Oscillatory transverse instability of interfacial waves in horizontally oscillating flows

• Published in: Physics of fluids (1994) 2012-04, Vol.24 (4), p.044104-044104-11
• Main Authors: Jalikop, Shreyas V., Juel, Anne
• Format: Article
• Language: English
• Subjects: Breakup; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Hydrodynamic stability; Instability; Interfacial instability; Liquids; Oscillating flow; Oscillations; Physics; Secondary instability; Stability; Viscosity
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/1.4704602

We present the results of an experimental investigation into the stability of steep interfacial waves in two immiscible liquid layers subject to horizontal oscillations. Two-dimensional waves, which arise beyond a critical forcing speed V c (product of forcing frequency and amplitude), can in turn lose stability to oscillatory transverse amplitude modulations with a near sub-harmonic response at a critical value of the forcing speed, V cs > V c . We characterize the resulting transverse waves and study the effect of viscosity on the onset of this secondary instability. Our experiments show that V cs increases with the ratio of the viscosities of the two liquids, N ⩾ 1, which is in contrast to the decreasing trend of V c . The thresholds converge with decreasing N but appear to remain distinct even as N → 1. However, our results suggest a change of behavior for N ⩽ 39, which also coincides with the first observations of interface breakup.