Oscillations in Katabatic Flows

Imagine a large ice sheet in the north pole. After the sun sets, the ice sheet’s surface is warmer than the atmosphere above, then the surface starts heating the air right on top of it, causing the warmer air to move up while the colder and therefore heavier air away from the surface moves down. Now, imagine the ice sheet has a slope and we’ll see a strong jet of cold air flowing down, causing what is known in Greek as κατάβασις, pronounced as katabatic and meaning descending. The katabatic flow phenomenon is also observed in a wide range of scenarios, and surprisingly air can do a lot of fun things while moving in such a way. In fact, there are oscillations appearing in the motion of the air down the slope that manifest as vorticity rolls in the flow, resembling long snakes moving on top of the surface as seen in the video below. We are trying to provide insight into the amplitude and frequency of such oscillations through Direct Numerical Simulations.

This project was the core of my master’s thesis that was defended on July 2021. [Click here] to see my thesis document!

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