Publication: Enhanced liquid mixing in 2d channel with different fin configurations
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Date
2022-08-01
Authors
Tan, Sak Jie
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Abstract
In microfluidic devices, narrow channels lead to low Reynolds number flows, thereby restricting the fluid flow in a laminar flow condition, a long mixing channel length is thus needed to achieve a complete mixing. The research on liquid mixing enhancement in the channel shall be explored to reduce the required mixing length. The assessment of liquid mixing in the channel was performed to investigate the fluid flow in the channel with augmented design. The experiment on channels with the augmented designs was performed in the study to mimic the mixing behavior in the channel. The combination of different inlet designs, for example, Cross-inlet and T-inlet integrated with staggered fins, were modelled to numerically investigate the mixing performance. It is found that the implementation of obstacles within the channel can significantly enhance the mixing performance. The numerical investigation on the effects of geometric parameters and flow parameters on the Cross-mixer and T-mixer were performed in this study. Several fin arrangements, such as staggered fin arrangement, in-line fin arrangement, and Tri-fin arrangement on T-mixer, were proposed to enhance the mixing performance on the mixer. At 𝑥/𝐻 = 10, 𝑀 of 0.8905 is attained with staggered fin arrangement. Meanwhile, 𝑀 = 0.8509, 0.8498, and 0.7443 are yielded with in-line fin, Tri-fin and basic mixer, respectively, at the same axial position. Among these designs, T-mixer with staggered fin arrangement yielded the best mixing performance, in the practical range of Reynolds numberinvestigated. Besides, the comparison between Cross-mixer and conventional mixers was also examined. The results show that well-mixed fluid can be achieved with only a one-quarter channel length using Cross-mixer as compared with conventional mixers (T-mixer and Y-mixer) under the same flow condition. The correlation equation for T-mixer and Cross-mixer is proposed to predict the mixing length based on the Péclet number. The correlations are in good agreement with the simulation results. The effect on Péclet number and the validity of 3D mixers were also presented to validate the proposed correlations. Apart from that, the proposed correlation equation for Cross-mixer is validated by comparing the experimental results of the Cross-mixer at Re = 12 to 67. The correlation formulation proposed is found to be in good agreement with the experimental results. The deviation between numerical simulation and proposed correlation for T-mixer and Cross-mixer are 1.69 % and 0.89 %, respectively. These correlations shall be useful for researchers in predicting the mixing length without the need to perform numerical simulation.