Intermittency in the isotropic component of helical and non-helical turbulent flows

TL;DR

This study investigates the intermittency and scaling laws of the isotropic component in turbulent flows with different forcings and Reynolds numbers, revealing increased intermittency with Reynolds number and minimal impact of helicity.

Contribution

The paper applies SO(3) decomposition to high-resolution DNS data to analyze scaling laws and intermittency in helical and non-helical turbulent flows across a broad Reynolds number range.

Findings

Intermittency increases with Reynolds number.

Helicity has negligible effect on scaling exponents.

SO(3) decomposition improves convergence of scaling exponents.

Abstract

We analyze the isotropic component of turbulent flows spanning a broad range of Reynolds numbers. The aim is to identify scaling laws and their Reynolds number dependence in flows under different mechanical forcings. To this end, we applied an SO(3) decomposition to data stemming from direct numerical simulations with spatial resolutions ranging from 64^3 to 1024^3 grid points, and studied the scaling of high order moments of the velocity field. The study was carried out for two different flows obtained forcing the system with a Taylor-Green vortex or the Arn'old-Beltrami-Childress flow. Our results indicate that helicity has no significant impact on the scaling exponents. Intermittency effects increase with the Reynolds number in the range of parameters studied, and are larger than what can be expected from several models in the literature. Finally, we confirm previous results showing the use of the SO(3) decomposition improves the convergence of scaling exponents.