Fluids: Volcanoes, Infection Control and Instabilities Fluid Mechanics is a subject that deals with the study of many astounding phenomena in fluids (gases or liquids), and it has applications in a vast number of fields such as Environment, Climate, Geology, Engineering, and Biological Fluids, its versatility is surprising.
The apparently unrelated studies of volcanoes and infection control can be studied using the same plume theory of fluid mechanics, and in recent years, researchers have used the study of plumes (a plume is one fluid going into another fluid because of the density difference between them) to understand the behavior of volcanoes.
They have run experiments using a salt water plume going down into fresh water (since salt water is more dense than fresh water) and into water which has been stratified (i.e., it has been set up such that it has an increasing or decreasing density with height) so as to resemble the atmosphere. These experiments have given them deep insights into conditions at the source of the volcano – which cannot be found using direct measurement. Researchers in the area of Environmental Fluid Dynamics are now using laboratory experiments to understand how to prevent air-borne infection spread in hospitals. It is estimated that about 2 million people in the United States are affected each year by air-borne infections – and this number is expected to be worse in countries with a lack of good health care facilities. Therefore, the study of the prevention of air-borne infection by understanding how the pathogens propagate in air, using fundamental Fluid Mechanics, is an important ongoing research problem. Fluid Mechanics also helps researchers study the climate by observations of winds, among other things, and using theoretical models derived using mathematical equations. Scientists also use Fluid Mechanics to study the mechanics of blood circulation and flows in blood vessels. Thus, the study of Fluid Mechanics enables one to engage themselves in a vast number of fields, each of which has a direct application to real-world situations. Another rather seemingly fundamental problem encountered in Fluid Mechanics is the Rayleigh-Taylor instability. The atmospheric pressure (i.e., the pressure exerted by air on anything surrounding it), as we know, is approximately about 105 Pascal (1 Pa = 1 N/m2). This pressure is also equivalent to the pressure exerted by a column of water that is about 10 meters in length. Now, one might ask: what does this mean physically? Well, it means that if you had a very long glass filled with water that is about 10 meters in length, and you suspended it upside down, the water would not fall out of the glass since the pressure in the atmosphere is sufficient to keep it in. However, as we notice in our everyday life, the atmospheric pressure can’t keep the water in even a very short glass – say one that is about 10 centimeters in length. The moment we reverse the glass, the water falls straight out and onto the floor. This, and many other such phenomena, can be explained by what is known as the Rayleigh-Taylor instability, which is one of the many astonishing instabilities encountered in fluid mechanics.