Related papers: A Wind Driven Warping Instability in Accretion Dis…
The standard accretion discs are known to be thermally and viscously unstable over a certain range of temperatures. In the inner disc regions there may develop radiation pressure driven instability, which is possibly related to the rapid…
When wind blows over the surface of a viscous liquid, a clear transition from irregular small-amplitude streamwise-oriented wrinkles to well-defined nearly two-dimensional regular waves is observed at a critical wind velocity. We examine…
In this paper, we show that astrophysical accretion disks are dynamically unstable to non-axisymmetric disturbances. This instability is present in any stably stratified anticyclonically sheared flow as soon as the angular velocity…
It is shown that the turbulent flow of acoustic waves propagating outward from the inner edge of the disk causes the accretion of the matter onto the center. The exponential amplification of waves takes place in the resonance region, $…
This paper explores the driving of low-level hydrodynamical activity in protoplanetary-disc dead zones. A small adverse radial entropy gradient, ordinarily stabilised by rotation, excites oscillatory convection (`convective overstability')…
We investigate the stability to nonaxisymmetric perturbations of an accretion disc in which a poloidal magnetic field provides part of the radial support against gravity. Interchange instability due to radial gradients in the magnetic field…
Thermal instability is examined for advection-dominated one-temperature accretion disks. We consider axisymmetric perturbations with short wavelength in the radial direction. The viscosity is assumed to be sufficiently small for the…
Accretion discs around black holes power some of the most luminous objects in the Universe. Discs that are misaligned to the black hole spin can become warped over time by Lense-Thirring precession. Recent work has shown that strongly…
A brief review is given of the Rossby wave instability (RWI) in astrophysical discs. In non-self-gravitating discs, around for example a newly forming stars, the instability can be triggered by an axisymmetric bump at some radius $r_0$ in…
The existence of outflow in accretion flows is confirmed by observations and magnetohydrodynamics (MHD) simulations. In this paper, we study outflows of accretion flows in the presence of resistivity and toroidal magnetic field. The…
By constructing a global model based on 3D local magnetohydrodynamical (MHD) simulations, we show that the disk wind driven by magnetorotational instability (MRI) plays a significant role in the dispersal of the gas component of…
We investigate the generation of intrinsically asymmetric or {\it one-sided} outflows or jets from disk accretion onto rotating stars with complex magnetic fields using axisymmetric (2.5D) magnetohydrodynamic simulations. The intrinsic…
Protostellar discs play an important role in star formation, acting as the primary mass reservoir for accretion onto young stars and regulating the extent to which angular momentum and gas is released back into stellar nurseries through the…
The influence of the bending rigidity of a flexible heaving wing on its propulsive performance in a two-dimensional imposed parallel flow is investigated in the inviscid limit. Potential flow theory is used to describe the flow over the…
(Abridged) We study large-scale winds driven from uniformly bright self-gravitating discs radiating near the Eddington limit. We show that the ratio of the radiation pressure force to the gravitational force increases with height above the…
Considering two-dimensional potential ideal flow with free surface and finite depth, we study the dynamics of small-amplitude and short-wavelength wavetrains propagating on the background of a steepening nonlinear wave. This can be seen as…
We study the stability of poloidal magnetic fields anchored in a thin accretion disc. The two-dimensional hydrodynamics in the disc plane is followed by a grid-based numerical simulation including the vertically integrated magnetic forces.…
We model the formation and evolution of wrinkles in a floating elastic sheet under uniaxial compression. This is a canonical setup in the study of wrinkling, and whilst its static equilibrium configuration is well characterised, its…
We examine the excitation of unstable magnetosonic waves in the radiative envelopes of intermediate- and high-mass stars with a magnetic field of ~kG strength. Wind clumping close to the star and microturbulence can often be accounted for…
Observations of protostellar disks indicate the presence of the magnetic field of thermal (or superthermal) strength. In such a strong magnetic field, many MHD instabilities responsible for turbulent transport of the angular momentum are…