# Excitation of turbulence in accretion disks of binary stars by non-linear perturbations

## TL;DR

This paper studies how nonlinear perturbations in accretion disks of binary stars can generate turbulence through shock formation and flow instability, with turbulence characteristics influenced by perturbation parameters.

## Contribution

It investigates the nonlinear evolution of finite-amplitude perturbations and their role in turbulence excitation in accretion disks, highlighting shock formation and flow instability mechanisms.

## Key findings

- Shock waves form at perturbation fronts causing density and velocity discontinuities.
- Turbulence characterized by alpha-parameter up to ~0.1.
- Flow instability leads to disk turbulization influenced by perturbation parameters.

## Abstract

Accretion disks in binary systems can experience hydrodynamic impact at inner as well as outer edges. The first case is typical for protoplanetary disks around young T Tau stars. The second one is typical for circumstellar disks in close binaries. As a result of such an impact, perturbations with different scales and amplitudes are excited in the disk. We investigated the nonlinear evolution of perturbations of a finite, but small amplitude, at the background of sub-Keplerian flow. Nonlinear effects at the front of perturbations lead to the formation of a shock wave, namely the discontinuity of the density and radial velocity. At this, the tangential flow in the neighborhood of the shock becomes equivalent to the flow in in the boundary layer. Instability of the tangential flow further leads to turbulization of the disk. Characteristics of the turbulence depend on perturbation parameters, but alpha-parameter of Shakura-Sunyaev does not exceed ~0.1.