Ratio of dust Σ_d to gas surface density Σ_g (upper panels) and difference between azimuthal gas velocity υ_g,ϕ and Keplerian velocity υ_K (lower panels). Both quantities are depicted as a function of radius r and time t after the initialisation of the dust particles at t_d,init. The velocity difference is averaged over the vertical domain size, weighted by the dust mass, and expressed as a Mach number. In the absence of turbulence, this quantity is equal to the negative of the parameter Π as defined in Eq. (8). Black dots indicate that the azimuthal velocity is equal to or greater than the Keplerian velocity. Enhancements in the dust-to-gas surface density ratio and in the difference between azimuthal gas velocity and Keplerian velocity are larger at late times (t – t_d,init > 5 kyr) and small radii (r < 40 au) in SIwhileVSI than in the simulation of the streaming instability in isolation, and greatest at all times and radii in SIafterVSI. Surface density ratio and velocity difference can be seen to generally be correlated.