Radial Transport and Meridional Circulation in Accretion Disks

Abstract

Radial transport of particles, elements and fluid driven by internal stresses in three-dimensional (3D) astrophysical accretion disks is an important phenomenon, potentially relevant for the outward dust transport in protoplanetary disks, origin of the refractory particles in comets, isotopic equilibration in the Earth-Moon system, etc. To gain better insight into these processes, we explore the dependence of meridional circulation in 3D disks with shear viscosity on their thermal stratification, and demonstrate strong effect of the latter on the radial flow. Previous locally isothermal studies have normally found a pattern of the radial outflow near the midplane, switching to inflow higher up. Here we show, both analytically and numerically, that a flow, which is inward at all altitudes, is possible in disks with entropy and temperature steeply increasing with height. Such thermodynamic conditions may be typical in the optically thin, viscously heated accretion disks. Disks in which these conditions do not hold should feature radial outflow near the midplane, as long as their internal stress is provided by the shear viscosity. Our results can also be used for designing hydrodynamical disk simulations with a prescribed pattern of the meridional circulation.

11 pages, 5 figures, under review in ApJ, revised version after the referee report

References in corpus (5)

• Equilibration in the Aftermath of the Lunar-Forming Giant Impact
• An Unsplit Godunov Method for Ideal MHD via Constrained Transport in Three Dimensions
• Vertical shear instability in accretion disc models with radiation transport
• Two-Dimensional Transport of Solids in Viscous Protoplanetary Disks
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• Dust Transport in Protoplanetary Disks with Wind-driven Accretion
• Meridional Circulation driven by Planetary Spiral Wakes in Radiative and Magnetized Protoplanetary Discs
• Accretion disc backflow in resistive MHD simulations
• Magnetically threaded accretion disks in resistive magnetohydrodynamic simulations and asymptotic expansion