Pattern selection in miscible liquids under periodic excitation in microgravity: Effect of interface width

• Published in: Physics of fluids (1994) 2018-06, Vol.30 (6)
• Main Authors: Gaponenko, Y., Mialdun, A., Shevtsova, V.
• Format: Article
• Language: English
• Subjects: Amplitudes; Computer simulation; Density; Fluid dynamics; Gravitational effects; Liquids; Microgravity; Miscibility; Parabolic flight; Physics; Stability
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/1.5032107

We develop a connection between instabilities in a two-liquid miscible system and in a liquid mixture with a linear distribution of density. In both cases, the liquids are placed in a closed cell and subjected to horizontal oscillations at different frequencies and amplitudes in a microgravity environment. The study includes parabolic flight experiments and numerical simulations. We examine the transformation of the interfacial pattern when the diffusive interface widens from a thin transient zone occupying 4% of the cell height to a situation when it occupies the entire cell height. In the case of sharp concentration (density) difference between miscible liquids, under reduced gravity conditions, instability leads to the formation of rectangular columns of liquids of alternating densities with an amplitude nearly equal to the height of the cell. The increase of the interface width promotes the selection of a smaller wave number associated with columns. The experimental observations are confirmed by the numerical simulations. In order to quantify the pattern regimes, we suggested to use the averaged mass flux through the mid-height of the cell.