Spreading of a solid-on-solid drop

We study the spreading of the foot of a two-dimensional drop via Monte Carlo simulations without conservation law. The profile, or height of the spreading phase as a function of the distance from the initial drop, is described by a solid-on-solid model. For positive spreading coefficients, we find a precursor film extending linearly with time, and thickening as ${\mathit{t}}^{1/4}$ due to entropic repulsion. For a vanishing spreading coefficient, i.e., at the wetting transition, the foot of the profile is found to scale as ${\mathit{t}}^{1/2}$ parallel and perpendicular to the substrate, with no precursor asymptote. For partial wetting, relaxation is checked against exact results including finite-size effects.