaviours. This design takes advantage of a number of passive techniques, including split‐and‐recombination of the channel, contraction of the channel, and embedding diamond‐shaped obstacles in the main channels. Three‐dimensional Navier‐Stokes equations, along with an advection‐diffusion model are solved by means of a finite‐element scheme. Numerical simulations are performed for species with power law indexes ranging from 0.6–1.4, and the resulting mixing efficiencies are compared for different cases. Pressure drop is also evaluated and compared by taking into account the rheological behaviour of the fluids. The results revealed that in the studied range of Reynolds numbers, shear‐thickening fluids present higher efficiencies in the diffusion‐dominated regimes by 5 % at the best case. Shear‐thinning flows have a better performance at higher Reynolds numbers and expedite the diffusion‐advection transition point compared to other regimes. Transition occurs at a Reynolds number of 0.1 for the shear‐thinning regime, while for Newtonian fluids this point is at a Reynolds number equal to 1. Moreover, it is found that the variation of mixing efficiency for shear‐thickening flows with different fluid behaviour indexes is not significant in the studied Reynolds number range.