On the relativistic Lattice Boltzmann method for quark-gluon plasma simulations

TL;DR

This paper evaluates the relativistic lattice Boltzmann model for simulating quark-gluon plasma, comparing it with other methods across different regimes, and explores how model assumptions affect accuracy and stability.

Contribution

It provides a comparative analysis of the RLB model against BAMPS and vSHASTA, highlighting its limitations and improvements in ultra-relativistic fluid simulations.

Findings

RLB departs from BAMPS at high speeds and temperatures due to quadratic approximation limitations.

Including quadratic terms in the equilibrium distribution enhances stability.

The RLB model's applicability varies with temperature, velocity, and lattice speed.

Abstract

In this paper, we investigate the recently developed lattice Boltzmann model for relativistic hydrodynamics. To this purpose, we perform simulations of shock waves in quark-gluon plasma in the low and high viscosities regime, using three different computational models, the relativistic lattice Boltzmann (RLB), the Boltzmann Approach Multi-Parton Scattering (BAMPS), and the viscous sharp and smooth transport algorithm (vSHASTA). From the results, we conclude that the RLB model departs from BAMPS in the case of high speeds and high temperature(viscosities), the departure being due to the fact that the RLB is based on a quadratic approximation of the Maxwell-J\"uttner distribution, which is only valid for sufficiently low temperature and velocity. Furthermore, we have investigated the influence of the lattice speed on the results, and shown that inclusion of quadratic terms in the equilibrium distribution improves the stability of the method within its domain of applicability. Finally, we assess the viability of the RLB model in the various parameter regimes relevant to ultra-relativistic fluid dynamics.