  The lift and drag forces acting on a small, neutrally-buoyant spherical
particle in a single-wall-bounded linear shear flow are examined via numerical
computation. The effects of shear rate are isolated from those of slip by
setting the particle velocity equal to the local fluid velocity (zero slip),
and examining the resulting hydrodynamic forces as a function of separation
distance. In contrast to much of the previous numerical literature, low shear
Reynolds numbers are considered ($10^{-3} \lesssim Re_{\gamma} \lesssim
10^{-1}$). This shear rate range is relevant when dealing with particulate
flows within small channels, for example particle migration in microfluidic
devices being used or developed for the biotech industry. We demonstrate a
strong dependence of both the lift and drag forces on shear rate. Building on
previous theoretical $Re_{\gamma} \ll 1$ studies, a wall-shear based lift
correlation is proposed that is applicable when the wall lies both within the
inner and outer regions of the disturbed flow. Similarly, we validate an
improved drag correlation that includes higher order terms in wall separation
distance that more accurately captures the drag force when the particle is
close to, but not touching, the wall. Application of the new correlations shows
that the examined shear based lift force is as important as the previously
examined slip based lift force, highlighting the need to account for shear when
predicting the near-wall movement of neutrally-buoyant particles.
