Interfacial Dynamics of Thin Viscoelastic Films and Drops

TL;DR

This study computationally explores how viscoelastic properties influence the behavior of thin films and drops on substrates, revealing effects on droplet formation, spreading, and retraction consistent with experiments.

Contribution

It introduces a long-wave model incorporating Jeffreys viscoelastic stresses to analyze interfacial dynamics of thin films and drops, highlighting the impact of elasticity and slippage.

Findings

Higher elasticity leads to multiple secondary droplets during dewetting.

Elastic effects cause deviations from Cox-Voinov law in spreading.

Elasticity enhances spreading and suppresses retraction.

Abstract

We present a computational investigation of thin viscoelastic films and drops on a solid substrate subject to the van der Waals interaction force, in two spatial dimensions. The governing equations are obtained within a long-wave approximation of the Navier-Stokes equations with Jeffreys model for viscoelastic stresses. We investigate the effects of viscoelasticity, Newtonian viscosity, and the substrate slippage on the dynamics of thin viscoelastic films. We also study the effects of viscoelasticity on drops that spread or recede on a prewetted substrate. For dewetting films, the numerical results show the presence of multiple secondary droplets for higher values of elasticity, consistently with experimental findings. For drops, we find that elastic effects lead to deviations from the Cox-Voinov law for partially wetting fluids. In general, elastic effects enhance spreading, and suppress retraction, compared to Newtonian ones.