Rodolfo Brandão, University of British Columbia

Title: Retraction Dynamics of Thin Viscoelastic Filaments

Abstract

We investigate the capillary-driven retraction of a slender cylindrical liquid filament of an Oldroyd-B fluid in the low-Reynolds-number regime, where inertia is negligible. In this regime, the fluid domain naturally decomposes into two regions: a thin-film region described by uniaxial extensional flow, and a localized tip region governed by the full Stokes equations for a viscoelastic fluid. Asymptotic matching between these regions yields an effective boundary condition for the thin-film dynamics, capturing the balance between viscous and capillary forces at the retracting tip. From that, we derive a reduced model for the filament retraction speed in the form of a system of ordinary differential equations. Finally, we discuss how these asymptotic ideas can be extended to describe the dynamics of growing holes in ruptured viscoelastic films.