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Non-axisymmetric instabilities in discs with imposed zonal flows
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2016-09-06)
We conduct a linear stability calculation of an ideal Keplerian flow on which a sinusoidal zonal flow is imposed. The analysis uses the shearing sheet model and is carried out both in isothermal and adiabatic conditions, ...
Nonlinear hydrodynamical evolution of eccentric Keplerian discs in two dimensions: validation of secular theory
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2016-03-11)
We perform global two-dimensional hydrodynamical simulations of Keplerian discs with free eccentricity over thousands of orbital periods. Our aim is to determine the validity of secular theory in describing the evolution ...
Zonal flow evolution and overstability in accretion discs
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2017-04-01)
This work presents a linear analytical calculation on the stability and evolution of a compressible, viscous self-gravitating (SG) Keplerian disc with both horizontal thermal diffusion and a constant cooling time-scale ...
MRI turbulence and thermal instability in accretion discs
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2017-06)
A long-standing puzzle in the study of black hole accretion concerns the presence or not of thermal instability. Classical theory predicts that the encircling accretion disc is unstable, as do some self-consistent ...