The collapse of a uniformaly rotating, supermassive star (SMS) to a supermassive black hole (SMBH) has been followed recently by means of hydrodynamic simulations in full general relativity. The initial SMS of arbitrary mass M in these simulations rotates uniformly at the mass–shedding limit and is marginally unstable to radial collapse. The final black hole mass and spin have been determined t...

Direct numerical simulations are used to investigate the Open Von Kármán Swirling Flow, a new type of unsteady three-dimensional flow that is formed between two counter-rotating coaxial disks with an axial extraction enclosed by a cylinder chamber. Solution verification shows that monotonic convergence is achieved on three systematically refined grids for average pressure at the disk periphery ...

Screw instability of the magnetic field connecting a rotating black hole (BH) with its surrounding disk is discussed based on the model of the coexistence of the Blandford-Znajek (BZ) process and the magnetic coupling (MC) process (CEBZMC). A criterion for the screw instability with the state of CEBZMC is derived based on the calculations of the poloidal and toroidal components of the magnetic ...

In paper I, we showed that time-dependent general relativistic magnetohydrodynamic (GRMHD) numerical models of accretion disks, although being highly turbulent, have surprisingly simple electromagnetic properties. In particular, the toroidal current density in the disk takes the form dIφ/dr ∝ r . Guided by this simplicity, we use a time-dependent general relativistic force-free electrodynamics ...

If a Kerr black hole is connected to a disk rotating around it by a magnetic field, the rotational energy of the Kerr black hole provides an energy source for the radiation of the disk in addition to disk accretion. The black hole exerts a torque on the disk, which transfers energy and angular momentum between the black hole and the disk. If the black hole rotates faster than the disk, energy a...

Existing experimental and theoretical studies are discussed which lead to the clear hypothesis of a hitherto unidentified convective instability mode that dominates within the boundary-layer flow over slender rotating cones. The mode manifests as Görtlertype counter-rotating spiral vortices, indicative of a centrifugal mechanism. Although a formulation consistent with the classic rotating-disk ...

A correlation of the logarithmic values of the in vitro dissolution rate, G, and the apparent solubility, S, was evaluated in phosphate and ammonium acetate buffer at an initial pH of 7. The dissolution rates were determined with a newly designed and build miniaturized rotating disk equipment, as well as with a traditional rotating disk apparatus. The two apparatuses gave the same correlation p...

A second error appears in the Comment: only one moving object (one rotating disk) had been considered according to Fig. (2). However, two moving objects (two disks rotating in opposite directions v and –v), had been used in [2], and special relativity predicts Doppler shifts between all moving objects. Hence, a shift is expected to occur for a signal emitted from a moving object (rotating disk ...

We present a solution to the time discontinuity paradox in rotating reference frames by postulating that time is periodic. A kinematic restriction is enforced that requires the discontinuity to be an integral number of the periodicity of time. Quantized radii emerge for which the associated tangential velocities are less than the speed of light. Using the de Broglie relationship, we show that q...

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