As a disc moves through an oil-water interface, it entrains part of the oil into the water phase through a funnel-shaped volume. The shape of this volume is determined by a combination of potential flow and a starting vortex, but surprisingly, its shape remains independent of the disc velocity.
Read more about this in Physical Review Fluids: Volume entrained in the wake of a disc intruding into an oil-water interface, Ivo R. Peters, Matteo Madonia, Detlef Lohse, and Devaraj van der Meer Phys. Rev. Fluids 1, 033901 (2016)
A suspension of cornstarch particles in water is liquid-like when perturbed lightly, but turns into a jammed solid when sheared strongly. We explored how this solidification propagates through the material using high-speed imaging after applying a sudden deformation. This jamming transition is related to, but distinct from the shear-thickening that this material also exhibits.
Our findings are published in Nature:
I.R. Peters, S. Majumdar and H.M. Jaeger, Direct observation of dynamic shear jamming in dense suspensions, Nature (2016) DOI: 10.1038/nature17167