Stellar winds emitted by rotating massive stars may show two main components: firstly bipolar lobes with low density and fast wind, produced by the higher T eff and gravity at the poles (" g eff –effect "); secondly, an equatorial disc with a slow dense wind, produced by the stronger opacities at the equator (" κ–effect "). To see the possible role of this anisotropic wind on the shape of LBV n...

Why do galactic bars rotate with high pattern speeds, when dynamical friction should rapidly couple the bar to the massive, slowly rotating dark halo? This longstanding paradox may be resolved by considering the dynamical interactions between the galactic disc and structures in the dark halo. Dynamical friction between small-scale halo structure and the disc spins up and flattens the inner halo...

Abstract Within the framework of Einstein-Maxwell theory geometric properties charged rotating discs dust, using a post-Newtonian expansion up to tenth order, are discussed. Investigating disc’s proper radius and circumference allows us address questions related Ehrenfest paradox. In Newtonian limit there is an agreement with disc from special relativity. The dust also possesses material-like p...

To clarify the behavior of the blade tip vortices of a wind turbine equipped with a brimmed-diffuser shroud, called a “Wind-Lens turbine”, we conducted a three-dimensional numerical simulation using a large eddy simulation (LES). Since this unique wind turbine consists of not only rotating blades but also a diffuser shroud with a broad-ring brim at the exit periphery, the flow field around the ...

Resistance to motion often includes a dry frictional term independent of the speed of an object and a fluid drag term varying linearly with speed in the viscous limit. (At higher speeds, quadratic drag can also occur.) Here, measurements are performed for an aluminium disc mounted on bearings that is given an initial twist and allowed to spin until it comes to a stop. It is found that a sum of ...

Our aim of is to develop a processing method for a rotating disc made of functionally graded materials (FGM), by stacking the slurry, layer by layer in a radial direction. A three-layer functionally graded material of Al/Al2O3 is fabricated with compositions of 10, 20, 30 vol.% Al2O3. The ceramic composition increases from the discs inner (centre) to the outer. The combination of these material...