A short introduction to numerical methods used in cosmological N-body simulations

Wojciech Hellwing

We give a short introduction to modern numerical methods commonly used in cosmological N-body simulations. First, we present some simple considerations based on linear perturbation theory which indicate the necessity for N-body simulations. Then, based on a working example of the publicly available GADGET-2 code, we describe particle mesh and Barnes-Hut oct-tree methods used in numerical gravity N-body solvers. We also briefly discuss methods used in an elementary hydrodynamic implementation used for baryonic gas. Next, we give a very basic description of time integration of equations of motion commonly used in N-body codes. Finally we describe the Zeldovitch approximation as an example method for generating initial conditions for computer simulations.

Proceedings of the Polish Astronomical Society, vol. 2, 58-79 (2015)

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