Cavitation pressure in liquid helium

We report observation of an inverse energy cascade in second sound acoustic turbulence in He II. Its onset occurs above a critical driving energy and it is accompanied by giant waves that constitute an acoustic analogue of the rogue waves that occasionally appear on the surface of the ocean. The theory of the phenomenon is developed and shown to be in good agreement with the experiments.

Traditionally, the occurrence of cavitation has been related to the ratio between flow velocity and pressure gradient in the case of hydrodynamic cavitation, or some combination of vapor pressure and surface tension. However, both formulations present a large discrepancy with experimental data for cases in which cavitation is induced by acoustic waves. The present study aims to identify a more suitable cavitation threshold for such cases. The methodology adopted in this work ...

This letter is based on the hypothesis of a small entropy content of the superfluid fraction of liquid helium. We show that such a superfluid entropy gives rise to a new sound mode in a ring-shaped superleak. This mode is named sixth sound. We propose an experiment by which its sound velocity and thereby the superfluid entropy can be measured. A negative experiment would yield a new upper limit for the superfluid entropy.

Using a nonlinear sound wave equation for a bubbly liquid in conjunction with an equation for bubble pulsation, we predict and experimentally demonstrate the appearance of a gap in the frequency spectrum of a sound wave propagating in a cavitation cloud comprising bubbles. For bubbles with an ambient radius of 100 {\mu}m, the calculations revealed that this gap corresponds to the phenomenon of sound wave localization. For bubbles with an ambient radius of 120 {\mu}m, this spe...

The effect of pressure and negative pressure on the modes of oscillation of a multi-electron bubble in liquid helium is calculated. Already at low pressures of the order of 10-100 mbar, these effects are found to significantly modify the frequencies of oscillation of the bubble. Stabilization of the bubble is shown to occur in the presence of a small negative pressure, which expands the bubble radius. Above a threshold negative pressure, the bubble is unstable.

The zero sound attenuation of normal liquid 3He has been studied over a range of temperatures from slightly above the superfluid transition temperature, Tc, to approximately 10 mK at the constant pressures of 1 bar and 5 bar. Using longitudinal LiNbO3 transducers, operating both on and off resonance, the experiment was performed at 15 discrete frequencies located in several broadband frequency windows, including 16 - 25 MHz, 60 - 70 MHz, and 105 - 111 MHz. The results are com...

To understand ultrasonic cavitation, it is imperative to analyze the effects of the gas-liquid phase transitions on soundwave propagation. Since current methods based on fluid dynamics offer limited information, it is imperative to carry out further research on this phenomenon. In this study, we investigated the effects of cavitation and near-critical fluid on soundwaves using the molecular dynamics (MD) simulations of Lennard-Jones fluids. In the first-order liquid-to-gas tr...

This study investigates the emission of light and sound from cavitation caused by intense pressure pulses in water. Based on time-resolved measurements of (a) pressure waveform at the focus, (b) light scattering upon cavitation, (c) acoustic emission, and (d) photoemission (sonoluminescence) it is shown that emissions occur upon the creation or expansion as well as the collapse of the cavity. These results suggest that the thermodynamic irreversibility, resulting from non-equ...

We have made precision measurements of the frequency of a collective mode of the superfluid 3He-B order parameter, the J=2- imaginary squashing mode. Measurements were performed at multiple pressures using interference of transverse sound in an acoustic cavity. Transverse waves propagate in the vicinity of this order parameter mode owing to off-resonant coupling. At the crossing of the sound mode and the order parameter mode, the sound wave is strongly attenuated. We use both...

Three-dimensional direct numerical simulations (DNS) are used to revisit the experiments on multibubble cavitation performed by Bremond et al. (https://doi.org/10.1063/1.2396922, Phys. Fluids 18, 121505 (2006), https://doi.org/10.1103/PhysRevLett.96.224501, Phys. Rev. Lett. 96, 224501 (2006)). In particular, we aim at understanding the asymmetry observed therein during the expansion and collapse of bubble clusters subjected to a pressure pulse. Our numerical simulations sugge...