Sharp Well-Posedness and Parameter Asymptotics for a Nonlocal Model of Thin Film Flows

TL;DR

This paper establishes the sharp well-posedness of a nonlocal thin film flow model in Sobolev spaces and analyzes how solutions behave asymptotically as physical parameters change, connecting different flow regimes.

Contribution

It proves the well-posedness threshold in Sobolev spaces and rigorously analyzes the asymptotic limits of the model with respect to electric field effects and inclination angle.

Findings

Well-posedness for s > -2 in Sobolev spaces

Ill-posedness for s < -2

Convergence of the model to vertical plane flow as electric effects vanish

Abstract

This work focuses on the mathematical analysis of the Cauchy problem associated with a two-dimensional equation describing the dynamics of a thin fluid film flowing down an inclined flat plate under the influence of gravity and an electric field. As a first objective, we study the sharp global well-posedness of solutions within the framework of Sobolev spaces. Specifically, we show that the equation is well-posed in $H^s(\mathbb{R}^2)$ for $s>-2$, and ill-posed for $s<-2$. Our main contribution is to investigate the asymptotic behavior of solutions with respect to the physical parameters of the model. This behavior is not only of mathematical interest but also of physical relevance. We rigorously show that, as the effects of the electric field vanish and the inclination angle increases, the model converges to a related one describing thin film flow down a vertical plane.