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turtleFSI

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What turtleFSI is

turtleFSI is a free, open-source fluid-structure interaction solver written in FEniCS for research groups and individuals. It uses a fully monolithic approach with the classical arbitrary Lagrangian-Eulerian formulation. Users set parameters from the command line and provide problem files defining meshes, markers, boundary conditions, and optional hooks. Mesh movement offers Laplace and biharmonic lifting; biharmonic handling is intended for large deformations but requires more computation and memory. Checkpointing saves states at a chosen frequency and supports restarting from earlier checkpoints. Results can be written as XDMF files for viewing in ParaView. FEniCS high-performance computing features and MPI parallel tasks support parallel runs. Documentation recommends Anaconda or Miniconda on Linux and macOS, with source builds for clusters. Dependencies include FEniCS 2019.1.0, NumPy greater than 1.1X, and Python 3.7 or later. Large 3D cases may encounter MUMPS memory failures.

Who it suits

It suits researchers investigating fluid-structure interaction problems who can work with FEniCS, command-line parameters, and custom problem files. Users needing checkpoints, MPI execution, or ParaView output may benefit from its listed capabilities.

What it does well

Fully monolithic arbitrary Lagrangian-Eulerian solver
Supports Laplace and biharmonic mesh lifting
Checkpointing enables restart from saved states
Runs with MPI parallel tasks
Writes XDMF files for ParaView

What to know first

Large 3D cases may trigger MUMPS memory failures
Biharmonic lifting uses more computation and memory
Requires FEniCS, NumPy, and Python dependencies
Installation is oriented to Linux, macOS, or source builds

Verdict

turtleFSI provides configurable, restartable simulations for research-oriented fluid-structure work. Its dependencies and possible solver memory failures should be considered before larger runs.

Facts from turtleFSI's own pages

Assessment tools: No · turtlefsi2.readthedocs.io, 23 Sept 2026
Checkpointing: Built-in functionality supports saving checkpoints at a chosen frequency and restarting from a previous checkpoint. · turtlefsi2.readthedocs.io, 5 Oct 2026
Command line: Parameters can be controlled from the command line, and a specific problem file can be run with `turtleFSI --problem [path_to_problem]`. · turtlefsi2.readthedocs.io, 12 Oct 2026
Custom problems: Users define problem files with functions for parameters, mesh and boundary markers, boundary conditions, and optional simulation hooks. · turtlefsi2.readthedocs.io, 12 Oct 2026
Dependencies: The documentation lists FEniCS 2019.1.0, NumPy, and Python 3.7 or later as dependencies. · turtlefsi2.readthedocs.io, 12 Oct 2026
Distribution: The development version is available from the project’s GitHub repository and can be installed from source with `python setup.py install`. · turtlefsi2.readthedocs.io, 12 Oct 2026
Features: The solver includes checkpointing and restart support, plus saving files for visualization. · turtlefsi2.readthedocs.io, 12 Oct 2026
Installation: The project recommends Anaconda or Miniconda installation on macOS or Linux and building from source on HPC clusters. · turtlefsi2.readthedocs.io, 12 Oct 2026
Integrations: The documentation describes using ParaView to view simulation output and points users to FEniCS resources for meshing questions. · turtlefsi2.readthedocs.io, 12 Oct 2026
Known issue: The documentation lists an issue page that includes a MUMPS failure error message topic. · turtlefsi2.readthedocs.io, 12 Oct 2026
Known limitation: For large problems, often 3D problems with many degrees of freedom and several tens of processors, the default MUMPS solver may fail, possibly because it lacks memory for the linear system. · turtlefsi2.readthedocs.io, 5 Oct 2026
Lesson library: No · turtlefsi2.readthedocs.io, 23 Sept 2026
License: The repository states that turtleFSI is licensed under GNU GPL version 3 or any later version. · github.com, 12 Oct 2026
Mesh lifting: It provides mesh lifting options including Laplace and biharmonic methods, with biharmonic described as more robust for large deformations but more computationally expensive and memory intensive. · turtlefsi2.readthedocs.io, 5 Oct 2026
Parallel computing: The solver can run with MPI parallel tasks using FEniCS HPC functionality. · turtlefsi2.readthedocs.io, 12 Oct 2026
Purpose: turtleFSI is a monolithic fluid-structure interaction solver written in FEniCS for researchers and others investigating fluid-structure interaction problems. · github.com, 12 Oct 2026
Security: The project pages reviewed do not state security certifications or compliance claims. · github.com, 12 Oct 2026
Simulation controls: Users can set simulation parameters from the command line and supply their own problem file. · turtlefsi2.readthedocs.io, 5 Oct 2026
Solver approach: The project describes turtleFSI as a fully monolithic solver using the classical arbitrary Lagrangian-Eulerian formulation. · joss.theoj.org, 5 Oct 2026
Support: The repository directs users to its GitHub issue tracker to report bugs and other issues. · github.com, 12 Oct 2026
Visualization: Simulation output can include XDMF files for visualization in tools such as ParaView. · turtlefsi2.readthedocs.io, 12 Oct 2026

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