Delft3D FM

Delft3D Flexible Mesh is Deltares' flagship modelling suite for rivers, estuaries, lakes and coastal seas: 1D/2D/3D hydrodynamics on unstructured meshes, with tightly coupled modules for waves, sediment transport and morphology, and water quality (DELWAQ). It is the reference tool where rivers meet salt water — estuarine salinity, sediment budgets, delta morphodynamics.

The computational engines are open source, and a large international user community exists; in practice serious use often pairs the free engines with Deltares' service packages and GUIs. For estuarine and coastal-river problems it has few equals at any price.