Excitations of vortex waves in weakly compressible isotropic turbulence

Abstract

Compressibility effects on vortices in weakly compressible isotropic turbulence are investigated numerically. Comparison of vortices in compressible and incompressible turbulence reveals that the vortex stretching is weakened by compressibility. The suppression leads to slow growth of vortices and brings about thin and less-swirling vortices. It is also found that vortex waves whose wavelengths are as long as vortex diameters are excited along compressible vortex axes. It is shown that the wavelength does not depend on the strength of compressibility and that excitation of vortex waves at this wavelength is intrinsic to compressible turbulence. Propagations of the pressure fluctuation in compressible turbulence are contributed as much by the vortex waves as by acoustic waves. These properties are useful to differentiate between vortices in compressible and incompressible turbulence.

This paper was chosen from Selected Proceedings of the Third International Symposium on Turbulence and Shear Flow Phenomena (Sendai, Japan, 24–27 June 2003).