Vertical profiles of the flux terms appearing in the right-hand side of Eq. (31), calculated directly form simulations and averaged in time, for β = 10⁴ and three different Stokes numbers. From left to right: St = 0.0025, 0.001 and 0.00025. Green, blue and red lines account respectively for the turbulent correlation term, mean wind and mean drift. The brown dashed line is the mean drift due to gravitational settling estimated in the terminal velocity approximation and assuming that (small gas density fluctuations).