Diffusion and convection mixing of non‐Newtonian liquids in an optimized micromixer

Abstract

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.

Maximum Spreading and Rebound of a Droplet Impacting onto a Spherical Surface at Low Weber Numbers

“…Droplet impact onto solid surfaces is a phenomenon frequently observed in both nature and engineering applications. 1 Common examples include impact onto plant leaves, 2 internal combustion engines where fuel droplets interact with piston and liner walls, 3 inkjet printing, 4,5 droplet-based microfluidics, 6,7 anti-icing, 8 spray cooling, 9,10 crude oil industry, 11 etc. There are also many applications in chemical and petroleum processing, such as fluid catalytic cracking (FCC) where atomized droplets are brought into contact with high temperature fluidized catalyst particles.…”

Improvement of mass and heat transfer efficiency in a scale‐up microfluidic mixer designed by CFD simulation

“…Nusselt number is the ratio of convective heat across the boundary to conducted heat. The formula of the Nusselt number is [33,34] :…”

Design and Analysis of a Laminar Diffusion-Based Micromixer with Microfluidic Chip

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