Reynolds number dependence of heavy particles clustering in homogeneous isotropic turbulence

Abstract

In homogeneous isotropic turbulence, the degree of heavy particle clustering is reduced with increasing Taylor Reynolds number (${R}_{\ensuremath{\lambda}}$) for 52 \ensuremath{\le} ${R}_{\ensuremath{\lambda}}$ \ensuremath{\le} 139 when the Stokes number (St) is small. Contrarily, the clustering of high-St particles tends to stegthen with increasing ${R}_{\ensuremath{\lambda}}$. Quantities invoked for low-St particle clustering include both the strength of and characteristic time of particle trapping by ``shear structures'' quantified by the second invariant of the velocity gradient tensor. The enhancement of high-St particle clustering results from the increasing large-scale eddies at higher ${R}_{\ensuremath{\lambda}}$.