A Study of the Development and Topology of a Vortex with Inflow in Isotropic Homogeneous Turbulence

Abstract

This paper investigates local flow geometry characteristics of inflow vortices in isotropic homogenous turbulence. Eigenvalues and eigenvectors of the velocity gradient tensor are applied to specify the Galilei invariant local flow geometry, and the real part of complex eigenvalues is used to classify the vortex as inflow or outflow. However, the real part can classify only average inflow or outflow, whereas another property, which we term “sourcity,” specifies uniformity of the radial flow direction. We analyze the characteristics of inflow vortices using sourcity with inflow from all or partial directions.
The analysis shows that the rate of vortices with inflow from all directions is approximately 16% of all (average) inflow vortices, and that most inflow vortices include partial outflow. A vortex with inflow from all directions has greater symmetry. Although sourcity mathematically decreases for high-intensity swirling, it increases if swirling develops with vortical flow symmetry, especially for weak vortices.