On magnetohydrodynamic turbulence and angular momentum transport in accretion disk boundary layers

Chi Kwan Chan, Martin E. Pessah

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The physical modeling of the accretion disk boundary layer, the region where the disk meets the surface of the accreting star, usually relies on the assumption that angular momentum transport is opposite to the radial angular frequency gradient of the disk. The standard model for turbulent shear viscosity, widely adopted in astrophysics, satisfies this assumption by construction. However, this behavior is not supported by numerical simulations of turbulent magnetohydrodynamic (MHD) accretion disks, which show that angular momentum transport driven by the magnetorotational instability is inefficient in this inner disk region. I will discuss the results of a recent study on the generation of hydromagnetic stresses and energy density in the boundary layer around a weakly magnetized star. Our findings suggest that although magnetic energy density can be significantly amplified in this region, angular momentum transport is rather inefficient. This seems consistent with the results obtained in numerical simulations and suggests that the detailed structure of turbulent MHD boundary layers could differ appreciably from those derived within the standard framework of turbulent shear viscosity.

Original languageEnglish (US)
Title of host publicationSolar and Astrophysical Dynamos and Magnetic Activity
EditorsAlexander G. Kosovichev, Elisabete de Gouveia Dal Pino, Yihua Yan
Number of pages4
StatePublished - Aug 2012
Externally publishedYes

Publication series

NameProceedings of the International Astronomical Union
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221


  • MHD
  • accretion disks
  • turbulence

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science


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