  Large scale molecular dynamics simulations are used to study drying
suspensions of a binary mixture of large and small particles in explicit and
implicit solvents. The solvent is first modeled explicitly and then mapped to a
uniform viscous medium by matching the diffusion coefficients and the pair
correlation functions of the particles. `Small-on-top' stratification of the
particles, with an enrichment of the smaller ones at the receding liquid-vapor
interface during drying, is observed in both models under the same drying
conditions. With the implicit solvent model, we are able to model much thicker
films and study the effect of the initial film thickness on the final
distribution of particles in the dry film. Our results show that the degree of
stratification is controlled by the P\'{e}clet number defined using the initial
film thickness as the characteristic length scale. When the P\'{e}clet numbers
of large and small particles are much larger than 1, the degree of
`small-on-top' stratification is first enhanced and then weakens as the
P\'{e}clet numbers are increased.
