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    Instability analysis of the cone–jet flow in liquid-driven flow focusing

    Article obtained from Springer RSS Feed.

    Abstract

    The instability behaviors of a liquid jet issuing from a cone in liquid-driven flow focusing for droplet generation are studied. The experiment, numerical simulation by solving the Navier–Stokes equation coupled with a diffuse interface method, and linear spatio-temporal instability analysis based on non-uniform velocity profiles are performed. Typical flow modes and transitions are obtained by adjusting the flow rates of focused and focusing phases. The cone instability is examined and the flow patterns in the vicinity of the cone are presented numerically. The result shows that the liquid cone can be always stable in a wide range of process parameters when the viscous shear stress overcomes the interfacial tension stress and a scaling law is given. In addition, the spatial evolution of velocity profiles of the flow is numerically investigated. Finally, the jetting–dripping (J–D) transition is studied through the dimensional analysis and the linear instability theory in comparison with experiments and good agreements among them are achieved. It is also indicated that the J–D transition boundary can be approximately given by the scaling law of

    (We_{mathrm{i}}+Ca_{mathrm{o}}approx 1,)

    where

    (We_{mathrm{i}})

    and

    (Ca_{mathrm{o}})

    reflect the competitions of inertia force and viscous shear stress to the interfacial tension along the jet, respectively.

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    Nov, 15 2018 |

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