Intermittency and universality in a Lagrangian model of velocity gradients in three-dimensional turbulence

The universality of intermittency in hydrodynamic turbulence is considered based on a recent model for the velocity gradient tensor evolution. Three possible versions of the model are investigated differing in the assumed correlation time-scale and forcing strength. Numerical tests show that the same (universal) anomalous relative scaling exponents are obtained for the three model variants. It is also found that transverse velocity gradients are more intermittent than longitudinal ones, whereas dissipation and enstrophy scale with the same exponents. The results are consistent with the universality of intermittency and relative scaling exponents, and suggest that these are dictated by the self-stretching terms that are the same in each variant of the model.