# OpenGeoSys 6.5.5 released!

**URL:** <https://discourse.opengeosys.org/t/opengeosys-6-5-5-released/1629>\
**Category:** Announcements\
**Created:** [May 23, 2025, 5:47pm UTC](https://discourse.opengeosys.org/t/opengeosys-6-5-5-released/1629 "2025-05-23T17:47:34Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![bilke](https://discourse.opengeosys.org/user_avatar/discourse.opengeosys.org/bilke/32/868_2.png) [@bilke](https://discourse.opengeosys.org/u/bilke)\
**Post date:** [May 23, 2025, 5:47pm UTC](https://discourse.opengeosys.org/t/opengeosys-6-5-5-released/1629/1 "2025-05-23T17:47:34Z")

</div>

[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.15496721.svg)](https://doi.org/10.5281/zenodo.15496721)

We are happy to announce the release of **OpenGeoSys 6.5.5**!

## Links

- [Release page on www.opengeosys.org](https://www.opengeosys.org/releases/6.5.5/)
- [GitLab Release](https://gitlab.opengeosys.org/ogs/ogs/-/releases/6.5.5)
- [Zenodo Release](https://zenodo.org/record/15496721)
- [PyPI Release](https://pypi.org/project/ogs/6.5.5/)
- [Conda Release](https://anaconda.org/conda-forge/ogs)

## Highlights

# Process’ changes

## New HMPhaseField process

- [!4809](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/4809) Adds a hydromechanical phase-field process to address typically the hydraulic fracture problem using the phase-field fracture method.

## Deprecated processes removed

- [!5329](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5329) Previously deprecated processes removed: SmallDeformationNonlocal, StokesFlow, TES, ThermoMechanicalPhasefield, and ThermalTwoPhaseFlowPrho.

## Component transport process / reactive transport process with coupling of PHREEQC

- [!5243](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5243) Set the position function in the assembler, so that the retardation factor can be position dependent.

## HeatTransportBHE

- [!5179](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5179) Improve weighting factor calculation used for Algebraic BC in the HEAT\_TRANSPORT\_BHE process.

## Richard’s mechanics process

- [!5255](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5255) Bugfix; compute initial strain from displacement field, do not use strain integration point data.
- [!5316](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5316) Add parallel assembly.

## SmallDeformation

- [!5220](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5220) Add parallel assembly.

## ThermoHydroMechanics

- [!5288](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5288) Add parallel assembly.

# Numerics

- [!5221](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5221) Reuse Jacobian once every n steps to accelerate non-linear solution.
- [!5187](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5187) Multithreading for CG solver can be enabled by setting matrix type (LowerUpper).
- [!5236](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5236) Time dependent deactivation in a domain bounded by a circle or a sphere.
- [!5237](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5237) Analytic block in the numerical Jacobian for CentralDifferences.
- [!5256](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5256) Improvements in ForwardDifferencesJacobian: eliminates one redundant local assembly and leverages the pre-computed analytical Jacobian block.
- [!5318](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5318) Multipliers of IterationBasedTimestepping can be linearly interpolated with `<multiplier_interpolation_type>PiecewiseLinear</multiplier_interpolation_type>`
- [!5262](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5262) Initial implementation of PETSc version of flux corrected transport - **at the moment only for one MPI process**
- [!4926](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/4926) Introduce an iteration number based reduction of Newton-damping.

# Tools

- [!5224](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5224) Remove `tetgen` dependency. We do not bundle `tetgen` anymore. Please install it with your package manager or [Conda](https://github.com/conda-forge/tetgen-feedstock?tab=readme-ov-file#installing-tetgen).
- [!5276](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5276) A tool `mergeMeshToBulkMesh` merges one mesh into a bulk mesh, which can be used in simulations of excavation, backfilling, and successive geo-engineering operations.

# Python & Jupyter

- [!5216](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5216) Conda package includes MFront functionality, see also [Linux mfront by bilke · Pull Request #14 · conda-forge/ogs-feedstock · GitHub](https://github.com/conda-forge/ogs-feedstock/pull/14).
- [!5222](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5222) Bump ogstools (used in benchmarks on the website) to 0.6.0.
- [!5238](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5238) New module ogs.mpl for MPL properties. Basic structure and for now only Constant and Linear properties bound, but more are coming.
- [!5304](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5304) PyVista 0.45, removes vtk-osmesa dependency and `xvfb-run` hacks

# Testing

- [!5204](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5204) Adds a performance test verifying the functionality of !5194 in our CI. This MR can serve as a blueprint for other similar (performance) tests in the future. The MR contains a documentation section in the dev guide, too.

# Logging

- [!5295](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5295) Introduces the command line option (–log-parallel). New default behaviour under MPI: Only rank 0 writes. With option: legacy behaviour.
- [!5295](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5295) Overhaul of log outputs. New log lines, more systematic, less redundancy.
- [!5295](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5295) Signal handling introduced: Terminate and interrupt signals are logged

# Infrastructure

- [!5323](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5323) \[web\] Multi-site search on [opengeosys.org](http://opengeosys.org), Doxygen and ogstools.

# Material Property Library (MPL)

- [!5254](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5254) Add residual saturation in sigmoid function.
- [!5246](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5246) Add possibility to use time and spatial position in Curve, Linear, Exponential and Function property.
- [!5317](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5317) Add the possibility to use curves in Function property.

# Bug fixes

- [!5227](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5227) Avoid dead-lock in MPI when AssemblyException is thrown.
- [!5325](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5325) Fix XDMF/HDF5 output on sub-meshes.

# Documentation

- [!5244](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5244) Add a documentation page, showing how to establish a OGS mesh based on a PETREL structural model.
- [!5275](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5275) Liquid flow documentation.

# Version info

- [!5281](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5281) Compiler updates and c++23 standard:
  - Compiler: gcc-13.3, clang-16.0, `msvc` 17.0 Visual Studio 2022 toolchain 143
  - Libraries: boost-1.84

- [!5314](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5314) Update spdlog to 1.15.3 (updates fmt to 11.2.0)
- [!5329](https://gitlab.opengeosys.org/ogs/ogs/-/merge_requests/5329) Sundials `cvode` solver dependency removed (used only by TES process, which is now deleted)