Direct numerical simulation of internal waves with turbulent, sub-surface cores

Internal solitary waves are coherent objects that are ubiquitously observed in the world's coastal oceans. Due to their nearly solitary nature they can transport momentum and energy over long distances (up to thousands of kilometers). Their ability to transport mass efficiently is far less clear. In some instances internal solitary waves exhibit cores that are mostly trapped within the wave, and it is these waves that have the potential to most efficiently transport tracers (e.g. nutrients, pollutants). We report on direct numerical simulations of turbulent, sub-surface cores on the laboratory scale. We use passive tracers to characterize entrainment and transport by these waves. We find that turbulence plays a clear role in the efficiency of entrainment, but also in the efficiency of transport. It does this by modulating episodic shedding from the rear of the core. Time permitting we will discuss extensions of these simulations to wider domains, in order to elucidate the role of transverse instabilities.