Gallery: Multipatch wave equation

The Llama code is a 3-dimensional multiblock infrastructure for Cactus based on Carpet. It provides different patch systems that cover the simulation domain by a set of overlapping patches. Each of these patches has local cooordinates with a well-defined relation to global Cartesian coordinates. Information between the different patches is communicated via interpolation in the overlap zones.

Here we show an example evolution of a wave equation on a Kerr background using the "Thornburg2004nc" patch-system, consisting of 90 degree by 90 degree wedges centred on each of the +x, -x, +y, -y, +z, -z coordinate axes. This provides a complete covering of a region between rmin and rmax with smooth inner and outer boundaries. The initial data is an l=2, m=2 spherical harmonic in the angular directions, and a Gaussian in the radial direction. An alternative patch system, "Thornburg2004", adds a cubical patch enclosing r < rmin in which standard Carpet box-in-box mesh refinement can be employed. This is used in the GW150914 gravitational wave gallery example.

We ask that if you make use of the Llama code, then please cite Llama, the Einstein Toolkit, the Carpet mesh-refinement driver and Cactus.

Simulation details

Computational details

Parameter FileKerr-Schild_Multipole.par
Submission commandsimfactory/bin/sim create-submit Kerr-Schild_Multipole --parfile arrangements/Llama/LlamaWaveToy/par/Kerr-Schild_Multipole.par
Total memory800 MB
Run timeAbout 10 minutes on 2​ laptop cores
Results (226MB)Kerr-Schild_Multipole-20201108.tar.gz

This example was last tested on 08-November-2020.


BH horizons

Projection into the xy plane of an l=2, m=2 multipole evolved with the wave equation on a spherical grid made of 6 coordinate patches. Image created using the VisIt file Kerr-Schild_Multipole.session