Constriction Flow of Cellulose Laden Air-Aqueous Foam

Foams are encountered in everyday life across wide applications, e.g., in foods and cleaning products. They have also been widely used in different industries in processes such as flotation and oil recovery. The application of bio-based materials is a novel interest, and foam forming enables these materials to be used more flexibly. For efficient industrial usage, the flow of such materials must be well understood and characterized. This work measured the velocity field of nanocellulose laden foam in a two-dimensional Hele-Shaw cell with a constriction, using optical imaging and particle image velocimetry. The measurements showed that the addition of cellulose increased the effective viscosity of the liquid films. In a numerical simulation using the Giesekus polymer model, the experimental trend was reproduced through increasing the fluid's viscosity. Adding highly viscoelastic nanofibrillated cellulose suspension to foam affected only the viscous component of the foam. The delayed elastic response did not change.