Statistics of particle dispersion in direct numerical simulations of wall-bounded turbulence: Results of an international collaborative benchmark test

Abstract

a b s t r a c tIn this paper the results of an international collaborative test case relative to the production of a direct numerical simulation and Lagrangian particle tracking database for turbulent particle dispersion in channel flow at low Reynolds number are presented. The objective of this test case is to establish a homogeneous source of data relevant to the general problem of particle dispersion in wall-bounded turbulence. Different numerical approaches and computational codes have been used to simulate the particle-laden flow and calculations have been carried on long enough to achieve a statistically steady condition for particle distribution. In such stationary regime, a comprehensive database including both post-processed statistics and raw data for the fluid and for the particles has been obtained. The complete datasets can be downloaded from the web at HTTP://CFD.CINECA.IT/CFD/REPOSITORY/. In this paper the most relevant velocity statistics (for both phases) and particle distribution statistics are discussed and benchmarked by direct comparison between the different numerical predictions.

Anisotropy in pair dispersion of inertial particles in turbulent channel flow

“…The timestep for tracking heavy particles is δt + = 0.45, corresponding to about one tenth of the non-dimensional response time of the smallest particle tracked (d p = 45.6 μm, see Table I) and ensuring adequate description of particle dynamics. 43 Periodic boundary conditions are imposed on particles moving outside the computational domain in the homogeneous directions. Perfectly elastic collisions at the smooth walls are assumed when the particle center is at a distance lower than one particle radius from the wall.…”

“…Results presented in this paper are relative to a value of the shear Reynolds number Flow field data are taken from the same repository used for the benchmark test described in Marchioli et al 43 Samples of n p = 4.2 × 10 6 particles characterized by different response times were considered. The response time is made dimensionless using wall variables, and the Stokes number is thus obtained…”

Four-way coupled simulations of small particles in turbulent channel flow: The effects of particle shape and Stokes number

“…In these gas-solid flows, complex interactions between dispersed particles and fluid flows make the phenomena of dispersed two-phase flows much more complex than singlephase flows. In the literature, gas-solid wall-bounded flows have been extensively studied experimentally [1][2][3][4] and numerically [5][6][7] . Most of these research papers investigated flows with spherical particles.…”

“…Among these approaches, the Lagrangian point-particle approach developed by Crowe, Sharma, and Stock 16 has been extensively applied 6,[17][18][19][20] , and also used in this study. In this approach, solid particles are tracked individually, and their properties, such as position, mass momentum and energy of individual particle, are determined by Newton's second law.…”

Preferential concentration of inertial fibres in a turbulent channel flow

“…In situations where physical, chemical or biological interaction between particles is required, such inhomogeneities affect the probability of finding particles close to one another which influences their collision probability, or biological, chemical or gravitational interaction. This phenomena is still not understood for non-spherical and even spherical particles; there is therefore a need to further study the nature and dynamics of these inhomogeneities and their association with fluid turbulence structures [3].…”