The coherent structure of the kinetic energy transfer in shear turbulence

Abstract

The cascade of energy in turbulent flows, i.e., the transfer of kinetic energy from large to small flow scales or vice versa (backward cascade), is the cornerstone of most theories and models of turbulence since the 1940s. Yet, understanding the spatial organisation of kinetic energy transfer remains an outstanding challenge in fluid mechanics. Here, we unveil the three-dimensional structure of the energy cascade across the shear-dominated scales using numerical data of homogeneous shear turbulence. We show that the characteristic flow structure associated with the energy transfer is a vortex shaped as an inverted hairpin followed by an upright hairpin. The asymmetry between the forward and backward cascade arises from the opposite flow circulation within the hairpins, which triggers reversed patterns in the flow.

improved wording, fixed figure labels, some rephrasing

References in corpus (4)

• The turbulent cascade in five dimensions
• Destabilizing turbulence in pipe flow
• Causality of energy-containing eddies in wall turbulence
• Multiscale analysis of the topological invariants in the logarithmic region of turbulent channels at $R{e}_{\tau }=932$

Cited by in corpus (5)

• On the role of vorticity stretching and strain self-amplification in the turbulence energy cascade
• Anomalous Features in Internal Cylinder Flow Instabilities subject to Uncertain Rotational Effects
• Normality-based analysis of multiscale velocity gradients and energy transfer in direct and large-eddy simulations of isotropic turbulence
• Cascades and Kolmogorov's lognormal scaling in two-dimensional bacterial turbulence
• The contribution of dilatational motion to energy flux in homogeneous compressible turbulence