Abstract
Microfluidic devices are widely used in microbiology, fine organic synthesis, pharmaceuticals, biomedicine, etc. Most applications require rapid mixing of the fluids that pass through the microfluidic chip. Continuous-flow microreactors used in flow chemistry have a characteristic channel size that is small enough, compared to standard laboratory size in fluid mechanics but large enough to render the diffusion mixing mechanism ineffective. In this work, we study, experimentally and theoretically, the efficiency of using various mechanisms of natural convection for the mixing of fluids entering the microfluidic chip. Solutions typically differ in buoyancy and diffusion rates of solutes, making them sensitive to gravity-dependent instabilities such as Rayleigh-Taylor convection, double diffusion, and diffusion layer convection. We consider a Y-shaped microreactor, which is, on the one hand, the simple scheme of mixing and, on the other hand, a typical element of a microfluidic network. We assume that two miscible solutions independently enter through different tubes into a common channel, where they come into contact and begin to mix. For simplicity, we do not consider chemical reactions in this paper. For each type of instability, we numerically estimated the characteristic channel length, after which complete mixing of the solutions occurs. The numerical simulations are performed in the framework of the 3D model. Finally, we compare the experimental data and numerical results.
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Data Availability
The datasets generated during and/or analysed during the current study are available at the web address: https://disk.yandex.ru/d/o-AN5z1TQV7OPA.
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Funding
This study was funded by Perm National Research Polytechnic University in the framework of the federal academic leadership program “Priority 2030”. Also, E.M. wishes to thank the Scholarship of RF President for young scientists (no. SP-2408.2021.1) and the Ministry of Science and High Education of Russia (theme no. 121031700169-1) for the financial support.
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Bratsun, D.A., Siraev, R.R., Pismen, L.M. et al. Mixing Enhancement By Gravity-dependent Convection in a Y-shaped Continuous-flow Microreactor. Microgravity Sci. Technol. 34, 90 (2022). https://doi.org/10.1007/s12217-022-09994-9
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DOI: https://doi.org/10.1007/s12217-022-09994-9