The article seeks to unify the treatment of conservative force interactions between axi-symmetric bodies and actuators in inviscid flow. Applications include the study of hub interference, diffuser augmented wind turbines and boundary layer ingestion propeller configurations. The conservation equations are integrated over infinitesimal streamtubes to obtain an exact momentum model contemplating...

We consider the classical Cauchy problem for the 3d Navier-Stokes equation with the initial vorticity ω0 concentrated on a circle, or more generally, a linear combination of such data for circles with common axis of symmetry. We show that natural approximations of the problem obtained by smoothing the initial data satisfy good a-priori estimates which enable us to conclude that the original pro...

Aims. Recent observations of XTE J1739-285 suggest that it contains a neutron star rotating at 1122 Hz. Such rotation imposes bounds on the structure of neutron star in XTE J1739-285. These bounds may be used to constrain poorly known equation of state of dense matter at > ∼ 10 15 g cm −3. Methods. One-parameter families of stationary configurations rotating rigidly at 1122 Hz are constructed, ...

To be able to simulate P-wave propagation in a heterogeneous spherical Earth, we solve the acoustic wave equation in spherical coordinates numerically for axi-symmetric media. We employ a high-order nite-diierence scheme which allows us to simulate arbitrary heterogeneous structures with wavelengths as small as 10km. A standard regular gridding in spherical coordinates leads to a continuously d...