open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello everyone!

I am modelling a part of the Paraná River in Argentina, where i want to know what happen if i put five sources near a fluvial port ( i am studying the influence of remove part of the sediment there). I am using telemac 3d with Sedi3d, and with the small particles i dont have a problem, but when i increase the size of the particles the concentration and the deposition increase excessively.

At first i used 0.063 mm of diameter with a concentration per source 36 kg/m3 and 1 m3/s is the flow of the source. The result was a maximum concentration in the river of 0.4 kg / m3 and a bed evolution of a millimeter.

When i change to 0.3 mm with a concentration per source 6 kg/m3 and 1 m3/s. the maximum concentration was 1 kg/m3 and the bed evolution increase to 12 meters.

Obviously i change the settling velocity and this kinds of parameters but i think that the quantity of sediment is diferent and i dont know why.

Hello,
If I understand well your question, probably your model behavior and observed result has a physical sense. In fact, the non-linearity associated to the sediment size (weight) and its relationship with the settling velocity computation makes that, under particular flow conditions (forcing), your model delivers this kind of "non-physical" result.
A quick computation of the Bagnold number (ratio between the settling and friction velocities) can show the main tendency of your model, that is if the sediments will be prone to be transported in suspension or next to the bottom.
I hope it helps,
Best wishes,
Pablo