Dust heightscale H_d as a function of the Stokes number for three different plasma β. The diamond markers correspond to direct measurement from numerical simulations, with the definition given by Eq. (25). The dotted curves are derived from a simple diffusion model assuming that gravitational settling is balanced by homogenous turbulent diffusion (see Dubrulle et al. 1995; Fromang & Papaloizou 2006, and Sect. 5). The dashed/red horizontal line denotes the size of the numerical cells.