Astronomy and Astrophysics – Astronomy
Scientific paper
Jun 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994pasj...46..273n&link_type=abstract
PASJ: Publications of the Astronomical Society of Japan, vol. 46, no. 3, p. 273-283
Astronomy and Astrophysics
Astronomy
5
Accretion Disks, Hydrodynamics, Turbulence, Turbulent Boundary Layer, Mathematical Models, Navier-Stokes Equation, Reynolds Stress
Scientific paper
An attempt to examine how the so-called alpha of the viscosity parameter in accretion disks changes with height is presented. This examination is made by using a one-point closure modeling of turbulence. The model adopted is such a generalized version of the so-called K-epsilon model that it can be applied to compressible turbulence in stratified media. In the K-epsilon, the transport equations of the turbulent kinetic energy (K) and of its dissipation rate epsilon are solved simultaneously. The results show that the alpha-value becomes larger in the region near to the disk surface with low density than in the region near the equator with high density. This is due to the fact that the turbulent diffusion transports the turbulent kinetic energy from the equatorial region (where the energy density of the turbulence is high) toward the surface region (where the energy density of the turbulence is low). By dissipation of this transported energy, the turbulent energy dissipation rate in the surface region is larger than that determined by the balance between local production of turbulent energy and its dissipation.
Kato Shoji
Nakao Yasushi
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