Statistical models for predicting pair dispersion and particle clustering in isotropic turbulence and their applications

Anisotropy in pair dispersion of inertial particles in turbulent channel flow

“…Statistical characterization of pair dispersion dynamics is of fundamental importance for transport processes in turbulence, particularly those involving mixing of liquids and gasses, since relative separation of pairs is intimately connected to local concentration fluctuations. 56 Because of this connection, the present study is also useful as benchmark for validation of two-point models 17 for predicting the relative velocity distribution of particle pairs in wall-bounded flows. Development of these models will be particularly useful to advance Eulerian approaches to large-eddy simulation (LES) of particle transport in turbulent flows.…”

“…14 Of the many studies dealing with two-particle dispersion, most focus on the behavior of fluid tracers, 9,15,16 and consider flows where large-scale shear effects are not present. [16][17][18] The objective of this paper is to provide a statistical characterization of pair dispersion for the more complicated case of inertial particles in turbulent shear flow. Compared to the case of 073305-2 Pitton et al Phys.…”

“…This phenomenology has been demonstrated and discussed in many experimental works, 2,20 as well as numerical studies [21][22][23][24][25][26][27][28] and theoretical analyses. 17,[29][30][31] From a modelling standpoint, reproducing accurately pair relative velocity and dispersion statistics is crucial to predict the effect of particle clustering on turbulent collisions and sedimentation. 17 In a series of recent papers, 32,33 Bec and co-workers characterized the relative dispersion of heavy point particles in homogeneous isotropic turbulence, focusing specifically on the scaling of particle velocity distribution at changing the degree of inertia in the different dispersive regimes (dissipative, inertial, and diffusive).…”

“…17,[29][30][31] From a modelling standpoint, reproducing accurately pair relative velocity and dispersion statistics is crucial to predict the effect of particle clustering on turbulent collisions and sedimentation. 17 In a series of recent papers, 32,33 Bec and co-workers characterized the relative dispersion of heavy point particles in homogeneous isotropic turbulence, focusing specifically on the scaling of particle velocity distribution at changing the degree of inertia in the different dispersive regimes (dissipative, inertial, and diffusive). A further complication is the presence of shear, which stretches the distance between particles and is expected to induce strong deviations from the usual diffusion laws.…”

“…By doing so, we will find different time evolution for d(t) which depends on the properties of the particles (inertia, in particular) but also on flow characteristics-local mean shear, turbulent fluctuations and Lagrangian time scales-experienced by paired particles during the first stages of their motion. To our knowledge, there is no such database available for bounded flows: statistics presented in this paper might be particularly useful for validation of two-point Eulerian models, which are currently limited to homogeneous isotropic turbulence, 9,17 and for improving current physical understanding of multiple particle dispersion. 38 The paper is organized as follows.…”