title: Band instability in near-critical fluids subjected to vibration under weightlessness.
abstract: Periodical patterns (bands) developing at the interface of two immiscible fluids under vibration parallel to interface are observed under zero-gravity conditions. Fluids are slightly below their liquid-vapor critical point where they behave in a scaled, universal manner. In addition, liquid and vapor densities are close and surface tension is very low. Linear stability analyses and direct numerical simulation show that this instability, although comparable to the frozen wave instability observed in a gravity field, is nonetheless noticeably different when gravity becomes zero. In particular, the neutral curve minimum corresponds to the long-wave perturbations with k=0 and zero dimensionless vibrational parameter, corresponding to no instability threshold. The pattern wavelength thus corresponds to the wavelength of the perturbations with maximal growth rate. This wavelength differs substantially from the neutral perturbations wavelength at the same vibrational parameter value. The role of viscosity is highlighted in the pattern formation, with a critical wavelength dependence on vibration parameters that strongly depends on viscosity. These results compare well with experimental observations performed in the liquid-vapor phases near the critical point of CO_{2} (in weightlessness) and H_{2} (under magnetic levitation).
authors.affiliation: Institute of Continuous Media Mechanics UB RAS, 1, Koroleva Street, 614013 Perm, Russia.|Perm State University, 15, Bukireva Street 614990 Perm, Russia.
authors.forename: T
authors.initials: T
authors.lastname: Lyubimova
authors.affiliation: Institute of Continuous Media Mechanics UB RAS, 1, Koroleva Street, 614013 Perm, Russia.|Perm State University, 15, Bukireva Street 614990 Perm, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Ivantsov
authors.affiliation: CNRS, ICMCB, ESEME, UPR 9048, F-33600 Pessac, France.|Université Bordeaux, ICMCB, UPR 9048, F-33600 Pessac, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Garrabos
authors.affiliation: CNRS, ICMCB, ESEME, UPR 9048, F-33600 Pessac, France.|Université Bordeaux, ICMCB, UPR 9048, F-33600 Pessac, France.
authors.forename: C
authors.initials: C
authors.lastname: Lecoutre
authors.affiliation: Service des Basses Températures, CEA-Grenoble and Université Joseph Fourier, F-38000 Grenoble, France.
authors.forename: G
authors.initials: G
authors.lastname: Gandikota
authors.affiliation: Service des Basses Températures, CEA-Grenoble and Université Joseph Fourier, F-38000 Grenoble, France.|Physique et Mécanique des Milieux Hétérogènes, UMR 7636 CNRS-ESPCI-Université Pierre et Marie Curie-Université Paris Diderot, 10 rue Vauquelin, 75005 Paris, France.
authors.forename: D
authors.initials: D
authors.lastname: Beysens