A discontinuous Galerkin FEM solver for multiphase free surface flows

fem fenics cfd dg navier-stokes multi-phase flow
pip install ocellaris==2019.1.0



Ocellaris is a work in progress to make a mass conserving DG FEM solver for sharp interface multiphase free surface flows. The current goal of the project is to simulate water entry and exit of objects in ocean waves with accurate capturing of the force on the object and the behaviour of the free surface.

Ocellaris is implemented in Python and C++ with FEniCS as the backend for numerics, mesh and finite element calculations.

Ocellaris is named after the Amphiprion Ocellaris clownfish and is written as part of a PhD project at the University of Oslo.

Installation and running

Ocellaris requires a full installation of FEniCS with the PETSc linear algebra backend. You can install the dependecies yourself (you need at least dolfin, h5py, matplotlib and PyYAML), but the easiest way by far is to use a preconfigured Singularity or Docker container. More information on these and installation in general can be found in the user guide.

When Ocellaris is installed you can run the solver with an Ocellaris input file:


Example input files can be found in the demos/ sub-directory of the Ocellaris source code and a description of the Ocellaris input file format is given in the user guide.

First steps

To test the code there are some demo input files in the demos/ directory. Complete input files along with driver scripts are provided for several of the standard benchmark cases like Kovasznay flow and the Taylor-Green vortex in the cases/ directory. More information can be found in the documentation which also contains a description of the input file format.

Please feel free to test Ocellaris, but please keep in mind:

  • Ocellaris is in a state of constant development
  • Ocellaris supports Python 3 only
  • FEniCS DOLFIN with pybind11 Python3 wrappers is required (master version, still unreleased as of November 2017)
  • This is a research project, do not expect results to be correct without proper validation!


The documentation can be found on the Ocellaris web page.


Ocellaris is developed in Python and C++ on Bitbucket by use of the Git version control system. If you are reading this on github, please be aware that you are seeing a mirror that could potentially be months out of date. The github mirror is only updated sporadically—to trigger new Singularity Hub container builds. All pull requests and issues should go to the Bitbucket repository.

Ocellaris is automatically tested on CircleCI and the current CI build status is circleci_status.

Copyright and license

Ocellaris is copyright Tormod Landet, 2015-2017. Ocellaris is licensed under the Apache 2.0 license, a permissive free software license compatible with version 3 of the GNU GPL. See License of Ocellaris for the details.