On numerical turbulence generation for test-particle simulations

TL;DR

This paper introduces a modified method for generating artificial magnetic turbulence in test-particle simulations, ensuring isotropy, divergence-free fields, and efficient particle behavior modeling with fewer wave modes.

Contribution

A new turbulence generation method that satisfies key physical properties and reduces computational complexity in test-particle simulations.

Findings

The method fulfills isotropy, equal variance, and divergence-free conditions.

16 wave modes suffice for realistic particle behavior in slab turbulence.

Fewer modes are needed than previously assumed for accurate simulations.

Abstract

A modified method is presented to generate artificial magnetic turbulence that is used for test-particle simulations. Such turbulent fields are obtained from the superposition of a set of wave modes with random polarizations and random directions of propagation. First, it is shown that the new method simultaneously fulfils requirements of isotropy, equal mean amplitude and variance for all field components, and vanishing divergence. Second, the number of wave modes required for a stochastic particle behavior is investigated by using a Lyapunov approach. For the special case of slab turbulence, it is shown that already for 16 wave modes the particle behavior agrees with that shown for considerably larger numbers of wave modes.