Ongoing research :

The objective of this study is to explore the dynamics of elastoviscoplastic droplets hitting the superhydrophobic surfaces. This might be associated with the applications in industrial droplet deposition processes such as ink-jet printing and the 3D printing of biomaterials. We hypothesize that the yield stress is expected to have the potential to suppress the droplet rebound on the surface and change the deposition regime. We are also interested in investigating how the combination of elastic stresses and capillary stresses changes the post-impact behaviour of the droplets and in particular the formation of the Worthington jet. We have been performing experiments and numerical simulations to decipher the effect of complex rheology of the material in terms of its elasticity and yield stress on this phenomenon.

Experimental setup

A schematic of the experimental setup is shown here. This includes a simple imaging system equipped with a high-speed camera, an injection device and a substrate controlled by a motorized stage. For the theoretical study of the problem, we use a multiphase flow solver Basilisk.

Some of our experimental results are showcased below,

Water drop on a super-hydrophobic surface-impact velocity increases from left to right

Carbopol drop on a super-hydrophobic surface

The research has been conducted in collaboration with FPInnovations, and Dr. Mehrnegar Mirvakili from FPInnovations’ material research group provided the superhydrophobic substrates.