A lattice Boltzmann method for axisymmetric multiphase flows is presented and validated. The method is capable of accurately modeling flows with variable density. We develop the classic Shan-Chen multiphase model [Phys. Rev. E 47, 1815 (1993)] for axisymmetric flows. The model can be used to efficiently simulate single and multiphase flows. The convergence to the axisymmetric Navier-Stokes equa...

We propose a hybrid lattice-Boltzmann finite-difference method to simulate axisymmetric multiphase flows. The hydrodynamics is simulated by the lattice-Boltzmann equations with the multiple-relaxation-time (MRT) collision model and suitable forcing terms that account for the interfacial tension and axisymmetric effects. The interface dynamics is captured by the finitedifference solution of the ...

As recently found, the distribution of sunspots is non-axisymmetric and spot group formation implies the existence of two persistent active longitudes separated by 180◦. Here we quantitatively study the non-axisymmetry of sunspot occurrence. In a dynamic reference frame inferred from the differential rotation law, the raw sunspot data show a clear clustering around the persistent active longitu...

An exact solution is found describing the collision of a class of axisymmetric pp-waves. They are impulsive in character and their coordinate singularities become point curvature singularities at the boundaries of the interaction region. The solution is conformally flat. Concrete examples are given, involving an ultrarelativistic black hole against a burst of pure radiation or two colliding bea...

Linearly unstable high b tokamak equilibria are shown to be nonlinearly stabilized by an axisymmetric flow containing both toroidal and poloidal components. As fingers of hot plasma produced by pressure driven ballooning instabilities start to convect out towards the bounding wall, an axisymmetric flow is self-consistently generated and opposes the growth of the fingers, maintaining confinement...

We study reaction fronts described by the Kuramoto-Sivashinsky equation subject to a Poiseuille flow. The fronts propagate with or against the flow located inside a two-dimensional slab. Steady front profiles can be flat, axisymmetric, or nonaxisymmetric, depending on the gap between the plates and the average flow speed. We first obtain the steady front solutions, later executing a linear stab...

Azimuthal magnetorotational instability is a mechanism that generates nonaxisymmetric field pattern. Nonlinear simulations in an infinite Taylor-Couette system with current-free external field show, that not only the linearly unstable mode m = 1 appears, but also an inverse cascade transporting energy into the axisymmetric field is possible. By varying the Reynolds number of the flow and the Ha...

In the standard scenario of isolated low-mass star formation, strongly magnetized molecular clouds are envisioned to condense gradually into cores, driven by ambipolar diffusion. Once the cores become magnetically supercritical, they collapse to form stars. Most previous studies based on this scenario are limited to axisymmetric calculations leading to single supercritical core formation. The a...

This paper investigates the characteristics of wall pressure fluctuations in naturally developing boundary layer flows on axisymmetric bodies experimentally. The axisymmetric body has a modified ellipsoidal blunt nose. Flush-mounted microphones are used to measure the wall pressure fluctuations in the boundary layer flow over the body. The measurements are performed in a low noise wind tunnel. ...

The modal low frequency noise generated by a vibrating elastically supported circular plate embedded into a flat infinite baffle has been examined. The main aim of this study is the analysis of the radiation efficiency. Low frequency approximated formulas have been presented. They are valid for all the limiting boundary conditions of the plate with its edge clamped, guided, simply supported or ...