preprints.org > engineering > mechanical engineering > doi: 10.20944/preprints202408.1696.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 22 August 2024 / Approved: 23 August 2024 / Online: 25 August 2024 (06:23:30 CEST)

The tea leaf paradox (TLP) describes unsteady fluid motions which help entrain and deposit suspended particles at the center of rotation. Various applications depend on the TLP for particle separations spanning across orders of magnitude in length scales and is an important problem in fluid mechanics. Despite papers describing the phenomena, the efficacy of particle separation using the TLP remains unclear as to the relative importance of for example hydrostatics, particle-fluid density ratio, wall friction, liquid bath aspect ratio and the rotation speed. The dynamics involved are notably complex and require a careful tuning of each variable. In this study, we have investigated the role of the limit of the aggregation dynamics in rotational flows within 3D-printed vessels of various sizes in tandem with particle imaging to probe the dissipation effects on the particle motions. We have found that the liquid bath aspect ratio limits how much aggregation may occur for a particle-fluid density ratio greater than unity (e.g., $\rho_p/\rho_f >1$, where $\rho_p$ is the density of the particle and $\rho_f$ is the ambient fluid density.

Tea Leaf Paradox; Separations; Viscous effects; rotational flow; Dissipation

Engineering, Mechanical Engineering

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