Research

Anyone who swims in the ocean knows how waves can push you around even when they don't break. As the wave crest approaches, you get pulled towards the wave, rise up over the crest, get pushed forwards, and sink back down. It might seem like you're right back where you've started, but if you track the trajectory of an individual fluid particle, it would slowly drift in the direction of wave propagation (see video below). This effect is commonly referred to as the Stokes drift, and it transports more than just water. Anything that floats near the surface, be it plankton or marine litter, is constantly being pushed around by the motion of the waves, potentially travelling very far from their initial location.

In the original 1847 derivation, this drift mostly fell out of the math, and physical explanations for its existence tended to come post factum. In my first paper I answered the following questions:

1. Why, fundamentally, should irrotational surface waves induce a mean motion of water?
2. What sets its magnitude and direction?
3. How is this drift related to other physical quantities such as vorticity and energy density?