Lagrangian chaos and the effect of drag on the enstrophy cascade in two-dimensional turbulence
We investigate the effect of drag force on the enstrophy cascade of two-dimensional Navier-Stokes turbulence. We find a power law decrease of the energy wave number (k) spectrum that is faster than the classical (no-drag) prediction of k(-3). It is shown that the enstrophy cascade with drag can be analyzed by making use of a previous theory for finite lifetime passive scalars advected by a Lagrangian chaotic fluid flow. Using this we relate the power law exponent of the energy wave number spectrum to the distribution of finite time Lyapunov exponents and the drag coefficient.
Nam
K
Institute for Plasma Research, University of Maryland, College Park, Maryland 20742, USA.
Ott
E
Antonsen
TM
Guzdar
PN