Summary: Cover page showing interferometry imaging revealing patterns of double-diffusion emerging on the cap of a salt water surface bubble, followed by formation of salt crystals eventually falling from the top to the foot of the cap as evaporation takes place.
Study: In our recent study published in 2018 in this issue, we show how evaporation enhances the lifetime of bubbles even without addition of surfactants. We quantify this process, model it, and give an illustration of the process in an analog experiment with salt shows that we can even end up with crystals of salts nucleating at the top of the bubble (illustrating the increase of concentration at the top). The crystals once formed, slide down the cap.
For more, see Poulain, S., Villermaux, E., and Bourouiba, L. (2018) Ageing and burst of surface bubbles. Journal of Fluid Mechanics. 851: 636-671. Selected for volume cover page: PDF.
For more on this research track here.