Simulating the interaction of internal waves with the bottom boundary layer

Internal waves are a ubiquitous aspect of the coastal ocean, with internal solitary-like waves (or waves that are "close to" having a shape that does not change as the waves propagate) being a particularly energetic example. Such waves propagate over long distances and hence have the potential to impact transport, mixing, and in turn biogeochemistry and biology. In this talk I will concentrate on the manner in which these waves interact with the bottom boundary layer. After reviewing observations and theory, the latter only lightly, for both internal solitary waves and boundary layers I will proceed to discuss how numerical methods for this problem are designed and implemented. The central challenge for the numerical method is the massive disparity in scales associated with the waves (tens to hundreds of meters) and the scales associated with the hydrodynamic instability in the boundary layer (less than a centimetre). I will subsequently present the results of three types of internal wave-boundary layer interactions: 1) Waves over a flat bottom; for which there has been significant development in the literature, 2) Waves over a gently undulating bottom; for which a novel instability can take place, and 3) Shoaling waves. Throughout I will focus on the twin issues of: 1) The manner in which numerical details, which can often be overlooked due to the opaque nature of the vocabulary and notation used to describe them, matter for the interpretation of the numerical model results, and 2) The way in which simulations on the scale of laboratory studies scale up to the field scale.