An experimental and numerical study of impinging, incompressible, axisymmetric, laminar jets is described, where the jet axis of symmetry is aligned normal to the wall. Particle streak velocimetry (PSV) is used to measure axial velocities along the centerline of the flow field. The jet-nozzle pressure drop is measured simultaneously and determines the Bernoulli velocity. The flow field is simul...

Using the two-fluid formalism with the polytropic approximation, we examine the axisymmetric stability criterion for a composite system of gravitationally coupled stellar and gaseous singular isothermal discs (SIDs). Both SIDs are taken to be infinitely thin and are in a self-consistent steady background rotational equilibrium with power-law surface mass densities (∝ r) and flat rotation curves...

one of the most important challenges in the development of urban railways network is the effects of railway vibrations on human and adjacent structures. although various investigations into the sources of railway vibrations have been conducted, very few research works have been reported on the influences of track geometry parameters on the level of vibrations. this is addressed in this research...

This report describes an experimental and numerical study of impinging, incompressible, axisymmetric, laminar jets, where the jet axis of symmetry is aligned normal to the wall. Particle Streak Velocimetry (PSV) is used to measure axial velocities along the centerline of the flow field. The jet-nozzle pressure drop is measured simultaneously and determines the Bernoulli velocity. The flowfield ...

1 Abstract The role of vorticity dynamics in vortex breakdown is examined in a theoretical and computational study. Under the assumptions of steady, incompressible, axisymmetric, invis-cid ow, a theory is developed concerning the interaction of vortex tilting and stretching in the breakdown process. This analytic theory is then connrmed using an unsteady, incompressible, axisymmetric viscous ow...

We investigate the validity of Thorne’s hoop conjecture in non-axisymmetric spacetimes by examining the formation of apparent horizons numerically. If spaces have a discrete symmetry about one axis, we can specify the boundary conditions to determine an apparent horizon even in non-axisymmetric spaces. We implement, for the first time, the “hoop finder” in non-axisymmetric spaces with a discret...

We carry out numerical and mathematical investigations of shear Alfvén waves inside of a spherical shell filled with an incompressible conducting fluid, and bathed in a strong dipolar magnetic field. We focus on axisymmetric toroidal and non-axisymmetric modes, in continuation of a previous work by Rincon & Rieutord (2003, A&A, 398, 663). Analytical expressions are obtained for toroidal eigenmo...

In previous work stable approximately axisymmetric equilibrium configurations for magnetic stars were found by numerical simulation. Here I investigate the conditions under which more complex, non-axisymmetric configurations can form. I present numerical simulations of the formation of stable equilibria from turbulent initial conditions and demonstrate the existence of non-axisymmetric equilibr...

In this article we investigate the LBB condition for axisymmetric flow problems. Specifically, the sufficiency condition for approximating pairs to satisfy the LBB condition established by Stenberg in the Cartesian coordinate setting is presented for the cylindrical coordinate setting. For the cylindrical coordinate setting, the Taylor-Hood (k = 2) and conforming Crouzeix-Raviart elements are s...

Perturbations of the Kerr black hole in the class of axisymmetric artificial black holes. Abstract Artificial black holes (called also acoustic or optical black holes) are the black holes for the linear wave equaion describing the wave propagation in a moving medium. They attracted a considerable interest of physicists who study them to better understand the black holes in general relativity. W...