Two-bubble envelope approximation code and results

This deposit contains the code required to carry out the envelope approximation simulations used in the paper with preprint title <em>Vacuum bubble collisions: from microphysics to gravitational waves</em> by Oliver Gould, Satumaaria Sukuvaara, and David Weir. The method and results are based on the following papers: <em>Gravitational Wave Production by Collisions: More Bubbles</em> by Stephan J. Huber and Thomas Konstandin [arXiv:0806.1828]. <em>Gravitational radiation from colliding vacuum bubbles: envelope approximation to many bubble collisions</em> by Arthur Kosowsky and Michael S. Turner [arXiv:astro-ph/9211004]. <em>Gravitational radiation from colliding vacuum bubbles </em>by Arthur Kosowsky, Michael S. Turner and Richard Watkins<em> </em>[Inspire]. In the latter paper the envelope approximation is introduced in Appendix C. There are two files: <strong>dweir-envelope-b2842c4827ad.zip</strong> is a snapshot of the Bitbucket-hosted Git repository for the simulation code, corresponding to the commit tagged <em>v1.1.0</em>. Later versions of the code may exist. The snapshot was generated by the Bitbucket service and does not include the Git metadata. <strong>two-bubbles-envelope-data.tar.gz </strong>is an archive of the simulation results used to generate the envelope approximation results seen in the preprint, as well as numerical tests and some additional numerical explorations. While the results were generated with a slightly earlier version of the code than the tagged release in this deposit, they have been confirmed to be reproducible with the code provided. Both archives contain README.md files with further information.