The science of droplet formation

A jet of glycerol 50 % v/v (aqueous solution) breaking into droplets. The solution is dyed green. (Credit: Bill Hammack)

A smooth jet of water coming out of a slightly open kitchen faucet and breaking into droplets is a familiar experience. The droplet formation happens at a certain distance from the faucet. Why does a water jet break into droplets? Why can’t it just stay as it is? Bill Hammack (EngineerGuy) has an excellent video on this phenomenon (I highly recommend watching it). In this post, I will try to explain the formation of droplets from a liquid jet using a little mathematics.

Figure 1 shows a schematic of a liquid jet emerging through a small exit. The undulations form…


How to not let it manipulate me

Image by Marc Schäfer from Pixabay.

Instance 1:

“You do not post much on Facebook. Are you sad?” he said casually. I was taken aback by this question. My happiness was being correlated with my presence on social media.

Instance 2:

“I unliked all his photos because he doesn’t like my photos. I will never like his posts anymore,” she said. A mere ‘like’, ‘unlike’, or ‘follow’ was so important that its presence/absence was enough to create animosity between these two friends.

Such instances are not at all uncommon these days. But, this was the first time I experienced the adverse effect of social media myself…


Why some droplets are spherical while the others are not

Photo by Jos Speetjens on Unsplash

A dripping faucet in a kitchen is an ordinary-looking everyday thing. A thread of water emerges from the faucet and forms a droplet. Sometimes, the thread is big enough that it breaks into a series of droplets. The formation of droplets from a jet/thread of water is very rich in physics and absolutely beautiful (I encourage you to look at high-speed footage of similar phenomena here). These droplets are of different sizes and shapes. They are not always spherical (Fig. 1).

Raindrops form in clouds. As they fall, they coalesce and form bigger droplets. These bigger droplets then disintegrate into…


How ‘vector interpretation’ of Kepler’s second law hints at the presence of gravitational force between the Sun and a planet

Image by mdherren from Pixabay.

Johannes Kepler, the German mathematician and astronomer, is one of the most famous names in astronomy. Kepler formulated three laws of planetary motion based on the precise, detailed and meticulously recorded observations of planetary motion and stars by the great Danish astronomer Tycho Brahe (who collected astronomical data without the aid of a telescope). Kepler worked as an assistant to Tycho Brahe. It took him around 20 years to arrive at the laws of planetary motion. These laws can be stated as follows (source: Wikipedia):

  1. The orbit of a planet is an ellipse with the Sun at one of the…


The science behind a counter-intuitive everyday observation

Photo by Toa Heftiba on Unsplash

In our daily lives, so many things happen around us, which look quite ordinary. Some are human-made, and some are natural. We do not see anything surprising in them as they are a part of our daily routine. But, if we think about them for a bit and wonder why a particular thing happens in the way it happens, we will be surprised to know the beautiful explanations science offers. Many times, the science behind ordinary things in our lives also governs some of the biggest human-made and natural phenomena. …


The Science of Liquid Droplets

Photo by Miguel Luis on Unsplash

Ever wondered what happens to a raindrop during its journey from clouds to the ground? It does not stay intact. It deforms and breaks as it comes down. According to Villermaux and Bossa, the raindrop flattens as it comes down and forms a bag-like structure before it breaks (I strongly recommend watching the supplementary movie on this page for the high-definition video).

Why does a Liquid Droplet Break?

A liquid droplet assumes a spherical shape because of surface tension. The force of surface tension tries to minimize the surface area of a liquid droplet for a given volume. Since a sphere has a minimum surface area…


Photo by Martin Brechtl on Unsplash

Do you think the raindrops we receive at the ground have the same size during their entire journey? No. They form in the clouds. They coalesce as they come down and form bigger droplets. These bigger droplets then disintegrate (anatomy of a raindrop). Villermaux and Bossa believe that the raindrop disintegration happens through this beautiful mechanism (for the high-definition video, I highly recommend watching this supplementary movie). Initially, the droplet deforms/flattens, and then, it disintegrates into smaller droplets. These smaller droplets are the ones which we receive at the ground. These smaller droplets do not undergo further disintegration before they…

Sumit Joshi

PhD student, IIT Madras, India | https://in.linkedin.com/in/sumit-joshi-67738063

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