  Using lattice Boltzmann simulations we study the hydrodynamics of an active
spherical particle near a no-slip wall. We develop a computational model for an
active Janus particle, by considering different and independent mobilities on
the two hemispheres and compare the behaviour to a standard squirmer model.We
show that the topology of the far-field hydrodynamic nature of the active Janus
particle is similar to the standard squirmer model, but in the near-field the
hydrodynamics differ. In order to study how the near-field effects affect the
interaction between the particle and a flat wall, we compare the behaviour of a
Janus swimmer and a squirmer near a no-slip surface via extensive numerical
simulations. Our results show generally a good agreement between these two
models, but they reveal some key differences especially with low magnitudes of
the squirming parameter $\beta$. Notably the affinity of the particles to be
trapped at a surface is increased for the active Janus particles when compared
to standard squirmers. Finally we find that when the particle is trapped on the
surface, the velocity parallel to the surface exceeds the bulk swimming speed
and scales linearly with $|\beta|$.
