Berlin 2005 – scientific programme

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GR: Gravitation und Relativitätstheorie

GR 18: Postersitzung

GR 18.8: Poster

Friday, March 4, 2005, 14:00–19:00, Poster TU BH

Black Hole Excision with Multiple Grid Patches — •Jonathan Thornburg — MPI für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, D-14476 Golm

When using black hole excision to numerically time-evolve a black hole spacetime with no continuous symmetries, most 3+1 finite differencing codes use a Cartesian grid. It’s difficult to do excision on such a grid, because the natural r = constant excision surface must be approximated either by a very different shape such as a contained cube, or by an irregular and non-smooth “LEGO^(TM) sphere” which may introduce numerical instabilities into the evolution.

In this poster I describe an alternate scheme, which uses multiple { r × (angular coordinates) } grid patches, each patch using a different (nonsingular) choice of angular coordinates. This allows excision on a smooth r = constant 2-sphere.

In this poster I discuss some of the key design choices in such a multiple-patch scheme, and present sample results from a prototype implementation for the full nonlinear 3+1 BSSN (Einstein) equations. Finally, I outline current efforts to integrate such a multiple-patch scheme into the Cactus numerical relativity toolkit.