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SELFE modelling system

SELFE (Semi-implicit Eulerian-Lagrangian Finite Element) is an open-source community-supported modelling system, based on unstructured grids, designed for the effective simulation of 3D baroclinic circulation across river-to-ocean scales. It uses a semi-implicit finite-element Eulerian-Lagrangian algorithm to solve the Navier-Stokes equations (in either hydrostatic and non-hydrostatic form), written to realistically address a wide range of physical processes and of atmospheric, ocean and river forcings. The numerical algorithm is high-order, and stable and computationally efficient (but slightly more expensive than ELCIRC). Although not guarenteed in the numerical scheme, the volume conservation is good. It also naturally incorporates wetting and drying of tidal flats. While originally developed to meet specific modeling challenges for the Columbia River, SELFE has been extensively tested against standard ocean/coastal benchmarks and applied to a number of bays/estuaries around the world, in the context of general circulation, tsunami and storm surge inundation, water quality, oil spill, sediment transport, coastal ecology, and wave-current interaction.

The source code and other information can be downloaded from SELFE web site: [1]. The plot below shows a snapshot of various modules inside SELFE (v3.2), which is not released yet but can be requested (see Beta version testing).

SELFE modeling system

Major Characteristics of SELFE

Unstructured triangular grids + implicit time stepping + Eulerian-Lagrangian Method = flexibility, accuracy, & robustness & efficiency (F.A.R.E.)
  • Finite element/volume formulation
  • Hydrostatic & non-hydrostatic options
  • Unstructured grid in the horizontal dimension
  • Hybrid SZ coordinates in the vertical dimension (with Z layers being optional)
  • Semi-implicit time stepping (no mode splitting): no CFL stability constraints -> numerical efficiency
  • Robust matrix solver;
  • Higher-order Eulerian-Lagrangian treatment of advection
  • Natural treatment of wetting and drying suitable for inundation studies
  • Three transport algorithms: Eulerian-Lagrangian, upwind, or TVD
  • Volume conservation good
  • Mass conservative transport

Modeling system & application areas

  • 3D baroclinic cross-scale river-estuary-plume-shelf circulations
  • Tsunami hazards
  • Storm surge
  • Sediment transport
  • Ecology & water quality
  • Oil spill
  • Short wave-current interaction