Dosa (dosae in Kannada) is one of the most relished dishes in India. An important prerequisite to prepare a good dosa is a hot pan, usually called as tawa.
Usually, just before the dosa batter is spread on the tawa, a few drops of water is sprinkled on this heated surface.
The video shows the dynamics of water droplets on a heated tawa at around 800 frames per second. Notice how the droplet expands, oscillates and evaporate….all at a very fast pace
Interestingly such fluid dynamics and oscillations can also be realized by heating a metal surface with a laser beam, which we do do in my lab. Of course, in such a situation, the laser heating is more localised and dynamics of the fluid is more complex, and importantly one can trap and optically manipulate colloids, nanoparticles and molecules, in such environments. More on this in a future blog..