Upper panels: vertically-integrated radial mass flux of vapor. For three runs (passive,activeand active-nqL), the diffusive, advective and total vapor flux are plotted. The dotted lines denote zero-flux levels. The blue arrows indicate the position of the midplane snowline (r_snow,mid). The advective flux contributes significantly to the total vapor flux in theactivedisk runs (active and active-nqL), while it is negligible in the passive run. Lower panels: midplane gas radial velocity and the contributions from different terms following Equation (36). The thick grey line represents the measured value from the simulation. The T₂ term signifies the dominant contribution of the radial viscous stress to the radial velocity, while the contributions from radial advection (T₁ ) and ɀ-direction (T_ɀ) are negligible.