# Gmsh

# A three-dimensional finite element mesh generator with built-in pre- and post-processing facilities

#### Christophe Geuzaine and Jean-François Remacle

Gmsh is an open source 3D finite element mesh generator with a built-in CAD engine and post-processor. Its design goal is to provide a fast, light and user-friendly meshing tool with parametric input and advanced visualization capabilities. Gmsh is built around four modules: geometry, mesh, solver and post-processing. The specification of any input to these modules is done either interactively using the graphical user interface, in ASCII text files using Gmsh's own scripting language (`.geo` files), or using the C++, C, Python or Julia Application Programming Interface (API).

See this general presentation for a high-level overview of Gmsh and recent developments, the screencasts for a quick tour of Gmsh's graphical user interface, and the reference manual for a more thorough overview of Gmsh's capabilities, some frequently asked questions and the documentation of the C++, C, Python and Julia API.

The source code repository contains many examples written using both the built-in script language (see e.g. the tutorials and demos) and the API.

## Download

Gmsh is distributed under the terms of the GNU General Public License (GPL):

- Current stable release (version 4.5.3, 22 February 2020):
  - Download Gmsh for Windows 64-bit, Windows 32-bit, Linux 64-bit, Linux 32-bit or MacOS
  - Download the source code
  - Download the Software Development Kit (SDK) for Windows 64-bit, Windows 32-bit, Linux 64-bit, Linux 32-bit or MacOS

  Make sure to read the tutorials before sending questions or bug reports. See the C++, C, Python and Julia examples on how to use the Gmsh API to develop your own applications using the SDK.

- Development version:
  - Download the latest automatic Gmsh snapshot for Windows 64-bit, Windows 32-bit, Linux 64-bit, Linux 32-bit or MacOS
  - Download the latest automatic source code snapshot
  - Download the latest automatic SDK snapshot for Windows 64-bit, Windows 32-bit, Linux 64-bit, Linux 32-bit or MacOS
  - Access the Git repository: '`git clone https://gitlab.onelab.info/gmsh/gmsh.git`'

- All versions: binaries and sources

If you use Gmsh please cite the following reference in your work (books, articles, reports, etc.): C. Geuzaine and J.-F. Remacle. Gmsh: a three-dimensional finite element mesh generator with built-in pre- and post-processing facilities. International Journal for Numerical Methods in Engineering 79(11), pp. 1309-1331, 2009. You can also cite additional references for specific features and algorithms.

To help fund Gmsh development, you can make a donation.

## Documentation

- General presentation with high-level overview of Gmsh and recent developments
- Gmsh reference manual (stable release) (also available in PDF and in plain text)
- Gmsh reference manual (development version) (also available in PDF and in plain text)
- Screencasts showing how to use the graphical user interface
- Gitlab development site with a wiki, time line of changes and the bug tracking database
- Changelog
- Mailing lists:
  - gmsh (archived here) is the public mailing list for Gmsh discussions
  - gmsh-announce (archived here) is a moderated ("read-only") list for announcements about new releases and other Gmsh news

Please report all issues on `https://gitlab.onelab.info/gmsh/gmsh/issues`.

## Licensing

Gmsh is copyright (C) 1997-2020 by C. Geuzaine and J.-F. Remacle (see the CREDITS file for more information) and is distributed under the terms of the GNU General Public License (GPL) (version 2 or later, with an exception to allow for easier linking with external libraries).

In short, this means that everyone is free to use Gmsh and to redistribute it on a free basis. Gmsh is not in the public domain; it is copyrighted and there are restrictions on its distribution (see the license and the related frequently asked questions). For example, you cannot integrate this version of Gmsh (in full or in parts) in any closed-source software you plan to distribute (commercially or not). If you want to integrate parts of Gmsh into a closed-source software, or want to sell a modified closed-source version of Gmsh, you will need to obtain a different license. Please contact us directly for more information.

## Screenshots

These are two screenshots of the Gmsh user interface, with either the light or dark user interface theme. See the ONELAB web site for more.

## Links

- Gmsh uses OpenCascade for constructive geometry features, and interfaces the optional external mesh and mesh adaptation librairies Netgen and Mmg3d.
- Gmsh's cross-platform graphical user interface is based on FLTK and OpenGL.
- Gmsh's high quality vector PostScript, PDF and SVG output is produced by GL2PS.
- Gmsh implements a ONELAB server to drive external solvers such as the open source finite element solver GetDP. Gmsh and GetDP are bundled in the ONELAB app for iPhone, iPad and Android devices.

## References

Gmsh

- C. Geuzaine and J.-F. Remacle. Gmsh: a three-dimensional finite element mesh generator with built-in pre- and post-processing facilities. International Journal for Numerical Methods in Engineering 79(11), pp. 1309-1331, 2009.

Cross-patch and STL meshing (Compounds)

- J.-F. Remacle, C. Geuzaine, G. Compère and E. Marchandise. High-quality surface remeshing using harmonic maps. International Journal for Numerical Methods in Engineering 83(4), pp. 403-425, 2010.
- E. Marchandise, C. Carton de Wiart, W. G. Vos, C. Geuzaine and J.-F. Remacle. High quality surface remeshing using harmonic maps. Part II: surfaces with high genus and of large aspect ratio. International Journal for Numerical Methods in Engineering 86(11), pp. 1303-1321, 2011.
- E. Marchandise, J.-F. Remacle and C. Geuzaine. Optimal parametrizations for surface remeshing. Engineering with Computers, December 2012, pp. 1-20.

Quad meshing

- J.-F. Remacle, J. Lambrechts, B. Seny, E. Marchandise, A. Johnen and C. Geuzaine. Blossom-Quad: a non-uniform quadrilateral mesh generator using a minimum cost perfect matching algorithm. International Journal for Numerical Methods in Engineering 89, pp. 1102-1119, 2012.
- J.-F. Remacle, F. Henrotte, T. Carrier-Baudouin, E. Béchet, E. Marchandise, C. Geuzaine and T. Mouton. A frontal Delaunay quad mesh generator using the L∞ norm. International Journal for Numerical Methods in Engineering, 94(5), pp. 494-512, 2013.

High-order meshing

- A. Johnen, J.-F. Remacle and C. Geuzaine. Geometric validity of curvilinear finite elements. Journal of Computational Physics 233, pp. 359-372, 2013.
- A. Johnen, J.-F. Remacle and C. Geuzaine. Geometric validity of high-Order triangular finite elements. Engineering with Computers 30 (3), pp. 375-382, 2014.
- T. Toulorge, C. Geuzaine, J.-F. Remacle, J. Lambrechts. Robust untangling of curvilinear meshes. Journal of Computational Physics 254, pp. 8-26, 2013.

High-order visualization

- J.-F. Remacle, N. Chevaugeon, E. Marchandise and C. Geuzaine. Efficient visualization of high-order finite elements. International Journal for Numerical Methods in Engineering 69(4), pp. 750-771, 2007.

Homology solver

- M. Pellikka, S. Suuriniemi, L. Kettunen and C. Geuzaine. Homology and cohomology computation in finite element modeling. SIAM Journal on Scientific Computing 35(5), pp. 1195-1214, 2013.