  We analyze the transport and deposition behavior of dilute microparticles in
turbulent Rayleigh-B\'enard convection. Two-dimensional direct numerical
simulations were carried out for the Rayleigh number ($Ra$) of $10^{8}$ and the
Prandtl number ($Pr$) of 0.71 (corresponding to the working fluids of air). The
Lagrangian point particle model was used to describe the motion of
microparticles in the turbulence. Our results show that the suspended particles
are homogeneously distributed in the turbulence for the Stokes number ($St$)
less than $10^{-3}$, and they tend to cluster into bands for $10^{-3} \lesssim
St \lesssim 10^{-2}$. At even larger $St$, the microparticles will quickly
sediment in the convection. We also calculate the mean-square displacement
(MSD) of the particle's trajectories. At short time intervals, the MSD exhibits
a ballistic regime, and it is isotropic in vertical and lateral directions; at
longer time intervals, the MSD reflects a confined motion for the particles,
and it is anisotropic in different directions. We further obtained a phase
diagram of the particle deposition positions on the wall, and we identified
three deposition states depending on the particle's density and diameter. An
interesting finding is that the dispersed particles preferred to deposit on the
vertical wall where the hot plumes arise, which is verified by tilting the cell
and altering the rotation direction of the large-scale circulation.
