Superfluid (quantum) turbulence and distributed chaos

TL;DR

This paper investigates the properties of distributed chaos in superfluid turbulence using numerical simulations, revealing different spectral behaviors for normal and superfluid components and their relation to large-scale structures.

Contribution

It provides new insights into the spectral characteristics of superfluid turbulence and the role of vorticity and homogeneity breaking in distributed chaos.

Findings

Normal component exhibits a stretched exponential spectrum with β=2/3.

Superfluid component's chaos is dominated by vorticity correlation with β=1/2.

At very low temperatures, chaos is tuned to large-scale coherent motions.

Abstract

Properties of distributed chaos in superfluid (quantum) turbulence have been studied using the data of recent direct numerical simulations (HVBK two-fluid model for He II, and a moving grid in the frames of Gross-Pitaevskii model of the Bose-Einstein condensates at low temperatures). It is found that for the viscous (normal) component of the velocity field in He II the viscosity dominates the distributed chaos with the stretched exponential spectrum $\exp(-k/k_{\beta})^{\beta}$ and $\beta = 2/3$. For the superfluid component the distributed chaos is dominated by the vorticity correlation integral with $\beta =1/2$ (the soft spontaneous breaking of the space translational symmetry - homogeneity). For very low temperature the distributed chaos is tuned to the large-scale coherent motions: the viscous (normal) component is tuned to the fundamental mode, whereas the superfluid component is subharmonically tuned. For the Gross-Pitaevskii superfluid turbulence incompressible part of the energy spectrum (containing the vortices contribution) also indicates the distributed chaos dominated by the vorticity correlation integral ($\beta =1/2$) and the subharmonic tuning to the large-scale coherent motions.