Numerical search for states with constant enstrophy flux over finite time intervals in two-dimensional turbulence

TL;DR

This paper numerically investigates whether states with constant enstrophy flux in 2D turbulence resemble turbulence states, supporting a proposed ensemble model by comparing properties with direct numerical simulations.

Contribution

It provides a numerical validation of the conjecture that states with constant flux are representative of turbulence states in 2D turbulence.

Findings

States with constant enstrophy flux exhibit energy spectra similar to turbulence.

The properties depend on the time interval and initial conditions.

Comparison with DNS shows qualitative agreement.

Abstract

An ensemble model of turbulence based on states with constant flux in wavenumber space was proposed in [K. Yoshida, Phys. Rev. E, 106, 045106 (2022)]. The justification of this ensemble model relies on the conjecture that almost all states with constant flux correspond to turbulence states. To verify this conjecture, a numerical search for states with constant enstrophy flux in wavenumber space over finite time intervals in two-dimension turbulence is conducted using a Monte Carlo method. Properties of the obtained states, such as energy spectrum and spectra related to fourth-order moments, are examined and compared with those of turbulence states obtained from direct numerical simulations. The dependence of the obtained states on the time interval and the initial conditions used in the numerical search is also discussed.