“Aerosolized microorganisms may play an important role in climate change, disease transmission, water and soil contaminants, and geographic migration of microbes. While it is known that bioaerosols are generated when bubbles break on the surface of water containing microbes, it is largely unclear how viable soil-based microbes are transferred to the atmosphere. Here we report a previously unknown mechanism by which rain disperses soil bacteria into the air. Bubbles, tens of micrometres in size, formed inside the raindrops disperse micro-droplets containing soil bacteria during raindrop impingement. A single raindrop can transfer 0.01% of bacteria on the soil surface and the bacteria can survive more than one hour after the aerosol generation process. This work further reveals that bacteria transfer by rain is highly dependent on the regional soil profile and climate conditions.” Via.

anonymous asked:

Hola ur blog is so cool and I think it's really cool you like to help people. I'm a bit confused on what power is in a circuit and it's relationship to current, resistance, and voltage... can you help explain? Tysm!!

The Hydraulic Analogy

There are a couple of times especially in engineering where it is easier to think of DC electric circuits in terms of hydraulic circuits and vice versa. And I think in this case it might help you as well.

Current: The amount of water flowing through a section of a pipe over time

Voltage: The difference in pressure between two points in the water circuit.

Resistance: Narrow constrictions offer high resistance and every pipe like every other wire offers resistance to the flow of water.

Power: It is the rate at which the energy stored in the water is used to drive a mechanical device like a water wheel.

Think of it like this: How fast the wheel is going to spin is dependent on the amount of water hitting it (current) and how much pushing this quantity of water does (voltage). 

(pressure = force applied / area)

Hope this helps and I am glad that you are finding the blog to be useful. Cheers!

* More about the water analogy for electric circuits

** Where does this analogy fail ? (Very important to know)


Fires in large, open spaces like aircraft hangers can be difficult to fight with conventional methods, so many industrial spaces use foam-based fire suppression systems. These animations show such a system being tested at NASA Armstrong Research Center. When jet fuel ignites, foam and water are pumped in from above, quickly generating a spreading foam that floats on the liquid fuel and separates it from the flames. Since the foam-covered liquid fuel cannot evaporate to generate flammable vapors, this puts out the fire. 

The shape of the falling foam is pretty fascinating, too. Notice the increasing waviness along the foam jet as it falls. Like water from your faucet, the foam jet is starting to break up as disturbances in its shape grow larger and larger. For the most part, though, the flow rate is high enough that the jet reaches the floor before it completely breaks up. (Image credit: NASA Armstrong, source)

Around 6 million years ago, the African and Eurasian plates moved together, cutting the Mediterranean Sea off from the Atlantic. Without an influx of water from the Atlantic, evaporation began removing more water from the Mediterranean than rivers could replace. The sea dried out almost completely over the course of a couple thousand years.

About 5.3 million years ago, the Straits of Gibraltar reopened, creating a massive flood into the Mediterranean known as the Zanclean Flood. Water rushed down the straits and into the Mediterranean at speeds as high as 40 m/s (90 mph). At its peak, the Zanclean Flood is estimated to have reached rates 1000 times greater than the volumetric flow rate of the Amazon River. 

A similar breach flood occurred in the Black Sea within the past 10,000 years when the Bosporus became unblocked. That flood likely had a devastating impact on Neolithic societies in the area and may be the inspiration for the floods described in the Epic of Gilgamesh and the Bible. (Image credit: BBC, source)


Valentine’s day Giftbox - The beating heart

Due to the changes in surface tension and the charge concentration on the mercury( the top gif ) and the gallium drop, it contracts and relaxes. This phenomenon is fondly referred to as ‘The beating heart’ by Fluid Dynamicists.

Happy Valentine’s day!

Time is too slow for those who wait, too swift for those who fear, too long for those who grieve, too short for those who rejoice, but for those who love, time is eternity.

- Henry Van Dyke


Engineer school: Done ✔
End of research masted: D-7 ⏳👍

Can’t wait to be done with all of this ! Studying for my oral exam on geophysical fluids dynamics 🌊 and trying to remember all these lessons I had months ago 😮💪

Droplets hitting a liquid surface don’t always coalesce. Above you can see a tiny droplet bounce and skate along the surface of a larger, vibrating drop. The smaller droplet doesn’t coalesce because a tiny layer of air sits between it and the vibrating drop. To actually contact and coalesce, the droplet has to sit still long enough for that air layer to get squeezed out. Instead, the vibration of the larger drop bounces it upwards, refreshing the air layer and scooting the droplet along until it falls off the vibrating drop. (Image credit: C. Kalelkar and S. Phansalkar, source)

Recently, I read a research paper by Professor Manu Prakash from Stanford who has been working on a computer that works on fluid droplets and it is extremely fascinating.

Manipulating Matter

Inspiration: The computers that we have at our home are capable of manipulating Information, but they cannot manipulate Physical matter per se! Ergo, build a device that could process both information and physical matter simultaneously.

The setup is actually relatively simple to understand but the working is a bit tricky. They use a ferrofluid as the droplet and control the way it behaves with a circular magnetic field.

Through the coupling of magnetic and hydrodynamic interaction forces between droplets, AND,OR,XOR,NOT and NAND logic gates, fanouts, full adder, a flip flop and a finite state machine is implemented.

If this is the sort of thing that you are interested in, I strongly recommend you read their paper.

The bigger goal

“We already have digital computers to process information. Our goal is not to compete with electronic computers or to operate word processors on this,”

Prakash said. “Our goal is to build a completely new class of computers that can precisely control and manipulate physical matter. Imagine if when you run a set of computations that not only information is processed but physical matter is algorithmically manipulated as well. We have just made this possible at the mesoscale.”

Have a great day!

- part of ‘Fluid Friday’ series


Fluid Flow Kinetic Art: rheoscopic fluid encased in bubble of plastic shows the intricate motion of turbulence.