Dust density at t = 100Ω⁻¹ for three different species, τ_s = 0.00124, 0.01, and 0.08 (left to right) for the polydisperse run poly5 (top panels) and the three corresponding monodisperse runs (bottom panels). Note that the colour bar limits are fixed for the same τ_s (top and bottom panels), but the maximum value increases by an order of magnitude as τ_s increases (left to right)