On Contact Lines of Newtonian, Viscoplastic, and Odd Fluids

Capillary ripples in thin films reflect the fluid’s response to surface tension and viscous forces. We study ripple formation in Newtonian, viscoplastic, and odd viscous fluids at the contact line of a droplet spreading on a prewetted surface. We report: (1) a critical capillary number for Newtonian fluids where the ripple wavelength diverges; (2) a threshold beyond which motion ceases in viscoplastic fluids; and (3) symmetry-broken ripples in odd fluids arising from nonreciprocal stresses. Our findings have implications for applications such as printing and highlight how rheology fundamentally alters interfacial dynamics.

Maziyar Jalaal received his Masters and PhD from UBC [PhD with Neil Balmforth & Boris Stoeber]. Postdoc 1 with Detlef Lohse at Uni Twente. Postdoc 2 with Ray Goldstein, Uni Cambridge. Assistant Prof. From 2021 and Associate Prof from 2024 - Uni Amsterdam. Research Interest: Fluid Mechanics, Active Matter, BioPhysics.