Yield-stress fluids foams: flow patterns and controlled production in T-junction and flow-focusing devices

Benoit Laborie (1) , Florence Rouyer (2) , Dan Angelescu (3) , Elise Lorenceau (2)

1 navier umr 8205 - Laboratoire Navier
2 Rhéophysique
3 ESYCOM - Electronique, Systèmes de communication et Microsystèmes

We study the formation of yield-stress fluid foams in millifluidic flow-focusing and T-junction devices. First, we provide a phase diagram for the unsteady operating regimes of bubble production when the gas pressure and the yield-stress fluid flow rate are imposed. Three regimes are identified: a co-flow of gas and yield-stress fluid, a transient production of bubble and a flow of yield-stress fluid only. Taking wall slip into account, we provide a model for the pressure at the onset of bubble formation. Then, we detail and compare two simple methods to ensure steady bubble production: regulation of the gas pressure or flow-rate. These techniques, which are easy to implement, thus open pathways for controlled production of dry yield-stress fluid foams as shown at the end of this article.

Domaines: Dynamique des Fluides [physics.flu-dyn]; Matière Molle [cond-mat.soft]

Benoit Laborie, Florence Rouyer, Dan Angelescu, Elise Lorenceau. Yield-stress fluids foams: flow patterns and controlled production in T-junction and flow-focusing devices. Soft Matter, 2016, 12 (46), pp.9355 - 9363. ⟨10.1039/c6sm02054b⟩. ⟨hal-01691667⟩