Histograms of helicity and strain in numerical turbulence

Abstract

Histograms of the normalized values of the helicity and the smallest principal component of the rate of strain are found for one realization of a ${128}^3$ isotropic simulation of forced turbulence. In regions of high dissipation the strain has a structure indicating sheets. Peak-to-valley ratios in the helicity histograms are less than in other numerical flows and this ratio decreases further when the helical large scales are filtered or active regions characterized by the strain are sampled.