  Dynamics of a thin dewetting liquid film on a vertically oscillating
substrate is considered. We assume moderate vibration frequency and large
(compared to the mean film thickness) vibration amplitude. Using the
lubrication approximation and the averaging method, we formulate the coupled
sets of equations governing the pulsatile and the averaged fluid flows in the
film, and then derive the nonlinear amplitude equation for the averaged film
thickness. We show that there exists a window in the frequency-amplitude domain
where the parametric and shear-flow instabilities of the pulsatile flow do not
emerge. As a consequence, in this window the averaged description is reasonable
and the amplitude equation holds. The linear and nonlinear analyses of the
amplitude equation and the numerical computations show that such vibration
stabilizes the film against dewetting and rupture.
