Turbulent viscosity and Lambda-effect from numerical turbulence models

TL;DR

This paper uses simplified turbulence simulations to analyze off-diagonal Reynolds stress components, focusing on turbulent viscosity and Lambda-effect, with implications for understanding anisotropic turbulence.

Contribution

It introduces a simplified model for turbulence to study Reynolds stresses, avoiding complexities of stratified convection and revealing clearer insights.

Findings

Off-diagonal Reynolds stress components are characterized.

Turbulent viscosity and Lambda-effect are parameterized.

Simpler system avoids puzzling features seen in convection studies.

Abstract

Homogeneous anisotropic turbulence simulations are used to determine off-diagonal components of the Reynolds stress tensor and its parameterization in terms of turbulent viscosity and Lambda-effect. The turbulence is forced in an anisotropic fashion by enhancing the strength of the forcing in the vertical direction. The Coriolis force is included with a rotation axis inclined relative to the vertical direction. The system studied here is significantly simpler than that of turbulent stratified convection which has often been used to study Reynolds stresses. Certain puzzling features of the results for convection, such as sign changes or highly concentrated latitude distributions, are not present in the simpler system considered here.