Numerical study of the sedimentation of spheroidal particles

Journal article (2016)

Authors

Mehdi Niazi Ardekani KTH Royal Institute of Technology
P. Simões Costa Fluid Mechanics - Mechanical, Maritime and Materials Engineering
W.P. Breugem Multi Phase Systems - Mechanical, Maritime and Materials Engineering , Fluid Mechanics - Mechanical, Maritime and Materials Engineering
Luca Brandt KTH Royal Institute of Technology
Research Group
Multi Phase Systems (Mechanical, Maritime and Materials Engineering) (TU Delft)
Numerical modelling Sedimentation Non-spherical particles Drafting-kissing-tumbling Particle pair interactions
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Published Date

2016

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Multi Phase Systems

Abstract

The gravity-driven motion of rigid particles in a viscous fluid is relevant in many natural and industrial processes, yet this has mainly been investigated for spherical particles. We therefore consider the sedimentation of non-spherical (spheroidal) isolated and particle pairs in a viscous fluid via numerical simulations using the Immersed Boundary Method. The simulations performed here show that the critical Galileo number for the onset of secondary motions decreases as the spheroid aspect ratio departs from 1. Above this critical threshold, oblate particles perform a zigzagging motion whereas prolate particles rotate around the vertical axis while having their broad side facing the falling direction. Instabilities of the vortices in the wake follow when farther increasing the Galileo number. We also study the drafting-kissing-tumbling associated with the settling of particle pairs. We find that the interaction time increases significantly for non-spherical particles and, more interestingly, spheroidal particles are attracted from larger lateral displacements. This has important implications for the estimation of collision kernels and can result in increasing clustering in suspensions of sedimenting spheroids.