arXiv subjects

Thierry Dombre

Publications and source records attributed to Thierry Dombre.

3 recordsLinked to original sources

arXiv2010

Bose-like condensation of Lagrangian particles and higher-order statistics in passive scalar turbulent advection

We establish an hitherto hidden connection between zero modes and instantons in the context of the Kraichanan model for passive scalar turbulent advection, that relies on the hypothesis that the production of strong gradients of the scalar is associated with Bose-like condensation of Lagrangian particles. It opens the way to the computation of scaling exponents of the N-th order structure functions of the scalar by techniques borrowed from many-body theory. To lowest order of approximation, scaling exponents are found to increase asymptotically as log N in two dimensions.

physics.flu-dyn↗

arXiv1995

Intermittency, chaos and singular fluctuations in the mixed Obukhov-Novikov shell model of turbulence

The multiscaling properties of the mixed Obukhov-Novikov shell model of turbulence are investigated numerically and compared with those of the complex GOY model, mostly studied in the recent years. Two types of generic singular fluctuations are identified~: first, self-similar solutions propagating from large to small scales and building up intermittency, second, complex time singularities inhibiting the cascade and promoting chaos. A simple and robust method is proposed to track these objects. It is shown that the scaling exponent of self-similar solutions selected by the dynamics is compatible with large order statistics whenever it departs enough from the Kolmogorov value. Complex time singularities on the other hand get trapped on the last shells, when the proportion of Novikov interactions exceeds a critical value which is argued to mark the boundary between chaotic and regular dynamics in the limit of infinite Reynolds number.

chao-dyn↗

arXiv1995

The motion of holes on the triangular lattice: t-J model

The motion of holes on the triangular lattice is studied using the t-J model. Within the Born self-consistent approximation and the exact Lanczos diagonalization, the single hole physics is first analyzed. Then the spiral theory of Shraiman and Siggia is used to investigate the case of a finite density of holes.

cond-mat↗