Séminaire de Mécanique d'Orsay

Le Jeudi 15 janvier à 14h00 - Salle de conférences du FAST

Tuning macroscopic fluid behavior using micro-structures

Émilie Dressaire
New York University

In this talk, I will present experiments devoted to systems in which the presence of micrometer-scale structures has macroscopic, observable effects on the fluid. We will first consider thin liquid films formed when jets impinge on solid surfaces such as hydraulic jumps and water bells. On a smooth surface, the flow is radial and isotropic. The addition of a controlled micro-patterned surface allows tuning of the geometry of the flow into polygonal water structures. We will then discuss the wetting and drying of liquid between two randomly oriented fibers whose diameters are a few hundreds of micrometers. We show the influence of the volume and the tilting angle between the fibers on the morphology of the liquid at the node of the fibers and its drying dynamics. We will then focus on particle-laden flow in micro-channels. Those channels are used as a pore-scale model of porous membranes or filters that allow fluid to pass through but trap contaminants. Once a clog is formed in a pore, incoming particles aggregate upstream, which leads to a dramatic reduction of the flow rate. We use this microfluidic approach to study the clog formation and the growth of the aggregate.
Figure: From left to right: a polygonal hydraulic jump, morphologies adopted by a fluid on crossed fibers and clogs in parallel micro-channels