Case Study

Particle Dispersion

Animations below show results plotted for (i) total velocity, (ii) sea-surface height and (iii) the tracks of buoyant particles. The particle-tracking numerical model was based on the hydrodynamics model’s velocity field. This shows the tracks of particles released just outside of the Kingston Harbour and their journey along the shelf. Simulations such as this is used to predict the likely route particles released from a source will take, such as the spread of invasive species introduced through ballast water exchange, or of debris released along the ship’s channel. Particles drift westwards, with the potential to affect Portland Bight and its outer shelf, a designated a protected area.

The result of these numerical experiments showed that currents are primarily wind-driven due to the relatively shallow depth region. Within the Portland Bight area, clockwise and anticlockwise eddies that appeared were directly influenced by wind speed and direction. These features are expected to lengthen the residence time of water-borne contaminants such as invasive species and oil spills.

Horizontal surface velocity vector and total velocity distribution shown in color contours. The unit is m/s.
Particle tracking experiment at sea surface

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