  We conduct numerical experiments to investigate the spatial clustering of
particles and bubbles in simulations of homogeneous and isotropic turbulence.
Varying the Stokes parameter and the densities, striking differences in the
clustering of the particles can be observed. To quantify these visual findings
we use the Kaplan--Yorke dimension. This local scaling analysis shows a
dimension of approximately 1.4 for the light bubble distribution, whereas the
distribution of very heavy particles shows a dimension of approximately 2.4.
However, clearly separate parameter combinations yield the same dimensions. To
overcome this degeneracy and to further develop the understanding of
clustering, we perform a morphological (geometrical and topological) analysis
of the particle distribution. For such an analysis, Minkowski functionals have
been successfully employed in cosmology, in order to quantify the global
geometry and topology of the large-scale distribution of galaxies. In the
context of dispersed multiphase flow, these Minkowski functionals -- being
morphological order parameters -- allow us to discern the filamentary structure
of the light particle distribution from the wall-like distribution of heavy
particles around empty interconnected tunnels.
