A Nonhydrostatic Finite-Element Model for Three-Dimensional Stratified Oceanic Flows. Part II: Model Validation

Abstract

A three-dimensional nonhydrostatic ocean model that utilizes finite-element discretizations on structured or unstructured meshes has been formulated. In the current part of this work a first step in the validation of this model is performed. Due to the inherent strengths of the modeling approach in being able to fully simulate three-dimensional flows in arbitrary domains, it has been decided here to focus attention on a single well-studied collection of problems. As such the flow of stratified fluid past an isolated Gaussian seamount is considered. It is shown that at moderate resolutions the model is relatively insensitive to the use of an increasingly fine mesh. In addition, qualitative as well as rough quantitative comparisons are made between results from the current model and previous studies carried out using alternate numerical models. Close agreement is demonstrated, both in the eddy-shedding and flow-trapping structure of the flow, as well as in the generation of internal trapped lee waves. Finally, time-periodic forced flow is examined, where resonantly generated trapped waves on the seamount are shown to be produced. The current model predicts resonant interactions occurring at parameter values consistent with previous numerical as well as linearized analytical studies.