Lagrangian time correlations of vorticity alignments in isotropic turbulence: observations and model predictions

Abstract

Motivated by results from recent particle tracking experiments in turbulence (Xu et al., Nat. Phys. 7, 709 (2011)), we study the Lagrangian time correlations of vorticity alignments with the three eigenvectors of the deformation-rate tensor. We use data from direct numerical simulations (DNS), and explore the predictions of a Lagrangian model for the velocity gradient tensor. We find that the initial increase of correlation of vorticity direction with the most extensive eigen-direction observed by Xu et al. is reproduced accurately using the Lagrangian model, as well as the evolution of correlation with the other two eigendirections. Conversely, time correlations of vorticity direction with the eigen-frame of the pressure Hessian tensor show differences with the model.

4 pages, 2 figures, minor changes, final version published in Phys. Fluids

References in corpus (3)

• Lagrangian dynamics and statistical geometric structure of turbulence
• Modeling the pressure Hessian and viscous Laplacian in Turbulence: comparisons with DNS and implications on velocity gradient dynamics
• Viscous tilting and production of vorticity in homogeneous turbulence

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• Instantons in a Lagrangian model of turbulence
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• Lagrangian view of time irreversibility of fluid turbulence