Séminaire IUSTI – 23 juin 2023 – 11h salle 250

The fluid dynamics of raindrop impacts on plant leaves

Tristan Gilet – Université de Liège, Belgique

The interception of raindrops by plant leaves induces a redistribution of water, nutrients, and micro-organisms, from the surface of these leaves to their surroundings. It consequently shapes the plant ecosystem. For example, in wheat fields (as in most major crops), splashing raindrops are the main mechanism of dispersal of fungal diseases at the epidemic stage, with severe consequences on crop yield. From a fluid dynamics point of view, there is a wealth of scenarios through which raindrops can be intercepted, depending on the type of rain and on leaf properties (geometry, elasticity, initial wetting state). In this talk, I will discuss four dominant scenarios of raindrop impacts on plant leaves: (i) impacts near the edges of a dry leaf, (ii) impacts next to sessile drops of residual water, (iii) impacts on thin films of residual water at the leaf surface, and (iv) impacts on small and compliant leaves. I will share our progress on describing the liquid break-up mechanism corresponding to each scenario and quantifying it as a function of drop and leaf physical properties.