Left: pebble stokes number St₁ as a function of radial distance. Right: corresponding particle size a_t. In this simulation, the temperature was scaled by ξ = 5, and the velocity fluctuations reduced by χ = 10. The line coloring corresponds to the simulation time according to the color bar. A darker color depicts the radial profile at a later time. The dashed lines indicate the value f_fSt_frag for each time. The horizontal dashed green line shows the limiting Stokes number St₁ = 10⁻² for planetesimal formation.