Oil droplets dispersed on a water surface reveal interfacial tension effects and thin-film flow under direct side-lighting.

This image captures the interaction between oil droplets and a water surface, illuminated with angled light to emphasize variations in thickness and surface tension effects. The different droplet sizes, circular footprints, and clustering patterns result from the immiscibility of oil in water and the dominance of interfacial tension at this scale. Small droplets remain spherical due to high surface-area-to-volume ratio, while larger droplets flatten into disks as gravity begins to overcome cohesive forces. The speckled texture and haloing around droplets reveal Marangoni stresses and micro-scale currents in the surrounding fluid, which redistribute the oil into distinct patches across the surface.

https://www.flowvis.org/wp-content/uploads/2025/12/Team-Second-Report-HANSEN.pdf