Abstract

Abstract

Highlights

  • According to the Kolmogorov’s theory, the prominent feature of high-Reynolds-number turbulent flows is the energy transfer from large to small scales believed to universally occur in the inertial subrange

  • The formalism is based on the second-order moment of the two-point velocity increment

  • A further step towards the study of the essential features of free-shear flows is to consider the evolution of plane turbulent jets in time rather than in space. This choice allows us to recover a statistical homogeneity in space while loosing that in time. This simple exchange of statistical symmetries allows for a simpler formulation of the problem since the statistical formalisms representing the inhomogeneity in time are represented by single processes, e.g. momentum and energy flux in time, and, are far less complex than the formalisms representing inhomogeneity in space which involve multiple physical processes, e.g. momentum flux in space, viscous, turbulent and pressure energy fluxes in space and turbulence production due to mean velocity gradient in space

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Summary

Introduction

According to the Kolmogorov’s theory, the prominent feature of high-Reynolds-number turbulent flows is the energy transfer from large to small scales believed to universally occur in the inertial subrange. Kolmogorov’s groundbreaking intuition was reducing the complex problem of turbulence to its essential features, by assuming homogeneity and isotropy In these conditions, the main process is the transfer of energy among scales which is described by a single scalar quantity, the average dissipation rate. This simple exchange of statistical symmetries allows for a simpler formulation of the problem since the statistical formalisms representing the inhomogeneity in time are represented by single processes, e.g. momentum and energy flux in time, and, are far less complex than the formalisms representing inhomogeneity in space which involve multiple physical processes, e.g. momentum flux in space, viscous, turbulent and pressure energy fluxes in space and turbulence production due to mean velocity gradient in space For these reasons, direct numerical simulations of temporal jets represent a very useful tool for the analysis of the essential features of free-shear flows

Theoretical framework
Inhomogeneity and flow regions
Scale-energy paths
Family of fluxes B
Family of fluxes C
Scale-by-scale budgets
Production region I
Inner region II
External region IV
Findings
Conclusions
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