# Angular momentum transport in accretion disks: a hydrodynamical perspective

## TL;DR

This paper reviews recent advances in understanding how purely hydrodynamical processes can contribute to angular momentum transport in accretion disks, a key factor in their evolution and associated astrophysical phenomena.

## Contribution

It synthesizes experimental, theoretical, and numerical findings to evaluate hydrodynamical mechanisms for angular momentum transport in accretion disks, highlighting unresolved questions.

## Key findings

- Hydrodynamical processes may play a significant role in angular momentum transport.
- Recent results from experiments, theory, and simulations support hydrodynamical contributions.
- Many questions about hydrodynamical transport mechanisms remain open.

## Abstract

The radial transport of angular momentum in accretion disk is a fundamental process in the universe. It governs the dynamical evolution of accretion disks and has implications for various issues ranging from the formation of planets to the growth of supermassive black holes. While the importance of magnetic fields for this problem has long been demonstrated, the existence of a source of transport solely hydrodynamical in nature has proven more difficult to establish and to quantify. In recent years, a combination of results coming from experiments, theoretical work and numerical simulations has dramatically improved our understanding of hydrodynamically mediated angular momentum transport in accretion disk. Here, based on these recent developments, we review the hydrodynamical processes that might contribute to transporting angular momentum radially in accretion disks and highlight the many questions that are still to be answered.