Self-similar solution of hot accretion flow: the role of kinematic viscosity coefficient

TL;DR

This paper explores how different models of kinematic viscosity influence the structure of hot accretion flows, revealing that a new proposed model results in less efficient wind-driven angular momentum extraction compared to existing prescriptions.

Contribution

Introduces a novel kinematic viscosity model mimicking magnetorotational instability effects and compares its impact on hot accretion flow dynamics with existing models.

Findings

The proposed viscosity model produces less efficient angular momentum extraction via wind.

Self-similar solutions are consistent with hydrodynamical simulation properties.

The model may improve understanding of accretion flow behaviors in numerical simulations.

Abstract

We investigate the dependency of the inflow-wind structure of the hot accretion flow on the kinematic viscosity coefficient. In this regard, we propose a model for the kinematic viscosity coefficient to mimic the behavior of the magnetorotational instability and would be maximal at the rotation axis. Then, we compare our model with two other prescriptions from numerical simulations of the accretion flow. We solve two-dimensional hydrodynamic equations of hot accretion flows in the presence of the thermal conduction. The self-similar approach is also adopted in the radial direction. We calculate the properties of the inflow and the wind such as velocity, density, angular momentum for three models of the kinematic viscosity prescription. On inspection, we find that in the model we suggested wind is less efficient than that in two other models to extract the angular momentum outward where the self-similar solutions are applied. The solutions obtained in this paper might be applicable to the hydrodynamical numerical simulations of the hot accretion flow.