"Slimplectic" Integrators: Variational Integrators for General Nonconservative Systems
Abstract
Symplectic integrators are widely used for long-term integration of conservative astrophysical problems due to their ability to preserve the constants of motion; however, they cannot in general be applied in the presence of nonconservative interactions. In this Letter, we develop the “slimplectic” integrator, a new type of numerical integrator that shares many of the benefits of traditional symplectic integrators yet is applicable to general nonconservative systems. We utilize a fixed-time-step variational integrator formalism applied to the principle of stationary nonconservative action developed in Galley et al. As a result, the generalized momenta and energy (Noether current) evolutions are well-tracked. We discuss several example systems, including damped harmonic oscillators, Poynting-Robertson drag, and gravitational radiation reaction, by utilizing our new publicly available code to demonstrate the slimplectic integrator algorithm. Slimplectic integrators are well-suited for integrations of systems where nonconservative effects play an important role in the long-term dynamical evolution. As such they are particularly appropriate for cosmological or celestial N-body dynamics problems where nonconservative interactions, e.g., gas interactions or dissipative tides, can play an important role.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2015
- DOI:
- 10.1088/2041-8205/809/1/L9
- arXiv:
- arXiv:1506.08443
- Bibcode:
- 2015ApJ...809L...9T
- Keywords:
-
- celestial mechanics;
- methods: numerical;
- planets and satellites: dynamical evolution and stability;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics;
- Mathematics - Numerical Analysis
- E-Print:
- 6 pages, 5 Figures