Stability of bifluid jets in microchannels

In this paper, a numerical tool is provided in order to study the stability of a confined coflowing jet in a cylindrical geometry. For a given configuration in which the flow rates, viscosities, diameter of the channel, and surface tension are the adjustable parameters, the length on which a jet is stable is computed. At low Reynolds number in a cylindrical geometry, two main configurations have been observed by Guillot et al. (2008) [19] on immiscible flows evolving in microchannels: the jet regime and the creation of droplets. The Rayleigh-Plateau instability is responsible for the break-up of a jet. To calculate the critical length, determined by the experimental settings, on which a jet can be stable, the linearization of a system of partial differential equations around the stationary solution describing the jet is performed. The growth rate of the perturbation is computed. The results are compared with experimental data, and a parametric study is supplied.