  When an aqueous drop contacts an immiscible oil film, it displays complex
interfacial dynamics. Upon contact the oil spreads onto the drop's liquid-air
interface, first forming a curvature that drives an apparent drop spreading
motion and later fully engulfing the drop. We study this flow using both
3-phase Lattice-Boltzmann simulations based on the conservative phase field
model and experiments. Inertially and viscously limited dynamics are explored
using the Ohnesorge number $Oh$ as a function of $R/H$, the ratio between the
initial drop radius $R$ and the film height $H$. Both regimes show that the
apparent spreading radius $r$ is fairly independent of the film height, and
scales with time $T$ as $r\sim T^{1/2}$ for $Oh\ll 1$ and for $Oh\gg 1$ as
$r\sim T^{2/5}$. For $Oh\gg 1$ we show experimentally that this immiscible
apparent spreading motion is analogous with the miscible drop-film coalescence
case. Contrary to the apparent spreading, however, we find that the late time
engulfment dynamics and final interface profiles are significantly affected by
the ratio of $H/R$.
