  The aim of this work is to construct an algorithm for visualizing a
polydisperse phase of solid particles (dust) in an inhomogeneous flow of a
two-phase gas-dust mixture that would allow us to see, within one plot, the
degree of polydispersity of the dust phase and the difference in the spatial
distributions of individual fractions of dust particles in the computational
domain. The developed technique allows us to reproduce concentrations from one
to three fractions of dust particles in each cell in the computational domain.
Each of the three fractions of dust particles is mapped to one of the main
channels of the RGB palette. The intensity of the color shade is set to be
proportional to the relative concentration of dust particles in this fraction.
The final image for a polydisperse mixture is obtained by adding images in each
of the three color channels. To visualize the degree of polydispersity, I
propose depicting the spatial distribution of the entropy of the dust mixture.
The definition of the entropy of a mixture is generalized to take into account
the states of a mixture with zero number of particles in the mixture. They
correspond to dust-free sections of the computational domain (voids). The
proposed method for visualizing the polydispersity of a mixture of particles is
demonstrated using the example of dynamic numerical modeling of the spatial
features of dust structures formed in turbulent gas-dust flows and in flows
with shock waves.
