lmd_LEGACY1987_abstracts.html

1987 .

A. Babiano, C. Basdevant, B. Legras, and R. Sadourny. Vorticity and passive-scalar dynamics in two-dimensional turbulence. Journal of Fluid Mechanics, 183:379-397, October 1987. [ bib | DOI | ADS link ]

The simple similarity theory a la Kolmogorov (SK theory) does not distinguish between vorticity and passive-scalar dynamics. In this paper, the vorticity and passive scalar dynamics in two-dimensional turbulence were studied in parallel, using semidirect numerical simulations. It is shown that a passive scalar forced and dissipated under the same conditions as vorticity, has a quite different behavior. The passive scalar obeys the SK theory, while the vorticity has the capacity to organize itself into sporadic, strong coherent vortices; the condensation of vorticity into such vortices depends critically both on the existence of an energy invariant (intimately related to the feedback of vorticity transport on velocity) and on the localness of flow dynamics in physical space.