Creating surfaces that can resist fouling, reduce drag, or regulate heat transfer in unsteady fluid flows is a major scientific and technological challenge. Yet, nature provides remarkable examples of how this can be achieved. Many plants and animals have evolved slippery surfaces by combining microstructured textures with a lubricating layer of gas, liquid, or mucus. These biological surfaces play a vital role in controlling the exchange of energy, mass, and momentum between the organism and the surrounding flow.
Inspired by these natural systems, researchers have designed lubricant-infused surfaces (LIS)—microstructured materials that lock in place a thin layer of lubricant. Under ideal laboratory conditions, LIS can display extraordinary properties: they resist fouling, reduce frictional drag, enhance heat transfer, and can even host or release small amounts of liquid for actuation. However, in real environments, the behaviour of the lubricant becomes highly unpredictable. Turbulence, surfactants (surface-active molecules), and microorganisms such as bacteria interact with the lubricant layer, often destroying its functionality. As a result, synthetic slippery surfaces that can survive realistic submerged flow conditions for extensive periods of time have not yet been realised.
The LUBFLOW project addresses this challenge by providing a fundamental understanding of how lubricants behave under harsh flow conditions. The goal is to uncover the physical principles that govern surface-confined liquid-liquid interfaces in the presence of turbulence, surfactants, and biological activity.
Predicting the complex behavior of the lubricant is, however, a considerable scientific challenge due to the tiny length scales of liquid-liquid interfaces, the large scales of flow patterns, the existence of “hidden” surface-active particles and the active decisions taken by settling bacteria. Recent advances in high-resolution imaging and direct numerical simulations (DNS) make it possible to study these multiscale interactions in detail. LUBFLOW combines these experimental and computational techniques to explore both the fundamental physics and potential new functions of submerged lubricant-infused surfaces.
The specific objectives of LUBFLOW are:
1. To characterise the behaviour of submerged lubricant-infused surfaces in the presence of shear flows, surfactants, and biofilms, using advanced imaging and numerical simulations.
2. To exploit new functions of these surfaces for particle control, surface actuation, and thermocapillary-driven transport.
By tackling these objectives, LUBFLOW contributes to a deeper understanding of how liquid-liquid interfaces behave in complex environments and how they can be engineered to remain stable and functional.
