Hello all,
here is a new thorn: https://bitbucket.org/mjasiulek/llamawavehyperboloidal
=============================================================================== LlamaWaveHyperboloidal ===============================================================================
This thorn allows to evolve the scalar wave equation in 3D in Kerr spacetimes using Kerr-Schild coordinates which are horizon penetrating. At some transition radius the user can specify where the Kerr-Schild slicing becomes hyperboloidal, thus, 'bends up' to scri (future null infinity). Therefore, no outer (and inner) boundary conditions have to be set, radiation leaves the spacetime 'naturally' through the inner horizon and scri. The waveform at scri is readily computed during the evolution.
It uses Llama's spherical 6-patch coordinates (r,u,v), the method-of-lines with 4th-order Runge-Kutta and 4th-,6th- or 8th-order spatial finite-differencing and matching Kreiss-Oliger dissipation.
In http://arxiv.org/abs/1109.2513 http://arxiv.org/abs/1109.2513 (or http://iopscience.iop.org/0264-9381/29/1/015008/ http://iopscience.iop.org/0264-9381/29/1/015008/) I used this code to study QNMs, late-time tails in Kerr at scri and to test the novel hyperboloidal transformation used to smoothly attach the hyperboloidal slice.
If you find this code useful, please cite the paper Class. Quantum Grav. 29 015008 (2012).
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Enjoy, Michael Jasiulek
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