Soft matter lubrication
Friction between sliding surfaces has a great economic and environmental cost, with it leading to a third of a car’s fuel use and wasting 23% of global energy production. This has spurred development of highly loaded contacts with liquid lubricants. Lightly loaded surfaces, with a thick liquid film are considered inefficient, and even trivial. This situation is common in soft matter, from swallowing food, or applying skin cream, to ceramic extrusion and even in synovial joints. However, there are additional complexities such as texture (tongue papillae), a non-Newtonian fluid (skin cream), deformability or a combination of sliding and squeezing.
In this talk, I will explore how scaling theories, alongside experiments, can disentangle soft matter lubrication. For a textured surface, the delicate balance between shear and pressure-driven flows is highlighted, while squeeze flow beneath a flexible surface isolates the coupling between pressure-driven flow and deformation. Finally, I will touch upon how such approaches lead to the design of optimised non-Newtonian fluids.
