Self-truncation and scaling in Euler-Voigt-α and related fluid models.
A generalization of the 3D Euler-Voigt-α model is obtained by introducing derivatives of arbitrary order β (instead of 2) in the Helmholtz operator. The β→∞ limit is shown to correspond to Galerkin truncation of the Euler equation. Direct numerical simulations (DNS) of the model are performed with resolutions up to 2048(3) and Taylor-Green initial data. DNS performed at large β demonstrate that this simple classical hydrodynamical model presents a self-truncation behavior, similar to that previously observed for the Gross-Pitaeveskii equation in Krstulovic and Brachet [Phys. Rev. Lett. 106, 115303 (2011)]. The self-truncation regime of the generalized model is shown to reproduce the behavior of the truncated Euler equation demonstrated in Cichowlas et al. [Phys. Rev. Lett. 95, 264502 (2005)]. The long-time growth of the self-truncation wave number k(st) appears to be self-similar. Two related α-Voigt versions of the eddy-damped quasinormal Markovian model and the Leith model are introduced. These simplified theoretical models are shown to reasonably reproduce intermediate time DNS results. The values of the self-similar exponents of these models are found analytically.
LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universits, UPMC University Paris 6, UMR 8112, F-75014, Paris, France.
Giuseppe
G
Di Molfetta
Laboratoire Lagrange, UMR7293, Université de Nice Sophia-Antipolis, CNRS, Observatoire de la Côte dAzur, BP 4229, 06304 Nice Cedex 4, France.
Giorgio
G
Krstlulovic
Laboratoire de Physique Statistique de l'Ecole Normale Supérieure/PSL Research University, associé au CNRS et aux Universités Pierre-et-Marie-Curie Paris 06 et Paris Diderot, 24 Rue Lhomond, 75231 Paris, France.
Marc
M
Brachet