Quantification of preferential concentration of colliding particles in a homogeneous isotropic turbulent flow

This paper addresses the effect of inter-particle collisions on the segregation of non-settling inertial particles in homogeneous isotropic turbulence. For this purpose, direct numerical simulations of particles in statistically steady homogeneous isotropic turbulence have been performed by the lattice Boltzmann method considering inter-particle collisions. The preferential concentration of suspended particles is quantified using several clustering measures: segregation parameter, correlation dimension, radial distribution function, Voronoi diagrams and the topological tool of Minkowski functionals. Effects of particle inertia, inter-particle collisions and increasing volume fraction in the aforementioned measures are discussed. The obtained results show that collisions between particles have a remarkable influence on the formation of clusters. In particular, under locally dilute conditions, increasing particle volume fraction implies a moderate clustering intensification, but for locally dense conditions an increase of the mean inter-particle distance inside clusters can be envisaged as a consequence of the re-dispersing effect of inter-particle collisions. (C) 2019 Elsevier Ltd. All rights reserved.