Simulating gravitational motion, gas dynamics, and structure in the cosmos

TL;DR

This paper introduces ChaNGa, a sophisticated simulation code for modeling gravitational and gas dynamics in cosmology, explaining its algorithms and computer science foundations for understanding galactic evolution.

Contribution

It provides an accessible overview of ChaNGa's algorithms and data structures, aiding learning and application in cosmological simulations.

Findings

ChaNGa effectively models galactic structures.

The code incorporates leapfrog integration and smoothed particle hydrodynamics.

Problems facilitate understanding of cosmological concepts.

Abstract

We provide introductory explanations and illustrations of the $N$-body hydrodynamics code Charm N-body GrAvity solver (ChaNGa). ChaNGa simulates the gravitational motion and gas dynamics of matter in space, with the goal of modeling galactic and/or cosmological structure and evolution. We discuss the algorithm for leapfrog integration and smoothed particle hydrodynamics and computer science concepts used by the program, including the binary data structure for the particle positions. Our presentation borrows from the doctoral dissertation of J.\ G.\ Stadel. Problems are provided in order to use ChaNGa to learn or solidify some cosmological concepts.