Top: mean size distribution in the 99^th percentile at different times. The dotted line indicates the size distribution at Ωt = 0. Bottom: same size distribution normalised by the background-size distribution σ⁰(τ_s). The dashed line indicates the Stokes number corresponding to the resonant velocity, and the dot-dashed line is the average Stokes number of the size distribution at Ωt = 0.