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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, ...
The stress–pressure relationship in simulations of MRI-induced turbulence
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2016-01-01)
We determine how MRI (magnetorotational instability)-turbulent stresses depend on gas pressure via a suite of unstratified shearing box simulations. Earlier numerical work reported only a very weak dependence at best, ...
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 ...