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ARTICLE

Effect of Surface Tension on the Dynamics of an Oscillating Interface in a Vertical Slotted Channel

Veronika Dyakova^1,2,*, Olga Vlasova¹, Victor Kozlov¹

1 Laboratory of Vibrational Hydromechanics, Perm State Humanitarian Pedagogical University, Perm, 614000, Russia
2 Department of Applied Physics, Perm National Research Polytechnic University, Perm, 614990, Russia

* Corresponding Author: Veronika Dyakova. Email:

(This article belongs to the Special Issue: Non-Equilibrium Processes in Continuous Media)

Fluid Dynamics & Materials Processing 2025, 21(3), 493-508. https://doi.org/10.32604/fdmp.2025.060577

Received 05 November 2024; Accepted 22 January 2025; Issue published 01 April 2025

Abstract

An experimental investigation of the dynamics of the interface between two low-viscosity fluids with high density contrast oscillating in a fixed vertical slotted channel has been conducted. It has been found that as the amplitude of the liquid column oscillations increases, parametric oscillations of the interface are excited in the form of a standing wave located in the channel plane. In particular, depending on the interfacial tension, the standing waves have a frequency equal to that of liquid piston oscillations (harmonic response), or half of the frequency of oscillations of the liquid column in the channel (subharmonic response). The detected type of instability has a gravitational-capillary nature and is analogous to Faraday waves. The analysis of the overcritical dynamics of wave oscillations indicates that interfacial tension plays a crucial role in determining the type of parametric instability. At high interfacial tension, only synchronous (harmonic) wave modes are observed, and the threshold of the wave excitation is determined by the amplitude of piston oscillations of the liquid column. In this case, the oscillation acceleration does not play a role and has a small value in the threshold of the synchronous mode response. In the case of weak surface tension, subharmonic oscillations are observed. The threshold for the development of these oscillations is determined by the dimensionless acceleration of the oscillating liquid column and remains almost constant with variations in the dimensionless frequency of oscillations. At moderate values of interfacial tension (in the region of moderate dimensionless frequencies), a synchronous wave mode emerges in the stability threshold of the oscillating interface. As the dimensionless acceleration is increased further, a subharmonic mode is excited. The growth of subharmonic oscillations occurs against the background of harmonic wave oscillations, with the oscillations of the interface representing a combination of two standing waves.

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Keywords

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