Open Access

ARTICLE

Dynamics of Low-Viscosity Liquids Interface in an Unevenly Rotating Vertical Layer

by Victor Kozlov^1,*, Vladimir Saidakov¹, Nikolai Kozlov²

1 Laboratory of Vibrational Hydromechanics, Perm State Humanitarian Pedagogical University, Perm, 614990, Russia
2 Institut de Mécanique des Fluides de Toulouse, Toulouse INP, Toulouse, 31400, France

* Corresponding Author: Victor Kozlov. Email:

(This article belongs to the Special Issue: Advanced Problems in Fluid Mechanics)

Fluid Dynamics & Materials Processing 2024, 20(4), 693-703. https://doi.org/10.32604/fdmp.2024.048068

Received 27 November 2023; Accepted 15 December 2023; Issue published 28 March 2024

Abstract

The behavior of two immiscible low-viscosity liquids differing in density and viscosity in a vertical flat layer undergoing modulated rotation is experimentally studied. The layer has a circular axisymmetric boundary. In the absence of modulation of the rotation speed, the interphase boundary has the shape of a short axisymmetric cylinder. A new effect has been discovered, under the influence of rotation speed modulation, the interface takes on a new dynamic equilibrium state. A more viscous liquid covers the end boundaries of the layer in the form of thin films, which have the shape of round spots of almost constant radius; with increasing amplitude of the velocity modulation, the wetting boundary expands. It is found that upon reaching the critical amplitude of oscillations, the film of a viscous liquid loses stability, and the outer edge of the wetting spot collapses and takes on a feathery structure. It is shown that this threshold is caused by the development of the Kelvin–Helmholtz oscillatory instability of the film. The spreading radius of a spot of light viscous liquid and its stability are studied depending on the rotation rate, amplitude, and frequency of rotation speed modulation. The discovered averaged effects are determined by different oscillatory interaction of fluids with the end-walls of the cell, due to different viscosities. The effect of films forming can find application in technological processes to intensify mass transfer at interphase boundaries.

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Keywords

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