Flow over topography

Numerical modelling of the world's oceans requires a variety of approaches to study different effects. Of all the effects thought to be important in determining the nature of circulation of the world's oceans, topography is perhaps the least well represented in conventional numerical models. This is largely because conventional numerical techniques make it difficult for the ocean floor to have an entirely general depth profile. Rather, the ocean depth is allowed to take one of a small number of values, with jumps between them. The effect is to replace the smooth gradient of the ocean floor with a staircase.

Idealised topography and domain decomposition

The finite element technique, extensively used in some branches of engineering, but until now relatively unused in ocean modelling, is particularly well suited to the numerical modelling of fluid flow in complex geometries, such as the world's oceans. The elements are designed to conform to the topography, and there is no need to replace smooth gradients with staircases.

In this simulation stratified flow over idealised (Gaussian) topography is studied and the generation of lee waves is shown below.

Density in a vertical plane

Vertical velocity in a vertical plane

Vertical velocity in a horizontal plane