KIVI Hoogendoorn Fluid Mechanics Award 2023
It is great pleasure to announce that the recipient of the KIVI Hoogendoorn Fluid Mechanics Award for the best PhD thesis defended in the academic year 2022-2023 is:
Dr. Vatsal Sanjay
He defended his PhD thesis (with Cum Laude distinction) on 15th July 2022 at the University of Twente, with promotor prof. Detlef Lohse. The thesis is entitled: “Viscous Free-Surface Flows”. The Award Ceremony will take place at the upcoming Burgers Symposium on 29 – 30 May 2024 in Lunteren, where the recipient will also give a presentation on his thesis work.
This thesis investigates several free-surface phenomena to illustrate the role of viscous stresses. The study includes the impact of spherical liquid drops on non-wetting substrates, with a focus on capillary-driven retraction of films and bursting of free-surface bubbles. The main numerical method employed is the volume of fluid method.
The numerical simulations elaborated upon the energetics of each of the processes and demystified the role of viscous dissipation. Even in the inertial limit, viscous dissipation still accounts for almost 50% of the released energy during both classical and generalized Taylor-Culick retractions. Similarly, for drop impact processes, again in the inertial limit, viscous dissipation can amount to almost 20% of the initial energy. An example on the small scale is drop-film interactions in the inkjet printing process and one on the large scale late-time spreading during oil spillage.
The three-fluid model developed in this thesis is particularly useful when it is thermodynamically favorable for one of the fluids to spread over another one. Indeed, further extending the methods of this thesis to generalized three-phase contact line motions is expected to yield interesting results. A very interesting and highly relevant perspective is that the current three-fluid model can also handle different surface tension forces for the three interfaces. It can thus be used as a base model to incorporate multi-physical aspects, such as Marangoni flows and multicomponent systems.