Physical-Space Nonlocality in Decaying Isotropic Turbulence

Abstract

A systematic method of estimating the degree of nonlocal dependence of the rate-of-strain tensor upon the vorticity is proposed and applied to a numerical simulation of decaying isotropic turbulence. Locality functions defined with a screened strain show similarity after vortex tubes are formed if the screening radius is normalized by the Taylor microscale λ. About 40% (50%) of energy dissipation (enstrophy production) comes from such regions where the distance from the point of source vorticity is larger than 2λ. A physical interpretation of this finding is made in connection with Tennekes’ model [Phys. Fluids 11 (1968) 669].