Energy and vorticity dynamics in decaying isotropic turbulence

The mechanics of energy and vorticity decay associated with an exact solution to the von Karman-Howarth equation is described. Three distinct modes of decay are found to occur depending on the magnitude of the product of turbulent Reynolds number and skewness factor. Vortex stretching is shown to be responsible for transferring energy to wave numbers in the dissipation range. Vorticity accumulated in this process is dissipated by viscosity once the turbulence scale is reduced sufficiently by vortex stretching. Several comparisons to experimental data of the computed values of energy and microscale are given, with generally favorable result.