Quantum mechanics

Turbulence

Scale (ratio)

Vortex stretching

Turbulence kinetic energy

Vortex

Kinetic energy

Classical mechanics

Statistical physics

Dissipation

Strain (injury)

Thermodynamics

Energy transfer

Physics

Nonlinear system

Molecular physics

Vorticity

Phenomenological model

Internal medicine

Condensed matter physics

Length scale

Medicine

Mechanics

Strain rate

Physical Review Letters

An intrinsic feature of turbulent flows is an enhanced rate of mixing and kinetic energy dissipation due to the rapid generation of small-scale motions from large-scale excitation. The transfer of kinetic energy from large to small scales is commonly attributed to the stretching of vorticity by the strain-rate, but strain self-amplification also plays a role. Previous treatments of this connection are phenomenological or inexact, or cannot distinguish the contribution of vorticity stretching from that of strain self-amplification. In this paper, an exact relationship is derived which quantitatively establishes how intuitive multi-scale mechanisms such as vorticity stretching and strain self-amplification together actuate the inter-scale transfer of energy in turbulence. Numerical evidence validates this result and uses it to demonstrate that the contribution of strain self-amplification to energy transfer is higher than that of vorticity stretching, but not overwhelmingly so.

Energy Transfer from Large to Small Scales in Turbulence by Multiscale Nonlinear Strain and Vorticity Interactions