Aspect ratio dependence in magnetorotational instability shearing box simulations

TL;DR

This study investigates how the size and aspect ratio of the computational domain affect turbulence properties in magnetorotational instability simulations, revealing that larger aspect ratios lead to more consistent and realistic results.

Contribution

It demonstrates that aspect ratio significantly influences turbulence behavior in shearing box simulations, highlighting potential spurious effects in small aspect ratio setups.

Findings

Channel solutions dominate in aspect ratio unity boxes.

Intermittent angular momentum transport diminishes in larger aspect ratio boxes.

Solution characteristics become aspect ratio independent at larger sizes.

Abstract

Aims: We study the changes in the properties of turbulence driven by the magnetorotational instability in a shearing box, as the computational domain size in the radial direction is varied relative to the height Methods: We perform 3D simulations in the shearing box approximation, with a net magnetic flux, and we consider computational domains with different aspect ratios Results: We find that in boxes of aspect ratio unity the transport of angular momentum is strongly intermittent and dominated by channel solutions in agreement with previous work. In contrast, in boxes with larger aspect ratio, the channel solutions and the associated intermittent behavior disappear. Conclusions: There is strong evidence that, as the aspect ratio becomes larger, the characteristics of the solution become aspect ratio independent. We conclude that shearing box calculations with aspect ratio unity or near unity may introduce spurious effects.