Effects of helicity on Lagrangian and Eulerian time correlations in turbulence

Abstract

Taylor series expansions of turbulent time correlation functions are applied to show that although to second order, helicity does not affect Lagrangian time correlations, the corresponding helicity effect on Eulerian time correlations is nonzero. This result is applied to two problems in which Eulerian time correlations are relevant: sound radiation and scattering by turbulence. Helicity shifts radiated sound to lower frequencies and increases the angle between scattered and incident sound waves. © 1999 American Institute of Physics.