Aspects of the spectral-element-based simulation of a model internal swash zone

We examine the design and implementation of a numerically simulated internal swash zone (ISZ) in a two-layer continuous stratification, in two-dimensions. An ISZ operates over slower timescales and is forced by longer internal wavelengths as compared to its surface counterpart (Emery and Gunnerson 1973). Moreover, such waves drives mixing of near-boundary fluid and energizes the bottom boundary layer.

The setup and computational investigations are motivated by an on-going field project which focuses on the internal swash zone in energized by the internal seiche in seasonally stratified Cayuga lake in NY state (Schweitzer 2015). The lake internal swash zones are an efficient proxy for equivalent physical processes driven by the lower-mode internal tide on the oceanic continental slope.

We will first present an overview of deep-water and on-slope boundary condition design, implementation and validation. We will then present the study of the interaction of the incident created wave with the sloping boundary for different values of wavelengths, Froude numbers and slope values. We will also discuss the implications of our findings for future three-dimensional simulations of internal-wave-induced transition and turbulence on the deformed sloping boundary.