相关论文: The best whistler: a cavitating tip vortex

We develop a search method for gravitational ringing of black holes. The gravitational ringing is due to complex frequency modes called the quasi-normal modes that are excited when a black hole geometry is perturbed. The detection of it…

The discrete kinetic model is used to study the propagation of sound waves in system of hard-disk-like rotating stars (or vortex gases). The anomalous (negative) attenuation or amplification which is possibly due to the binary collision of…

A new method of detection and measurement of quantum vorticity by scattering second sound off quantized vortices in superfluid Helium is suggested. Theoretical calculations of the relative amplitude of the scattered second sound waves from…

Blade-tip vortices can lead to wakes, cavitation and noise, and their control remains a significant challenge for tidal and wind turbines. In the present work, we propose and investigate controlling tip vortices through local permeability.…

Nucleation of vortices in a superconductor below the first critical field can be assisted by transverse sound in the GHz frequency range. Vortices will enter and exist the superconductor at the frequency of the sound. We compute the…

The source of the hummingbirds distinctive hum is not well understood, but there are clues to its origin in the acoustic nearfield and farfield. To unravel this mystery, we recorded the acoustic nearfield generated by six freely hovering…

An increasing number of blazars have been reported to show jet wobbling (i.e., non-regular rotations of the structural position angle of their innermost jets in the plane of the sky with amplitudes between 20 deg. and 50 deg., and time…

Rotational superradiance was predicted theoretically decades ago, and is chiefly responsible for a number of important effects and phenomenology in black-hole physics. However, rotational superradiance has never been observed…

Since Marco Polo (1) it has been known that some sand dunes have the peculiar ability of emitting a loud sound with a well defined frequency, sometimes for several minutes. The origin of this sustained sound has remained mysterious, partly…

Sound generation and -interaction is highly complex, nonlinear and self-organized. Already 150 years ago Lord Rayleigh raised the following problem: Two nearby organ pipes of different fundamental frequencies sound together almost inaudibly…

Vorticity in two-dimensional superfluids is subject to intense research efforts due to its role in quantum turbulence, dissipation and the BKT phase transition. Interaction of sound and vortices is of broad importance in Bose-Einstein…

There are numerous devices currently known with the purpose of reducing the irregularity of the flow upstream of the propeller and to decrease by that means the propeller-induced vibration and noise. Many of these devices are wing-shaped…

We investigate wave-vortex interaction emerging from an expanding compact vortex cluster in a two-dimensional Bose-Einstein condensate. We adapt techniques developed for compact gravitational objects to derive the characteristic modes of…

We use an optical centrifuge to deposit a controllable amount of rotational energy into dense molecular ensembles. Subsequent rotation-translation energy transfer, mediated by thermal collisions, results in the localized heating of the gas…

Humpback whales can generate intricate bubbly regions, called bubble nets, via their blowholes. They appear to exploit these bubble nets for feeding via loud vocalizations. A fully-coupled phase-averaging approach is used to model the flow,…

We treat string propagation and interaction in the presence of a background Neveu-Schwarz three-form field strength, suitable for describing vortex rings in a superfluid or low-viscosity normal fluid. A circular vortex ring exhibits…

This study introduces a vortex gust generation method for isolated vortices impacting a downstream airfoil that is applicable to both numerical simulations and experiments. The vortex gust is generated by a symmetric airfoil undergoing a…

Employing Unruh's analogy to gravity, we study sound propagation in stationary and locally irrotational vortex flows where the circulation is wound around a long (rotating) cylinder. Apart from the usual scattering solutions, we find…

When a drop falls from a moderate height into a shallow fluid pool whose depth is of the order of the drop-radius two pairs of vortex rings are generated. The inner pair forms at the edge of the crater created by the impacting drop while…

The low temperature dynamics of a vortex in a trapped quasi-two-dimensional Bose-Einstein condensate are studied quantitatively. Precession of an off-centred vortex in a dimple trap, embedded in a weaker harmonic trap, leads to the emission…