title: Influence of compressibility on the Lagrangian statistics of vorticity-strain-rate interactions.
abstract: The objective of this study is to investigate the influence of compressibility on Lagrangian statistics of vorticity and strain-rate interactions. The Lagrangian statistics are extracted from "almost" time-continuous data sets of direct numerical simulations of compressible decaying isotropic turbulence by employing a cubic spline-based Lagrangian particle tracker. We study the influence of compressibility on Lagrangian statistics of alignment in terms of compressibility parameters-turbulent Mach number, normalized dilatation-rate, and flow topology. In comparison to incompressible turbulence, we observe that the presence of compressibility in a flow field weakens the alignment tendency of vorticity toward the largest strain-rate eigenvector. Based on the Lagrangian statistics of alignment conditioned on dilatation and topology, we find that the weakened tendency of alignment observed in compressible turbulence is because of a special group of fluid particles that have an initially negligible dilatation-rate and are associated with stable-focus-stretching topology.
authors: Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi 110016, India.
authors: Mohammad
authors: M
authors: Danish
authors: Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi 110016, India.
authors: Sawan Suman
authors: SS
authors: Sinha
authors: Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi 110016, India.
authors: Balaji
authors: B
authors: Srinivasan