  Direct numerical simulation of homogeneous isotropic turbulence shows
pronounced clustering of inertial particles in the inertial subrange at high
Reynolds number, in addition to the clustering typically observed in the near
dissipation range. The clustering in the inertial subrange is characterized by
the bump in the particle number density spectra and is due to modulation of
preferential concentration. The number density spectrum can be modeled by a
rational function of the scale-dependent Stokes number.
