Related papers: Non-axisymmetric instabilities in discs with impos…
We attempt to address the old problem of plane shear flows: the origin of turbulence and hence transport of angular momentum in accretion flows as well as laboratory flows, such as plane Couette flow. We undertake the problem by introducing…
The short time evolution of three dimensional small perturbations is studied. Exhibiting spectral asymptotic stability, thin discs are nonetheless shown to host intensive hydrodynamical activity in the shape of non modal growth of initial…
We study the stability properties of Rayleigh unstable flows both in the purely hydrodynamic and magnetohydrodynamic (MHD) regimes for two different values of the shear $q=2.1, 4.2$ ($q = - d\ln\Omega / d\ln r$) and compare it with the…
Three-dimensional instability of axisymmetric flow in a rotating disk - cylinder configuration is studied numerically for the case of low cylinders with the height/radius aspect ratio varying between 1 and 0.1. A complete stability diagram…
We perform numerical simulations of the Kelvin-Helmholtz instability in the mid-plane of a protoplanetary disk. A two-dimensional corotating slice in the azimuthal--vertical plane of the disk is considered where we include the Coriolis…
In rotating 3He superfluids the Kelvin-Helmholtz (KH) instability of the AB interface has been found to follow the theoretical model above 0.4 Tc. A deviation from this dependence has been assumed possible at the lowest temperatures. Our…
The assumption of axial symmetry for hypersonic flows over conically shaped geometries is ubiquitous in both experiments and numerical simulations. Yet depending on the free stream conditions, many of these flows are unsteady and their…
Nonhelical turbulence within a linear shear flow has demonstrated efficient amplification of large-scale magnetic fields in numerical simulations, but its precise mechanism remains elusive. The incoherent $\alpha$ mechanism proposes that a…
The dynamics along the particle trajectories for the 3D axisymmetric Euler equations in an infinite cylinder are considered. It is shown that if the inflow-outflow is rapidly increasing in time, the corresponding laminar profile of the…
The Kelvin-Helmholtz instability (KHI) can occur when there is a relative motion between two adjacent fluids. In the case of magnetized plasma, the shear velocity must exceed the local Alfv\'{e}n speed for the instability to develop. The…
Quasi-Keplerian flow, a special regime of Taylor-Couette co-rotating flow, is of great astrophysical interest for studying angular momentum transport in accretion disks. The well-known magnetorotational instability (MRI) successfully…
Hydromagnetic stresses in accretion discs have been the subject of intense theoretical research over the past one and a half decades. Most of the disc simulations have assumed a small initial magnetic field and studied the turbulence that…
The local axisymmetric stability of hydrodynamical and magnetized, nearly-Keplerian gaseous accretion disks around non-rotating black holes is examined in the vicinity of the classical marginally-stable orbit (at radii ~ R_ms). An…
We have previously introduced the parameter `alpha' as an indicator of stability to m=2 nonaxisymmetric modes in rotating, self-gravitating, axisymmetric, gaseous and stellar systems. This parameter can be written as a function of the total…
Observations of galaxies and models of accreting systems point to the occurrence of counter-rotating discs where the inner part of the disc ($r<r_0$) is co-rotating and the outer part is counter-rotating. This work analyzes the linear…
Magnetohydrodynamic kink waves naturally form as a consequence of perturbations to a structured medium, for example transverse oscillations of coronal loops. Linear theory has provided many insights in the evolution of linear oscillations,…
We investigate the dynamics of linear perturbations in Keplerian flow under external stochastic force. To abstract from the details of flow structure and boundary conditions, we consider the problem in the shearing box approximation. An…
We investigate shear driven wave generation at the interface between two immiscible fluids, using an exponential velocity profile with a sharp density interface representing stable stratification. At low Froude and high Bond numbers,…
The Kelvin-Helmholtz instability is well-known in classical hydrodynamics, where it explains the sudden emergence of interfacial surface waves as a function of the velocity of flow parallel to the interface. It can be carried over to the…
Hydrodynamical instabilities are believed to power some of the small scale (0.1-10 pc) turbulence and chemical mixing in the interstellar medium. Identifying such instabilities has always been difficult but recent observations of a wavelike…