Electrohydrodynamic instability between three immiscible fluids in a microchannel: lubrication analysis
Microfluidics and Nanofluidics, cilt.26, sa.2, 2022 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 26 Sayı: 2
- Basım Tarihi: 2022
- Doi Numarası: 10.1007/s10404-021-02516-w
- Dergi Adı: Microfluidics and Nanofluidics
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, PASCAL, Biotechnology Research Abstracts, Compendex, INSPEC
- Anahtar Kelimeler: Electrohydrodynamics, Lubrication, Microfluidics, Trilayer
- Boğaziçi Üniversitesi Adresli: Evet
Özet
When three immiscible, leaky dielectric, Newtonian fluids with finite physical properties are subjected to pressure-driven base flow in a microchannel, two flat interfaces are formed. The system can be destabilized by a direct current (DC) electric field, which is normal (vertical) to the interfaces to obtain the droplet of any phase. Linear stability analysis results are shown through dispersion and neutral stability curves, maximum growth rate, and its corresponding wavenumber. Nonlinear evolutions of the interfaces are studied under the lubrication assumption. The parameters, applied voltage, the thickness, and viscosity ratios, the strength of the base flows, are chosen based on their ease of experimental manipulation. It is shown that the base flow, which strongly depends on the viscosity ratios, does not only affect the oscillation period at the linear regime, but it also plays an important role in the stability both at the linear and the nonlinear regimes. An unstable system due to viscosity stratification can be stabilized, and a stable system can be destabilized by an applied electric field, which is shown analytically. The thickness ratio shows a non-monotonic behavior for the maximum growth rate. It can even lead to two maxima at the dispersion curve. It would be possible to get smaller droplets by increasing the applied voltage, the base flow strength, and the viscosity of the inner liquid. A major finding, which was not observed in the two-phase problem, is that by adjusting the thickness ratios, one may obtain the droplets of either the sandwiched or the encapsulating liquid.