Open Access

ARTICLE

Effect of Libration on Fluid Flow and Granular Medium Dynamics in a Rotating Cylindrical Annulus

Denis Polezhaev^*, Alexey Vjatkin, Victor Kozlov

Laboratory of Vibrational Hydromechanics, Perm State Humanitarian Pedagogical University, Perm, 614990, Russia

* Corresponding Author: Denis Polezhaev. Email:

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

Fluid Dynamics & Materials Processing 2025, 21(5), 1051-1061. https://doi.org/10.32604/fdmp.2025.062000

Received 08 December 2024; Accepted 22 January 2025; Issue published 30 May 2025

Abstract

The dynamics of fluid and non-buoyant particles in a librating horizontal annulus is studied experimentally. In the absence of librations, the granular material forms a cylindrical layer near the outer boundary of the annulus and undergoes rigid-body rotation with the fluid and the annulus. It is demonstrated that the librational liquefaction of the granular material results in pattern formation. This self-organization process stems from the excitation of inertial modes induced by the oscillatory motion of liquefied granular material under the influence of the gravitational force. The inertial wave induces vortical fluid flow which entrains particles from rest and forms eroded areas that are equidistant from each other along the axis of rotation. Theoretical analysis and experiments demonstrate that a liquefied layer of granular material oscillates with a radian frequency equal to the angular velocity of the annulus and interacts with the inertial wave it excites. The new phenomenon of libration-induced pattern formation is of practical interest as it can be used to control multiphase flows and mass transfer in rotating containers in a variety of industrial processes.

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