Abstract
Sample mixing is difficult in microfluidic devices because of laminar flow. Micromixers are designed to ensure the optimal use of miniaturized devices. The present study aims to design a chaotic-advection-based passive micromixer with enhanced mixing efficiency. A serpentine-shaped microchannel with sinusoidal side walls was designed, and three cases, with amplitude to wavelength (A/λ) ratios of 0.1, 0.15, and 0.2 were investigated. Numerical simulations were conducted using the Navier–Stokes equations, to determine the flow field. The flow was then coupled with the convection–diffusion equation to obtain the species concentration distribution. The mixing performance of sinusoidal walled channels was compared with that of a simple serpentine channel for Reynolds numbers ranging from 0.1 to 50. Secondary flows were observed at high Reynolds numbers that mixed the fluid streams. These flows were dominant in the proposed sinusoidal walled channels, thereby showing better mixing performance than the simple serpentine channel at similar or less mixing cost. Higher mixing efficiency was obtained by increasing the A/λ ratio.
Highlights
Microfluidic devices use fluid flow at the submillimeter scale for applications in areas such as life sciences, analytical chemistry, and bioengineering
This paper reports the results of a numerical study on the mixing performance of a chaotic-advection-based serpentine microchannel with sinusoidal side walls
The cost of mixing should be determined. This mixing cost is calculated in terms of pressure drop using the mixing index to pressure drop (MI/∆P) ratio [34], or in terms of input power [35]
Summary
Microfluidic devices use fluid flow at the submillimeter scale for applications in areas such as life sciences, analytical chemistry, and bioengineering. Serpentine channels can be employed to achieve high mixing efficiency and damage-free processing of samples Modifications, such as the use of non-aligned inputs [29] and three-dimensional serpentine geometries have been shown to further enhance the mixing performance of serpentine channels [28]. This paper reports the results of a numerical study on the mixing performance of a chaotic-advection-based serpentine microchannel with sinusoidal side walls. The present study presents a modified geometry that was designed using sinusoidal side walls in a serpentine channel to increase the secondary flow because of change in Dean number, and attain better mixing than a simple serpentine channel. Designed using sinusoidal side walls in a serpentine channel to increase the secondary flow because of change in Dean number, and attain better mixing than a simple serpentine channel.
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