Cactus Computational Toolkit

Cactus is an open source problem solving environment designed for scientists and engineers. Its modular structure easily enables parallel computation across different architectures and collaborative code development between different groups. Cactus originated in the academic research community, where it was developed and used over many years by a large international collaboration of physicists and computational scientists. The main development of Cactus has moved to the LSU Capital Center group, while the AEI continues to be involved in developing core infrastructure and thorns, coordinated locally by Thomas Radke.

Web page: http://www.cactuscode.org

Carpet: Fixed mesh refinement

Carpet is a mesh refinement driver for the Cactus framework. Cactus is a framework for solving time-dependent partial differential equations on uniform grids, and Carpet is an extension of Cactus that make mesh refinement possible. The development and integration of Carpet into our physics codes is lead by Erik Schnetter.

Web page: http://www.carpetcode.org

MoL: Method of Lines

The Method of Lines (MoL) is a viewpoint that changes a set of partial differential equations into coupled ordinary differential equations. The MoL code is a simple Cactus thorn that evolves systems written in MoL form. There are three advantages to using MoL. The first is that it is simple to change the numerical method used in a generic way. The second is that it simplifies the coupling between two evolution thorns such as spacetime and matter evolution thorns. The final reason is that code that works with MoL should work with the mesh refinement code Carpet. Development of the MoL thorn has been lead by Ian Hawke.

Whisky

Whisky is a code to evolve the equations of hydrodynamics on curved space. It is being written by and for members of the EU Network on Sources of Gravitational Radiation and is based on the Cactus Computational Toolkit . A version of Whisky should be released into the public domain soon. Whisky has grown from earlier codes such as GR3D and GRAstro_Hydro, but has been rewritten to take advantage of some of the latest research performed here in the EU. The motivation behind Whisky is to compute gravitational radiation waveforms for systems that involve hydrodynamics. Examples would include the merger of a binary system containing a neutron star, which are expected to be reasonably common in the universe and expected to produce substantial amounts of radiation. Other possible sources are given in the projects list. Local development of Whisky is lead by Ian Hawke.

Web page: http://www.whiskycode.org

Kranc: Computer algebra generation of numerical codes

Kranc is a suite of Mathematica packages which comprise a computer algebra toolbox for numerical relativists - Kranc is designed to help wth tasks such as performing 3+1 decompositions, analytical manipulations of tensorial systems of equations such as change of variables, computation of characteristics or linearizations and automatized code generation. The set of tools comprising the Kranc system have been developed at the AEI by Sascha Husa and Christiane Lechner.

Web page: http://numrel.aei.mpg.de/Research/Kranc/