Lethe v1.0 official release
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blais...@gmail.com
Oct 15, 2025, 5:07:05 AMOct 15
to deal.II User Group
We are proud to announce the v1.0.2 release of Lethe as well as the publication of its release paper in Computer Physics Communications:
https://doi.org/10.1016/j.cpc.2025.109880
The official release of Lethe is available here:
https://github.com/chaos-polymtl/lethe
When we started Lethe in 2019, it was originally meant to be a high-order finite element solver for single-phase CFD based on deal.II. As time went on, Lethe has continuously grown into a production-ready CFD solver with extensive capability for particle-laden flows (using unresolved or resolved CFD-DEM), granular flows (using DEM) and multiphase flows (using VOF or Phase-Field). Using its matrix-free architecture, Lethe is now faster than it has ever been when it comes to high-order simulation of single-phase turbulent flows (approx. 10-20x faster than before). While we are continuously improving Lethe, we felt it was now a good time to take a step back and reflect on what we had accomplished with this framework since its inception in 2019 and the original release paper of 2020.
Since then, Lethe has been used in over 21 journal publications. It has over 340 stars on Github and we are aware of Lethe users in 6 countries.
The article is open-access and available under a creative common license that allows for commercial usage. Lethe is available under an Apache 2.0 license. We are dedicated to keeping Lethe open-source and well-documented. Lethe now comes packaged with 74 examples and a plethora of unit tests that enables the software to remain robust without hindering innovation and development. To further our commitment to open-source we will shortly also release as open-source the LaTeX source files that generate the article. Essentially, everything we have done is available to everyone for free.
Finally, I would like to thank all of the students, interns and collaborators who have helped us build Lethe over the years. Personally, I would like to thank everyone in the deal.II community without whom I could have never achieved a fraction of what we are doing now. When I first presented Lethe in the deal.II workshop of 2019, it was an intimidating experience to showcase our modest efforts compared to what was already out there, but the warmth I received there really was the thing that encouraged me to go forward and to try and make our own CFD solver from scratch. Thank you all for everything.
https://doi.org/10.1016/j.cpc.2025.109880
The official release of Lethe is available here:
https://github.com/chaos-polymtl/lethe
When we started Lethe in 2019, it was originally meant to be a high-order finite element solver for single-phase CFD based on deal.II. As time went on, Lethe has continuously grown into a production-ready CFD solver with extensive capability for particle-laden flows (using unresolved or resolved CFD-DEM), granular flows (using DEM) and multiphase flows (using VOF or Phase-Field). Using its matrix-free architecture, Lethe is now faster than it has ever been when it comes to high-order simulation of single-phase turbulent flows (approx. 10-20x faster than before). While we are continuously improving Lethe, we felt it was now a good time to take a step back and reflect on what we had accomplished with this framework since its inception in 2019 and the original release paper of 2020.
Since then, Lethe has been used in over 21 journal publications. It has over 340 stars on Github and we are aware of Lethe users in 6 countries.
The article is open-access and available under a creative common license that allows for commercial usage. Lethe is available under an Apache 2.0 license. We are dedicated to keeping Lethe open-source and well-documented. Lethe now comes packaged with 74 examples and a plethora of unit tests that enables the software to remain robust without hindering innovation and development. To further our commitment to open-source we will shortly also release as open-source the LaTeX source files that generate the article. Essentially, everything we have done is available to everyone for free.
Finally, I would like to thank all of the students, interns and collaborators who have helped us build Lethe over the years. Personally, I would like to thank everyone in the deal.II community without whom I could have never achieved a fraction of what we are doing now. When I first presented Lethe in the deal.II workshop of 2019, it was an intimidating experience to showcase our modest efforts compared to what was already out there, but the warmth I received there really was the thing that encouraged me to go forward and to try and make our own CFD solver from scratch. Thank you all for everything.
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