The ‘flip-flop’ phenomenon has now been found to occur on several late-type stars: active longitudes, associated with dark regions of the surface, are seen to jump by 180◦. A simple non-linear non-axisymmetric mean field dynamo model is described, in which for the first time magnetic behaviour is found that is akin to the observed flip-flop.

A new analytic model is presented which accurately estimates the radially averaged axial component of the space&age field of an axisymmetric heavy-ion beam in a cylindrical beam pipe. The model recovers details of the field near the beam ends that are overlooked by simpler models, and the results compare well to exact solutions of Poisson’s equation. Field values are shown for several simple be...

A free surface problem arising in the Czochralski (CZ) crystal growth process is considered. A mathematical model accounting for the interaction of the molten material with applied and induced magnetic fields, temperature-induced convection, rotating boundaries and a free surface is given. The model described avoids some common simplifying assumptions and allows for more general geometries, and...

We present results from axisymmetric, time-dependent magnetohydrodynamic (MHD) simulations of the collapsar model for gamma-ray bursts. Our main conclusion is that, within the collapsar model, MHD effects alone are able to launch, accelerate and sustain a strong polar outflow. We also find that the outflow is Poynting flux-dominated, and note that this provides favorable initial conditions for ...

The structural design and analysis of the BPX Central Solenoid is presented. The largescale structural behavior of the solenoid is simulated with a two-dimensional (2-D) axisymmetric ANSYS' finite element model. The computer model is used to determine the time-dependent stress history in the coils and tie rods, and to perform various structural performance studies. Some of these studies are inc...

Radial electron heat transport in a low collisionality, current-carrying resistive plasma confined in an axisymmetric toroidal magnetic field is hypothesized to be caused by the paleoclassical collisional processes of parallel electron heat conduction and radial magnetic field diffusion. The electron distribution is Maxwellianized and the electron temperature equilibrated over a long length L (...

Baroclinically unstable zones in midlatitudes normally produce medium-scale planetary waves that propagate toward the equator where they generate easterlies while transferring westerly momentum poleward, so that the jet lies in higher latitudes than in the corresponding axisymmetric (eddy-free) state. When the baroclinically unstable zone is moved into low latitudes, however, the equatorward si...

An acoustic prediction capability for supersonic axisymmetric jets was developed on the basis of OVERFLOW Navier-Stokes CFD (Computational Fluid Dynamics) code of NASA Langley Research Center. Reynolds-averaged turbulent stresses in the flow fie ld are modeled with the aid of Spalart-Alimaras one-equation turbulence modeL Appropriate acoustic and outflow boundary conditions were implemented to ...

We determine the equilibrium morphology of a strained solid lm for the case where it wets the substrate (Stranski-Krastanow growth). Using a continuum elasticity model with isotropic surface energy and equal elastic constants in the lm and substrate, we calculate an asymptotic solution for the axisymmetric three-dimensional equilibrium shape of a small island, where the height is much less than...

Several tokamak experiments have reported the existence of plasma equilibria with a zero total toroidal current in their AC operations. By taking a plasma profile model based on linear functions of the poloidal flux function ψ , a variety of equilibrium configurations with a zero total toroidal current have been found. The MHD_N0 stability code [1] is able to compute axisymmetric mode stability...