Chapter 4 Vortex detection - Computer Graphics and Visualization

Chapter 6
Applications
This chapter presents four applications, in which actual CFD simulations are analysed
and visualized using the techniques described in the previous chapters. This is done
with two goals in mind. One goal is to illustrate how the techniques can be applied
and how they perform. When several alternative techniques are available for the same
purpose, we will make a comparison. Another goal is to show which insight in the underlying
physical phenomena can be gained by applying the visualization techniques.
The techniques from the previous chapters: particle tracing, vortex detection, and
deformable surfaces may be applied with the following purposes. Particle tracing may
be used to get an overview of the ßow patterns in the ßow Þeld, by releasing particles
in all the nodes of a grid slice. Then, vortex detection techniques may be used to Þnd
vortices in a more directed manner. Finally, deformable surfaces may be applied for
detecting surfaces, in particular separating surfaces.
These techniques are applied to cases resulting from ßow simulations of:
¯ the PaciÞc Ocean
¯ the Bay of Gda«nsk
¯ turbulence in a cylindrical pipe
¯ a Delta-Wing aircraft
The following sections in this chapter describe for each case: the background, the data
set, the applied techniques, the results, and a summary.
6.1 The Pacific Ocean
The Þrst application concerns a numerical simulation of the PaciÞc Ocean [Zhu &
Moorhead, 1995]. The simulation employs the US Navy layered ocean model, a tool
used by the Naval Oceanographic and Atmospheric Research Laboratory to assist in
Æ Æ ocean prediction. Horizontally, the model covers the area from Eto W. Vertically,
the model consists of six layers. The simulation models a period of four years,
1 The Great River approaches from 10,000 mountains // The power of the mountains ßows east with the
River // The Clock Mountain seems like a dragon turning west // Backed by the storm wind, it breaks the
high waves. (Gao Qi)
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