2D histograms of the dust-ratio variations as a function of gas density for the fiducial model 256MRN. The top-left panel shows the variation in total dust-to-gas ratio ɛ, while the other panels show the dust-ratio variations of each dust species. The colour coding indicates the mass of the gas in log scale (in solar units). The horizontal grey dotted line separates the dust-enriched and dust-depleted regions. The vertical line indicates St = 1 (solid) for each dust species. All quantities are averaged over more than one dynamical time t_cross and the variations are normalised to the initial value of each dust ratio.