M.Sc. (Applied Mathematics) / Explicit schemes for integrating ODEs and time–dependent partial differential equations (in the method of lines–MoL–approach) are very well–known to be stable as long as the maximum sizes of their timesteps remain below a certain minimum value of the spatial grid spacing. This is the Courant– Friedrich’s–Lewy (CFL) condition. These schemes are the ones traditionally being used for performing simulations in Numerical Relativity (NR). However, due to the above restriction on the timestep, these schemes tend to be so much inadequate for simulating some of the highly probable and astrophysically interesting phenomenae. So, it is of interest this currernt moment to seek or find integrating schemes that may help numerical relativists to somehow circumvent the CFL restriction inherent in the use of explicit schemes. In this quest, a more natural starting point appears to be implicit schemes. These schemes possess a highly desireable stability property – they are unconditionally stable. There also exists a combination of implicit and explicit (IMEX) schemes. Some researchers have already started exploring (since 2009, 2011) these for NR purposes. We report on the implementation of two implicit schemes (implicit Euler, and implicit midpoint rule) for Einstein’s evolution equations. For low computational costs, we concentrated on spherical symmetry. The integration schemes were successfully implemented and showed satisfactory second order convergence patterns on the systems considered. In particular, the Implicit Midpoint Rule proved to be a little superior to the implicit Euler scheme.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:7707 |
| Date | 29 July 2013 |
| Creators | Ndzinisa, Dumsani Raymond |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Johannesburg |
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