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A discontinuous Galerkin FEM solver for multiphase free surface flows

Project description

Ocellaris is a mass-conserving DG FEM solver for sharp-interface multiphase free-surface flows. Ocellaris can 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. Some examples of what Ocellaris can do, including videos of the results, are shown in the Ocellaris Blog on

Ocellaris is implemented in Python and C++ with FEniCS as the backend for the mesh and finite element assembly. PETSc is used for solving the resulting linear systems.

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

Picture of an Ocellaris clownfish in a triangulated style

Installation and running

Ocellaris requires a full installation of FEniCS with the PETSc linear algebra backend. You can install the dependencies 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 and the possible input parameters 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 is tested with FEniCS Version 2018.1. Earlier versions will NOT work, later version may possibly work.

  • This is an ongoing 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 and Docker Hub container builds. All pull requests and issues should go to the Bitbucket repository. If you want to contribute to Ocellaris, please read the guide to contributing.

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

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