Passive Scalar Structures in Supersonic Turbulence

TL;DR

This study investigates passive scalar structures in supersonic turbulence, revealing that scalar intermittency increases slightly with Mach number, and scalar structures remain sheet-like, differing from velocity structures which become more intermittent.

Contribution

It provides a systematic numerical analysis of passive scalar intermittency and structure morphology across different Mach numbers in supersonic turbulence.

Findings

Scalar intermittency increases slightly with Mach number

Scalar structures are predominantly sheet-like at all Mach numbers

Scalar structure functions align with She and Lévéque's intermittency model

Abstract

We conduct a systematic numerical study of passive scalar structures in supersonic turbulent flows. We find that the degree of intermittency in the scalar structures increases only slightly as the flow changes from transonic to highly supersonic, while the velocity structures become significantly more intermittent. This difference is due to the absence of shock-like discontinuities in the scalar field. The structure functions of the scalar field are well described by the intermittency model of She and L\'{e}v\^{e}que [Phys. Rev. Lett. 72, 336 (1994)], and the most intense scalar structures are found to be sheet-like at all Mach numbers.