A comparison of local simulations and reduced models of MRI-induced turbulence

TL;DR

This study compares numerical simulations and a reduced model of MRI-induced turbulence, revealing two stable states influenced by initial conditions, geometry, and thermal properties, with implications for understanding accretion disk dynamics.

Contribution

It demonstrates the validity of a reduced dynamical model in capturing key features of MRI turbulence and explores how geometry and thermal properties affect turbulence states.

Findings

Two quasi-steady states confirmed: quiet and active turbulence.

Geometry influences turbulence behavior, with cubic, bar-shaped, and slab domains showing different dynamics.

Longer cooling times lead to higher turbulence saturation amplitudes.

Abstract

We run mean-field shearing-box numerical simulations with a temperature-dependent resistivity and compare them to a reduced dynamical model. Our simulations reveal the co-existence of two quasi-steady states, a `quiet' state and an `active' turbulent state, confirming the predictions of the reduced model. The initial conditions determine on which state the simulation ultimately settles. The active state is strongly influenced by the geometry of the computational box and the thermal properties of the gas. Cubic domains support permanent channel flows, bar-shaped domains exhibit eruptive behaviour, and horizontal slabs give rise to infrequent channels. Meanwhile, longer cooling time-scales lead to higher saturation amplitudes.