On filtering in the viscous-convective subrange for turbulent mixing of high Schmidt number passive scalars

On filtering in the viscous-convective subrange for turbulent mixing of high Schmidt number passive scalars

The viscous-convective subrange in nonstationary turbulence

The similarity form of the scalar-variance spectrum at high Schmidt numbers is investigated for nonstationary turbulence. Theoretical arguments show that Batchelor scaling may apply only at high Reynolds numbers. At low Reynolds numbers, Batchlor scaling is not possible unless the turbulence is stationary or the enstrophy decays asymptotically as t. When this latter condition is satisfied, it i...

The Fokker–Planck closure for turbulent molecular mixing: Passive scalars

Lagrangian views on turbulent mixing of passive scalars.

The Lagrangian view of passive scalar turbulence has recently produced interesting results and interpretations. Innovations in theory, experiments, simulations and data analysis of Lagrangian turbulence are reviewed here in brief. Part of the review is closely related to the so-called Kraichnan model for the advection of the passive scalar in synthetic turbulence. Possible implications for a be...

Geometric features of the mixing of passive scalars at high Schmidt numbers.

The mixing of passive scalars of decreasing diffusivity, advected in each case by the same three-dimensional Navier-Stokes turbulence, is studied. The mixing becomes more isotropic with decreasing diffusivity. The local flow in the vicinity of steepest negative and positive scalar gradients is in general different, and its behavior is studied for various values of the scalar diffusivity. Mixing...