Evolution of a two-layer film with large viscosity ratio

This work focuses on developing a mathematical model that describes the evolution of two immiscible Newtonian liquid layers: the lower layer rests on a solid substrate and the upper layer rests on top of the lower layer. Our model assumes that the bottom liquid is more viscous than the top. Using the lubrication approximation scalings, we reduce the model into a system of two partial differential equations that describe the evolution of the liquid-liquid and liquid-gas interface over time. Numerical methods are used to gain insight into which conditions lead to dewetting/rupture of the film followed by a comparison of our work with existing models in literature.