A Voronoï analysis of preferential concentration in a vertical channel flow

• Published in: Physics of fluids (1994) 2013-11, Vol.25 (11)
• Main Authors: Nilsen, Christopher, Andersson, Helge I, Zhao, Lihao
• Format: Article
• Language: English
• Subjects: Channel flow; Channels; Clustering; Computational fluid dynamics; Computer simulation; Direct numerical simulation; Drift; Fluid dynamics; Fluid flow; Gravitation; Physics; Reynolds number; Stokes number; Three dimensional analysis; Three dimensional flow
• ISSN: 1070-6631; 0031-9171; 1089-7666
• DOI: 10.1063/1.4830435

We use three-dimensional Voronoï analysis and results from a direct numerical simulation to study the preferential concentration of inertial particles in a vertical channel flow at Reynolds number 395. By comparing results in upward and downward flows with results from a channel flow without gravity, we are able to determine how gravity affects the particle clustering. Gravity increases the drift of particles towards the walls in an upward flow, while in the downward flow more particles are transported to the centre of the channel. For particles with Stokes number 100, the mean wall-normal particle velocity is positive in the entire core region. A significant increase in variance of the Voronoï probability distribution in the core region is observed in downward flow for Stokes numbers 30 and 100, indicating stronger particle clustering than in upward flow or flow without gravity. The increased clustering in the downward flow is believed to be partly caused by the reversed wall-normal drift assisting in bringing particles close together in the centre of the channel.