The following article was written on 1st March 2011 to present OpenCFD’s views on OpenFOAM and open source software. Later in 2011, OpenCFD established the OpenFOAM Foundation and transferred the copyright of the OpenFOAM source code to it, to ensure that OpenFOAM is licensed free and open source only as expressed in this article.
In 2004, OpenFOAM was released as free, open source software, under the GNU general public licence (GPL). It is now one of the most popular software tools for computational fluid dynamics (CFD). OpenCFD, the producer of OpenFOAM, believes in open source software because it gives users the freedom to modify and redistribute the software and a guarantee of continued free use — as long as the terms of the GPL are adhered to. Organisations that appreciate these benefits and share a belief in open source have funded developments that have been released to all. Others “give something back” in other ways, e.g. by testing the code and submitting useful bug reports.
Unfortunately, there may also be organisations and individuals who want to try to exploit OpenFOAM for themselves by including it within non-free and/or closed source software products that do not offer the freedoms described above — even though they have no right to do so. This is a threat to OpenFOAM, not only because it goes against the philosophy of free, open source software, but because it also affects future development of the code. For example, if a new feature is developed for OpenFOAM, but distributed in non-free, closed source software, it is more difficult to get funding to develop that feature for open source release. The feature is then only available to those who can afford it, rather than becoming part of the public commons of free software through the operation of the GPL.
Fortunately, the GPL offers protection against such actions because any modified version of OpenFOAM can only legally be distributed open source under the GPL and software that links intimately enough to OpenFOAM has to be distributed under the GPL as well. In response to the threat posed to OpenFOAM, OpenCFD has begun a campaign to keep OpenFOAM open and free by investigating violations of the GPL and taking action where necessary. This is costly to OpenCFD, both in time and money — resources we would prefer to direct to the development of OpenFOAM — but, given the circumstances, we must act. We will publicise violations of the GPL in respect to OpenFOAM, so that people can make informed decisions about the software they use. We reiterate our commitment to ensure OpenFOAM remains free and open source only and never to be included in any non-free, proprietary software products.