Effect of parallel electric field on the linear stability between a Newtonian and a power-law fluid in a microchannel
Department of Chemical Engineering, Boğaziçi University, 34342, Istanbul, Turkey
Accepted: 30 January 2023
Published online: 2 March 2023
Applying an electric field to a two-fluid flow in a microchannel is an effective way to obtain microdroplets. For that purpose, the stability of the interface between a Newtonian and a power-law fluid flowing in a microchannel is studied. The fluids are either leaky dielectric or perfect dielectric. The effects of the applied voltage, the power-law index, and the strength of the base flow are investigated. Increasing the voltage may destabilize or stabilize the system depending on the electrical properties of the leaky dielectric fluids, similar to a system of two Newtonian fluids. When the electric field destabilizes the system, the maximum wavenumber increases, representing a droplet volume decrease. For perfect dielectric fluids, the electric field permanently stabilizes the flow independent of the electrical properties of fluids. The stability behavior of the power-law index depends on the fluids’ thickness ratio. When the power-law index is added as a new parameter, the base flow strength also affects the system stability, even when the thickness and viscosity ratios are unity, unlike two Newtonian fluid system. Depending on the fluids’ power-law index, and viscosity ratio, the base flow strength may stabilize or destabilize the system. Additionally, a sudden decrease in the droplet volume may be observed for some values of the power-law index and viscosity ratios.
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