Unravelling cosmic velocity flows: a Helmholtz-Hodge decomposition algorithm for cosmological simulations
Abstract
In the context of intra-cluster medium turbulence, it is essential to be able to split the turbulent velocity field in a compressive and a solenoidal component. We describe and implement a new method for this aim, i.e., performing a Helmholtz-Hodge decomposition, in multi-grid, multi-resolution descriptions, focusing on (but not being restricted to) the outputs of AMR cosmological simulations. The method is based on solving elliptic equations for a scalar and a vector potential, from which the compressive and the solenoidal velocity fields, respectively, are derived through differentiation. These equations are addressed using a combination of Fourier (for the base grid) and iterative (for the refinement grids) methods. We present several idealised tests for our implementation, reporting typical median errors in the order of -, and with 95-percentile errors below a few percents. Additionally, we also apply the code to the outcomes of a cosmological simulation, achieving similar accuracy at all resolutions, even in the case of highly non-linear velocity fields. We finally take a closer look to the decomposition of the velocity field around a massive galaxy cluster.
Keywords
Cite
@article{arxiv.2102.06217,
title = {Unravelling cosmic velocity flows: a Helmholtz-Hodge decomposition algorithm for cosmological simulations},
author = {David Vallés-Pérez and Susana Planelles and Vicent Quilis},
journal= {arXiv preprint arXiv:2102.06217},
year = {2021}
}
Comments
12 pages, 8 figures; accepted for publication in Computer Physics Communications