An invitation to fluid dynamics from the oceans

The last few weeks, I have been engrossed with the oceans and navigation in their vast expanse. It all started with a couple of movies I watched. The first movie “Kon-Tiki” beautifully portrays the 1947 expedition by Norwegian explorer and ethnographer Thor Heyerdahl across the south pacific, from Peru to polynesia. The remarkable thing was that he achieved this (along with some of his friends) in a balsawood raft! He was trying to establish that Incan people were the first to populate the polynesian islands. This claim is still contested today. Nevertheless, this is an extraordinary feat. They were trying to catch the south equatorial current in their raft. This made me wonder how they were relying on its presence and persistence.

Another movie I watched was “Master and Commander: The Far Side of the World” by Peter Weir. It is about a british captain (played by Russell Crowe) of a small warship trying to maniacally battle a French warship all around South America in in the atlantic and pacific oceans at the turn of the 19th century (fictional story). The thing that most impressed me was that these were both sailing ships. Once again, I started wandering the internet about how the sailors were relying on trade winds to navigate the oceans.

Being a student of fluid mechanics, I started digging deeper and found a treasure trove of books on physical oceanography. The first thing a person must appreciate when trying to study the oceans is the Earth’s rotation. This leads to the Coriolis force as we are observing Earth while moving along with its rotation. The Coriolis force plays a major role in creating the peristent ocean currents and the trade winds. Though I have had an acquaintance with geophysical fluid dynamics, it always takes a spark to make one go mad about a subject. This spark came from Henry Stommel’s great little book “Science of the Seven Seas” (freely available here). The way Stommel has introduced the oceans and its mystery to the reader is wonderful. Any high school student or undergrad picking up this elementary book would really feel what Stommel describes as “the call of the sea”. The fluid mechanics of the ocean and the atmosphere is facinating. While the fluid mechanics as a subject is quite mature with a long illustrated history, the scale of the oceans and the atmosphere leaves our computations and understanding falling short of satisfaction. Of course, this only gives impetus to the thousands of scientists working in this area to search deeper into nature. Henry Stommel was one of the great scientists in this field and his popular introduction definitely leaves a lasting impression about the subject and will inspire many to take up the oceans for their study and lifelong pursuit. I also highly recommend his more technical works (see here).

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