Séminaire Manon Lestimé (LadHyx)

Coalescence: From the Merging of Complex Fluid Droplets to Thin Film Instability

Coalescence phenomena play a key role in many practical systems, from industrial applications like inkjet printing to biological processes. In this seminar, I will explore two situations of coalescence. In the first part, the merging of two freely suspended droplets of a jammed yield-stress fluid is investigated. While coalescence of fluids with shear-thinning behavior and viscoelasticity has been studied, relating the dynamics to the rheology and elasticity remains to be fully understood. We examine the time evolution and shape of the neck formed between merging droplets to better understand the impact of rheology on the coalescence process. The second part focuses on the coalescence of two thin films of a viscous Newtonian liquid. Under certain conditions, the merging of the films leads to the destabilization of the interface, resulting in the formation of finger-like patterns. We investigate the mechanisms underlying this instability and model its geometrical features using scaling laws.