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Communication Dans Un Congrès Année : 2018

Suppression of the Kapitza instability in falling liquid films by confining the gas phase

Résumé

We address the linear stability of inclined falling liquid films in confined channels. We revisit the two-phase temporal Orr-Sommerfeld problem and investigate the role of the confinement upon the Kapitza instability with both aerostatic and counter-current gas flow. Increasing the confinement provides a strong stabilizing effect on the liquid film, with a reduction of the cut-off wavenumber along with an increase of the critical Reynolds number, as shown in Figure 1. In the presence of a counter-current gas flow, the increase of the gas flow rate induces interfacial stability at strong confine- ment. We show that the Kapitza instability can be fully suppressed at low angles of inclination and relatively strong confinements. A parametric study of the influence of the confinement by varying the Reynolds number, the inclination angle and the Kapitza number is also provided. We validate the numerical solution of the Orr-Sommerfeld temporal linear stabil- ity problem by comparison with experimental data of cut-off frequency and spatial growth rate, as well as with previous numerical works. The stabilizing effect of the confinement is due to the perturbation of the interfacial tangential shear stress which, in fact, attenuates the growth of the wave crest by reducing the inertial effects, which in turn are responsible for the instability.
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Dates et versions

hal-02020918 , version 1 (15-02-2019)

Identifiants

  • HAL Id : hal-02020918 , version 1

Citer

Gianluca Lavalle, Yiqin Li, S. Mergui, Nicolas Grenier, G. Dietze. Suppression of the Kapitza instability in falling liquid films by confining the gas phase. European Fluid Mechanics Conference, Sep 2018, Vienne, Austria. ⟨hal-02020918⟩
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