  Tom et al.\ (J.\ Fluid Mech.\ 947, A7, 2022) investigated the impact of
two-way coupling (2WC) on particle settling in turbulence. For the limited
parameter choices explored, it was found that 2WC substantially enhances
particle settling compared to the one-way coupled (1WC) case, even at low mass
loading $\Phi_m$. Moreover, contrary to previous claims, it was demonstrated
that preferential sweeping remains the mechanism responsible for the particles
settling faster than the Stokes settling velocity in 2WC flows. However,
crucial questions remain: 1) how small must $\Phi_m$ be for the effects of 2WC
on particle settling to be negligible? 2) does the preferential sweeping
mechanism remain relevant in 2WC flows as $\Phi_m$ is increased? To answer
these, we explore a much broader portion of the parameter space, and our
simulations cover cases where the impact of 2WC on the global fluid statistics
ranges from negligible to strong. We find that even for $\Phi_m=7.5\times
10^{-3}$, 2WC can noticeably increase the settling for some choices of the
Stokes and Froude numbers. We also demonstrate that even when $\Phi_m$ is large
enough for the global fluid statistics to be strongly affected by the
particles, preferential sweeping is still the mechanism responsible for the
enhanced particle settling. The difference between the 1WC and 2WC cases is
that, in the latter the particles are not merely swept around the
downward-moving side of vortices, but they also drag the fluid with them as
they move down.
