Speaker
Alessandra S. Lanotte
(LE)
Description
The dynamical effects of mode reduction in Fourier space for three dimensional turbulent flows is
studied. We present fully resolved numerical simulations of the Navier-Stokes equations with Fourier modes constrained to live on a fractal set of dimension D. The robustness of the energy cascade and
vortex stretching mechanisms are tested at changing D, from the standard three dimensional case
to a strongly decimated case for D = 2:5, where only about 3% of the Fourier modes interact. While
the direct energy cascade persist, deviations from the classical Kolmogorov scaling are observed in the kinetic
energy spectra. A model in terms of a correction with a linear dependency on the co-dimension of the fractal set explains the results. At small scales, the intermittent behaviour
due to the vorticity production is strongly modified by the fractal decimation, leading to an almost
Gaussian statistics already at D ~ 2.98. These effects are connected to a genuine modification in
the triad-to-triad nonlinear energy transfer mechanism.
Primary author
Co-authors
Prof.
Federico Toschi
(TUE Eindhoven)
Luca Biferale
(ROMA2)
Roberto Benzi
(ROMA2)
Dr
Shiva Kumar Malapaka
(IIIT India)
