@Article{CiCP-18-4,
author = {},
title = {Dynamics and Instability of a Vortex Ring Impinging on a Wall},
journal = {Communications in Computational Physics},
year = {2015},
volume = {18},
number = {4},
pages = {1122--1146},
abstract = {<p style="text-align: justify;">Dynamics and instability of a vortex ring impinging on a wall were investigated
by means of large eddy simulation for two vortex core thicknesses corresponding
to thin and thick vortex rings. Various fundamental mechanisms dictating the
flow behaviors, such as evolution of vortical structures, formation of vortices wrapping
around vortex rings, instability and breakdown of vortex rings, and transition
from laminar to turbulent state, have been studied systematically. The evolution of
vortical structures is elucidated and the formation of the loop-like and hair-pin vortices
wrapping around the vortex rings (called briefly wrapping vortices) is clarified.
Analysis of the enstrophy of wrapping vortices and turbulent kinetic energy (TKE) in
flow field indicates that the formation and evolution of wrapping vortices are closely
associated with the flow transition to turbulent state. It is found that the temporal development
of wrapping vortices and the growth rate of axial flow generated around
the circumference of the core region for the thin ring are faster than those for the thick
ring. The azimuthal instabilities of primary and secondary vortex rings are analyzed
and the development of modal energies is investigated to reveal the flow transition
to turbulent state. The modal energy decay follows a characteristic −5/3 power law,
indicating that the vortical flow has become turbulence. Moreover, it is identified that
the TKE with a major contribution of the azimuthal component is mainly distributed
in the core region of vortex rings. The results obtained in this study provide physical
insight of the mechanisms relevant to the vortical flow evolution from laminar to
turbulent state.</p>},
issn = {1991-7120},
doi = {https://doi.org/10.4208/cicp.150115.210715s},
url = {https://global-sci.com/article/80356/dynamics-and-instability-of-a-vortex-ring-impinging-on-a-wall}
}