Oscillatory jets and instabilities in a rotating cylinder

Oscillatory jets and instabilities in a rotating cylinder

Pressure- and magnetic shear-driven instabilities in rotating MHD jets

We derive new stability criteria for purely MHD instabilities in rotating jets, in the framework of the ballooning ordering expansion. Quite unexpectedly, they involve a term which is linear in the magnetic shear. This implies that cylindrical configurations can be destabilized by a negative magnetic shear as well as by a favorable equilibrium pressure gradient, in distinction with the predicti...

Kink instabilities in jets from rotating magnetic fields

We have performed 2.5D and 3D simulations of conical jets driven by the rotation of an ordered, large-scale magnetic field in a stratified atmosphere. The simulations cover about three orders of magnitude in distance to capture the centrifugal acceleration as well as the evolution past the Alfvén surface. We find that the jets develop kink instabilities, the characteristics of which depend on t...

Experimental and numerical results on three-dimensional instabilities in a rotating disk–tall cylinder flow

The three-dimensional axisymmetry-breaking instability of axisymmetric flow between a rotating lid and a stationary cylinder is analyzed both numerically and experimentally for the case of tall cylinders with the height/radius aspect ratio between 3.3 and 5.5. A complete stability diagram for the primary three-dimensional instability is obtained experimentally and computed numerically. The inst...

Sidewall boundary layer instabilities in a rapidly rotating cylinder driven by a differentially corotating lid

The flow in an enclosed completely filled rapidly rotating cylinder that is driven by the differential corotation of the top lid is studied numerically. Although the flow is in a very simple geometry, the fast background rotation and large differential rotation of the lid lead to very thin boundary layers with a variety of instability modes with very fine spatial scales as well as inertial wave...