Turbulent dissipative coupling in nanoscale multimode superfluid acoustics

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Hauptverfasser: Novotný, Filip, Talíř, Marek, Varga, Emil
Format: Preprint
Veröffentlicht: 2024
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author Novotný, Filip
Talíř, Marek
Varga, Emil
author_facet Novotný, Filip
Talíř, Marek
Varga, Emil
contents Superfluid helium, the inviscid low-temperature phase of liquid \4He, enables investigation of flows with reduced dimensionality since, due to the vanishing viscosity, sub-micron flow channels can be constructed. In such strongly confined volumes filled with superfluid, the longitudinal acoustic wave is a coupled fluctuation of pressure and entropy density called fourth sound. In this work, we use multiple 4th sound acoustic modes inside a nano-superfluidic acoustic resonator in a pump-probe arrangement to observe localized clusters of quantized vortices leading to two-dimensional turbulence. The localised turbulence enables controllable and asymmetric dissipative coupling between acoustic modes. Furthermore, we derive a general procedure for analytically estimating the superfluid acoustic resonance frequencies inside a volume with mechanically compliant walls. Our work confirms earlier assumptions that turbulence in similar nanofluidic systems initially develops in localized areas of high shear. The multimode pump-probe methods presented here will allow future experiments to study the dynamics of two-dimensional quantum turbulence, e.g., the free decay.
format Preprint
id arxiv_https___arxiv_org_abs_2412_15110
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Turbulent dissipative coupling in nanoscale multimode superfluid acoustics
Novotný, Filip
Talíř, Marek
Varga, Emil
Fluid Dynamics
Mesoscale and Nanoscale Physics
Superfluid helium, the inviscid low-temperature phase of liquid \4He, enables investigation of flows with reduced dimensionality since, due to the vanishing viscosity, sub-micron flow channels can be constructed. In such strongly confined volumes filled with superfluid, the longitudinal acoustic wave is a coupled fluctuation of pressure and entropy density called fourth sound. In this work, we use multiple 4th sound acoustic modes inside a nano-superfluidic acoustic resonator in a pump-probe arrangement to observe localized clusters of quantized vortices leading to two-dimensional turbulence. The localised turbulence enables controllable and asymmetric dissipative coupling between acoustic modes. Furthermore, we derive a general procedure for analytically estimating the superfluid acoustic resonance frequencies inside a volume with mechanically compliant walls. Our work confirms earlier assumptions that turbulence in similar nanofluidic systems initially develops in localized areas of high shear. The multimode pump-probe methods presented here will allow future experiments to study the dynamics of two-dimensional quantum turbulence, e.g., the free decay.
title Turbulent dissipative coupling in nanoscale multimode superfluid acoustics
topic Fluid Dynamics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2412.15110