Abstract
Abstract – We study a new paradigm for ultrasonic-driven object coating by using a model system where MHz-level surface acoustic waves (SAWs) drive the spreading of a silicone oil film atop topographical obstacles. We use experiments to show that nanometre-amplitude SAWs, propagating in the substrate of a piezoelectric actuator, propel macroscopic oil films to climb and traverse solid obstacles placed on the actuator. The oil dynamics reveal rich coupling between ultrasonic forcing, capillarity and gravity, the balance of which determines coating. In addition to the experiment, we formulate a simplified two-dimensional theoretical model that incorporates obstacle geometry directly in the oil thin-film evolution equation, introducing a new representation of acoustic streaming in the presence of substrate height variations. Despite the simplifications inherent in the modelling, simulations show qualitative agreement with experiments, providing evidence that the model captures the key physics of the coating flows observed.
| Original language | English (US) |
|---|---|
| Article number | 20260147 |
| Journal | Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences |
| Volume | 482 |
| Issue number | 2345 |
| DOIs | |
| State | Published - Sep 9 2026 |
ASJC Scopus subject areas
- General Mathematics
- General Engineering
- General Physics and Astronomy
Keywords
- acoustics
- lubrication theory
- thin films
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