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Stability of a Jet in Confined Pressure-Driven Biphasic Flows at Low Reynolds Numbers

P. Guillot, A. Colin, A. S. Utada, and A. Ajdari — Phys. Rev. Lett. 99, 104502 (2007)

publié le , mis à jour le

Motivated by its importance for microfluidic applications, we study the stability of jets formed by
pressure-driven concentric biphasic flows in cylindrical capillaries. The specificity of this variant of the
classical Rayleigh-Plateau instability is the role of the geometry which imposes confinement and
Poiseuille flow profiles. We experimentally evidence a transition between situations where the flow takes
the form of a jet and regimes where drops are produced. We describe this as the transition from convective
to absolute instability, within a simple linear analysis using lubrication theory for flows at low Reynolds
number, and reach remarkable agreement with the data.