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Lagrangian Transport

Lagrangian transport models are very useful to simulate localized processes with sharp gradients:


submarine outfalls


phytoplankton blooms


sediment erosion due to dredging works


hydrodynamic calibration


oil dispersion


exchanges between diferent areas in a estuary


exchanges between the deep ocean and the continental shelf



Mohidís Lagrangian module uses the concept of tracer. The most important property of a tracer is its position (x,y,z). For a physicist a tracer can be a water mass, for a geologist it can be a sediment particle or a group of sediment particles and for a chemist it can be a molecule or a group of molecules. A biologist can spot phytoplankton cells in a tracer (at the bottom of the food chain) as well as a shark (at the top of the food chain), which means that a model of this kind can simulate a wide spectrum of processes.

The movement of the tracers can be influenced by the velocity field from the hydrodynamic module, by the wind from the surface module, by the spreading velocity from oil dispersion module and by random velocity.

At the present stage the model is able to simulate oil dispersion, water quality evolution and sediment transport. To simulate oil dispersion the lagrangian module interacts with the oil dispersion module, to simulate the water quality evolution the lagrangian module uses the feature of the water quality module. Sediment transport can be associated directly to the tracers using the concept of settling velocity.

Another feature of the lagrangian transport model is the ability to calculate residence times. This can be very useful when studying the exchange of water masses in bays or estuaries.

Figure below represents the information flux between the lagrangian module and other modules of Mohid.


Solar Radiation

Wind Velocity




Volumes / Areas




Mixing Length


Water Quality


Oil Field

Oil Dispersion

Spreading Velocity









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This site was last updated in 05-03-2006

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