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| Paper: |
Angular Momentum Transport: Local and Global Simulations |
| Volume: |
160, Astrophysical Discs: An EC Summer School |
| Page: |
108 |
| Authors: |
Hawley, John F.; Balbus, Steven A. |
| Abstract: |
The transport of angular momentum is the central issue in accretion disc dynamics. The absence of a theoretical foundation for disc angular momentum transport has led modellers to rely on phenomenological parameterizations such as the Shakura-Sunyaev alpha formalism. Now this is beginning to change; recent analytic studies and three-dimensional simulations have greatly clarified the physics of angular momentum transport mechanisms. Purely hydrodynamic local instabilities and turbulence appear to be ruled out. MHD turbulence, arising from a local MHD instability, has been shown to develop under very general circumstances and to transport angular momentum at dynamically important rates. Progress in understanding the nature of the MHD turbulence continues on two fronts: local simulations with improved physics and large-scale global disc models. |
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