Kinetic energy transfer between internal gravity waves and turbulence

Abstract

We describe a reliable method for distinguishing the mean, wave and turbulence fields when internal waves with changing amplitude perturb the turbulent boundary layer. By integrating the component wave and turbulence kinetic energy budgets through the turbulent layer, we show that the only mechanism transferring energy between wave and turbulent fields is the work done by the periodic part of the turbulent stress against the wave rate of strain. When these components are π/2 out of phase, the net energy transfer is zero. Eight wave-turbulence interaction events of differing stability are analyzed and interpreted using rapid distortion theory. When density stratification is approximately steady, the phase relationship does not change from π/2. However, periodicity in the stratification changes the phase angle and leads to strong energy transfer from wave to turbulence. -Author