Steady axial electric field may lead to controllable cross-stream migration of droplets in confined oscillatory microflows

Somnath Santra,Suman Chakraborty

doi:10.1017/jfm.2020.789

Somnath Santra, Suman Chakraborty

Open Access

https://doi.org/10.1017/jfm.2020.789

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Abstract

Highlights

Precise manipulation and sorting of soft entities in microfluidic systems have received remarkable attention in contemporary research, as attributable to their diverse applications in physical, biological and engineering systems
In sharp contrast to reported theory (Mandal et al 2016) that depicts the possibility of cross-stream migration of a droplet only if subjected to a tilted electric field, we show that confinement-induced electrohydrodynamic interactions enable the spatiotemporal characteristics of lateral motion of a droplet to be controlled even in the presence of an electrical field that is orthogonal to the direction of the droplet migration
The two-dimensional (2-D) computational domain is shown in figure 1, where a neutrally buoyant leaky dielectric droplet is suspended in another leaky dielectric medium under the combined governance of oscillatory pressure-driven background flow and uniform axial electric field

Summary

Introduction

Several reported studies pointed out that the migration characteristic of a droplet can be modulated by altering the deformability of the interface (Goldsmith & Mason 1962; Chaffey, Brenner & Mason 1965; Haber & Hetsroni 1971; Wohl & Rubinow 1974; Stan et al 2011; Mandal et al 2015a), fluid properties (Chan & Leal 1979; Mukherjee & Sarkar 2013, 2014; Hazra, Mitra & Sen 2019), flow inertia (Ho & Leal 1974; Mortazavi & Tryggvason 2000; Chen et al 2014) and the nature of flow (steady or oscillatory)(Graham & Higdon 2000a, 2002; Chaudhury, Mandal & Chakraborty 2016) In addition to these factors, mutual interactions between electric forcing and domain confinement can be used as a means of fine-tuning the modulation of the droplet’s motion (Deshmukh & Thaokar 2012; Esmaeeli 2016; Zhang et al 2016; Brosseau & Vlahovska 2017; Nath et al 2018; Santra, Mandal & Chakraborty 2018b, 2019a; Poddar et al 2019a)

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