Dust size distribution at 0.1, 1, and 3 Myr (from left to right), for the simulations with/without photoevaporation, and with/without dust traps. The solid lines indicate the estimated fragmentation and drift growth limits (magenta and cyan, respectively). For reference, we show the grain sizes that correspond to St = 0.1 with a dashed white line, and the photoevaporation radius with a dashed red line. Note that we plot σ_dust, which has surface density units, but it is normalized by the logarithmic bin size (see Birnstiel et al. 2010).