arXiv subjects

Carles Bona

Publications and source records attributed to Carles Bona.

21 records · Page 2Linked to original sources

arXiv1995

New Formalism for Numerical Relativity

We present a new formulation of the Einstein equations that casts them in an explicitly first order, flux-conservative, hyperbolic form. We show that this now can be done for a wide class of time slicing conditions, including maximal slicing, making it potentially very useful for numerical relativity. This development permits the application to the Einstein equations of advanced numerical methods developed to solve the fluid dynamic equations, {\em without} overly restricting the time slicing, for the first time. The full set of characteristic fields and speeds is explicitly given.

gr-qc↗

arXiv1994

Numerical Black Holes: A Moving Grid Approach

Spherically symmetric (1D) black-hole spacetimes are considered as a test for numerical relativity. A finite difference code, based in the hyperbolic structure of Einstein's equations with the harmonic slicing condition is presented. Significant errors in the mass function are shown to arise from the steep gradient zone behind the black hole horizon, which challenge the Computational Fluid Dynamics numerical methods used in the code. The formalism is extended to moving numerical grids, which are adapted to follow horizon motion. The black hole exterior region can then be modeled with higher accuracy.

gr-qc↗

arXiv1994

Invariant Algebraic Slicing of the Spacetime

Using the momentum constraint, the standard evolution system is written in a fully first order form. The class of first order invariant algebraic slicing conditions is considered. The full set of characteristic fields is explicitly given. Characteristic speeds associated to the gauge dependent eigenfields (gauge speeds) are related to light speed.

gr-qc↗