The turbulence velocity gradient tensor formed additively by normal and non-normal tensors

Abstract

We decompose the velocity gradient tensor for turbulence into normal and non-normal parts, and condition our analysis on the strain eigenvector alignments between these tensors. We identify states that always enhance, and always counteract the axisymmetric expansion state, and give a rationale for decomposing the production balance term into its constituents: complex behavior arises when the dominant strain alignments involve the non-normal tensor. Finally, we develop a topological analysis framework where mathematical bounds on two of the three variables leads to an analysis in two planes.

arXiv comment11 pages, 3 figures

References in corpus (9)

• Improved surrogate data for nonlinearity tests
• A public turbulence database cluster and applications to study Lagrangian evolution of velocity increments in turbulence
• Discrimination power of measures for nonlinearity in a time series
• Spectral Dynamics of the Velocity Gradient Field in Restricted Flows
• Pressure Hessian and viscous contributions to velocity gradient statistics based on Gaussian random fields
• Influence of the spatial resolution on fine-scale features in DNS of turbulence generated by a single square grid
• A closure for Lagrangian velocity gradient evolution in turbulence using recent deformation mapping of initially Gaussian fields
• Multi-scale model of gradient evolution in turbulent flows
• A multifractal surrogate data generation algorithm that preserves pointwise Holder regularity structure, with initial applications to turbulence