This short paper describes a numerical model study of an axisymmetric atmospheric circulation (somewhat akin to the Earth’s tropical Hadley circulation) subject to a periodic forcing that cyclically modifies the static stability. The configuration is not particularly realistic as a representation of the true circulation in the Earth’s tropics, but its motivation is justified as an idealized tes...

Axisymmetric pulsations of rotating neutron stars can be excited in several scenarios, such as core-collapse, crust and core-quakes and binary mergers and could become detectable either in gravitational waves or high-energy radiation. Here, we present a comprehensive study of all low-order axisymmetric modes of uniformly and rapidly rotating relativistic stars. Initial stationary configurations...

We develop in this paper a numerical method to simulate three-dimensional incompressible flows based on a decomposition of the flow into an axisymmetric part, in terms of the stream function and the circulation, and a non-axisymmetric part in terms of a potential vector function. The method is specially suited for the study of nonlinear stability of axially symmetric flows because one may follo...

Shapes of vesicles with toroidal topology are studied in the context of curvature models for the membrane. For two simplified curvature models, the spontaneous-curvature (SC) model and the bilayer-couple (BC) model, the structure of energy diagrams, sheets of stationary shapes and phase diagrams are obtained by solving shape equations for axisymmetric shapes. Three different sheets of axisymmet...

We construct a simple symplectic map to study the dynamics of eccentric orbits in non-spherical potentials. The map offers a dramatic improvement in speed over traditional integration methods, while accurately representing the qualitative details of the dynamics. We focus attention on planar, non-axisymmetric power-law potentials, in particular the logarithmic potential. We confirm the presence...

A study of the three-dimensional axisymmetry-breaking instability of an axisymmetric convective #ow associated with crystal growth from bulk of melt is presented. Convection in a vertical cylinder with a parabolic temperature pro"le on the sidewall is considered as a representative model. The main objective is the calculation of critical parameters corresponding to a transition from the steady ...

In this paper an upwind algorithm based on Roe’s scheme is presented for solution of PNS equations. Non iterative-implicit method using finite volume technique is used. The main advantage of this approach, in comparison with similar upwind methods, is reduction of oscillations around sonic line. This advantage causes the present method to be able to analyze supersonic flows with free stream Mac...

The generation of solar non-axisymmetric magnetic fields is studied based on a linear α −Ω dynamo model in a rotating spherical frame. The model consists of a solarlike differential rotation, a magnetic diffusivity varied with depth, and three types of α-effects with different locations, i.e. the tachocline, the whole convective zone and the sub-surface. Some comparisons of the critical α-value...

Elastic spherical shells loaded under uniform pressure are subject to equal and opposite compressive probing forces at their poles to trigger and explore buckling. When the shells support external pressure, buckling is usually axisymmetric; the maximum probing force and the energy barrier the probe must overcome are determined. Applications of the probing forces under two different loading cond...

We examine nonlinear oscillations of slender tori in the vicinity of black holes and compact stars. These tori represent useful probes of the complicated, nonlinear dynamics of real accretion disks and provide at least qualitative understanding of their oscillations. We demonstrate that epicyclic modes of such tori are weakly coupled due to the pressure and gravitational forces. We explore all ...